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  1. #1
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    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks

    What happens to shimano brake pads when my bike sits in the basement for 6-8 weeks without riding? Help me, I'm baffled.

    Backstory:
    In the last 2 years, my wife have had over 7 bikes in our house each with either Shimano M98x or M78x brakes on them. They either came stock on a bike, or I bled them and installed them myself.

    We'll ride a bike for couple months in the fall, brakes work great-- quiet, powerful, zero drama. put the bike in the basement for a couple months, pull it out in March to ride, and boom-- brakes squeal like crazy, less grabby, less power. Bikes are stored right side up, in various parts of my basement, leaning against a wall, etc.

    This has been happening on various bikes. Various pad compounds, organic and metallic, finned and not finned. Genuine Shimano and truckerco pads.

    Removing and sanding sometimes helps, but often only for a minute or two-- full power just doesn't return.

    My solution is to buy cheap (truckerco) pads in bulk and replace when this happens.

    My LBS has said the same thing about their XT equipped demo/rental bikes that sit for a month plus without use. What gives?

    What the heck am I missing? Please share your well thought out hypothesis.

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    I just can't buy into the notion that pads get contaminated by "absorbing moisture from the air while sitting idle" or some such thing.

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    Did you notice any oil residue or any other sign of leaks or pad contamination?

    One thing I can think of, at least on the M78x brakes is a slow leak on the o-ring between the two caliper halves on the banjo bolt. If the bike is ridden frequently it keeps the oil burned off so the pads don't get contaminated, but let the bike sit for long enough and the oil will get into the pads. This however doesn't explain the M98x since with one piece calipers it doesn't have that o-ring. The only other possibility is bad piston seals, but this isn't Avid here so it's very unlikely.

    One possible solution would be to remove the brake pads when you put the bikes into storage, then check the calipers at the beginning of the season and clean them if needed. As an experiment, you could try leaving the pads in on one bike and then compare it against the bikes where the pads were removed. If both sets are bad, it's a pad problem, if only the set that was left on went bad, it's a leaking caliper.

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    Re: XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks

    I just rode my bike with xt brakes for the first time in 2.5 months and the front brake has significantly less bite and requires more force than the rear. It also squeals sometimes. I suspect it's the phenomenon discussed above.

    What is the solution? New pads?

    Have others experienced this?

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    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks

    I'm having issues with my rear XT. Front works great but the back has much less power and squeals. It lever feels firm but just no stopping power so guessing the pad are dodgy.

    Also noticed last time I bled them when I removed the rear pads it looked a bit gunky and slimy around the calipers. I suspect that I have oil leaking out from the calipers or the seal between the two halves of the caliper.

    Going to take another look after upcoming race and might try getting them warrentied. Bought online though so not holing out much hope...

  7. #7
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    Bizarre but likely from minor leak in caliper.pull the pads next time but leave them in the same room to see what happens?
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    Yeah, sounds like a caliper leak and some bleeding necessary. Of course just bleeding is a very short term fix if you've in need of a caliper seal.

    Racing on compromised brakes huh? I would at the least do a bleed job before the race. This is one of the few situations where I would do a top down bleed given the origin of air would be at the caliper.
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    Quote Originally Posted by Cleared2land View Post
    Yeah, sounds like a caliper leak and some bleeding necessary. Of course just bleeding is a very short term fix if you've in need of a caliper seal.
    Why do you say bleeding is needed? It doesn't feel soft or spongy at all. It just has no bite. It feels like a coefficient of friction at the pads kind of thing.

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    Try scuffing the rotor up with some sand paper and clean them ... Then try them out... I kinda feel when they get contaminated there really is no great save... I just lost a pair of barely used icetech rotors due to sitting

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    Does it get pretty hot in your basement - boiler down there or something? I have the same when my bikes have been sitting in the shed in my garden for a few weeks during the summer heat. I'd assumed it was a bit of oil weeping past the piston seals due to the heat causing expansion. Seem to return to normal after the first few minutes of a ride, with the help of a bit of deliberately heavy braking to help burn off any contaminants.

    I read somewhere that Shimano brakes can only release pressure from the system by actuating the lever, otherwise they are a 'closed' system. So if they heat up in a car interior during the summer for example, expansion may cause oil to escape from the weakest part of the system - the piston seals.
    Last edited by PerthMTB; 04-07-2014 at 05:32 AM.

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    Quote Originally Posted by matto6 View Post
    Why do you say bleeding is needed? It doesn't feel soft or spongy at all. It just has no bite. It feels like a coefficient of friction at the pads kind of thing.

    Ok, I should have replied with a quote from skinnybeans (below). Obviously, I wasn't replying to Matto6 because Matto6 didn't say anything about the caliper looking "gunky and slimy" or "having oil leaking around caliper". If your caliper is leaking then you likely have introduced air and thus a bleed would be required.


    Quote Originally Posted by skinnybeans View Post
    I'm having issues with my rear XT. Front works great but the back has much less power and squeals. It lever feels firm but just no stopping power so guessing the pad are dodgy.

    Also noticed last time I bled them when I removed the rear pads it looked a bit gunky and slimy around the calipers. I suspect that I have oil leaking out from the calipers or the seal between the two halves of the caliper.

    Going to take another look after upcoming race and might try getting them warrentied. Bought online though so not holing out much hope...
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    I can't believe this thread is on here I came on to post about the same situation with my Shimano SLX brakes(latest generation). Rode my mtb for the 1st time since November. Bike was stored in a dry basement, upright. Brakes were fine when bike was last ridden. I took the bike for a road ride tonight and the brakes squealed like a pig. Back brake felt like it had no bite at all, front had some. levers felt normal. I took some automotive disc brake cleaner and wiped off the rotors and the rag really took off a lot of blackish grime? gunk?. This helped some but still not ideal at all. I will look at pads tomorrow.

    Could what ever brake dust and grime that was left on the pads and rotors, from the end of last season, have hardened into some sort of film or glaze that just needs to be burned off? Like they need to be bedded in again, like when the brakes are brand new?

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    Guys, guys..... This is simply your bike telling you "don't you ever go this long again without riding me".

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    Thought I'd pass this info onto you guys. Above I reported the same problem with my SLX brakes. I cleaned the rotors with automotive brake disc cleaning spray. A lot of grime(brake dust?) came off the rotors. I then pulled the brake pads and also cleaned them with the same cleaning spray. again a lot of black grime(brake dust/dirt?) came off the pads. I unbolted the calipers and inspected inside where the pistons are. I could see no traces of any fluid but there was lots of brake dust. I thoroughly cleaned the calipers too but with rubbing alcohol.

    I then went on my first trail ride of the season, about an hour ride. At first the brakes still felt the same- plenty of power and correct lever feel but no bite. About 1/2 into the ride all of a sudden the "bite" started returning, even to the point that I went into a skid a few times. By the end of the ride the brakes felt pretty much back to normal, more so in the front than in the rear. After my next trail ride I am hoping they'll feel 100% normal. I might bleed the back brake if it doesn't feel perfect.

    Not sure why we are experiencing this issue but thought I'd share my findings.

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    What pads are most of you on? Sintered or organic?

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    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks

    Quote Originally Posted by rfxc View Post
    What happens to shimano brake pads when my bike sits in the basement for 6-8 weeks without riding? Help me, I'm baffled.

    Backstory:
    In the last 2 years, my wife have had over 7 bikes in our house each with either Shimano M98x or M78x brakes on them. They either came stock on a bike, or I bled them and installed them myself.

    We'll ride a bike for couple months in the fall, brakes work great-- quiet, powerful, zero drama. put the bike in the basement for a couple months, pull it out in March to ride, and boom-- brakes squeal like crazy, less grabby, less power. Bikes are stored right side up, in various parts of my basement, leaning against a wall, etc.

    This has been happening on various bikes. Various pad compounds, organic and metallic, finned and not finned. Genuine Shimano and truckerco pads.

    Removing and sanding sometimes helps, but often only for a minute or two-- full power just doesn't return.

    My solution is to buy cheap (truckerco) pads in bulk and replace when this happens.

    My LBS has said the same thing about their XT equipped demo/rental bikes that sit for a month plus without use. What gives?

    What the heck am I missing? Please share your well thought out hypothesis.
    Dust. Just wipe the rotors with a clean damp cloth.
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  18. #18
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    Corrosion would be my guess, there's lots of metal in sintered pads. Leaks don't just happen overnight, it's likely the pads need a scuff and a re-bedding...
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  19. #19
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    I have this same issue. I got my bike with 2013 XT brakes (don't know the type, just that they're not with the ventilated, finned pads) in September last year and rarely rode it during the winter. When the bike was brand new, the brakes were grippy as hell, genuinely one-finger brakes as two would've been too much. No I have to squeeze with two fingers really hard (esp. the front brake) to get them to lock. Especially the front one is really noisy, too. The bike has 300km on it!
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  20. #20
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    Quote Originally Posted by Son View Post
    I have this same issue. I got my bike with 2013 XT brakes (don't know the type, just that they're not with the ventilated, finned pads) in September last year and rarely rode it during the winter. When the bike was brand new, the brakes were grippy as hell, genuinely one-finger brakes as two would've been too much. No I have to squeeze with two fingers really hard (esp. the front brake) to get them to lock. Especially the front one is really noisy, too. The bike has 300km on it!
    All of these experiences are news to me, but I suspect it could have something to do with dust accumulation. I live where I am able to ride with some regularity through most of the winter. So, I can add that I have never seen this issue. Assuming there are no leaks and the pads haven't become contaminated, what else could it be other than some dust accumulation? I really don't know. I have experienced a similar braking situation when riding through very powdery, talcum-like sand and noted reduced braking efficiency something like described on one occasion.

    Perhaps a good cleaning several times throughout the winter or during storage periods. I wouldn't squeeze the brakes until cleaned to possibly test the theory. I simply can't think of any other possibility that would contribute to this problem.
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    hi all,

    i was going to start a new thread, but thought i would pose a few questions on this one. i have saint br-M820 brakes (180mm front, 160mm rear) on my santa cruz nomad. they have been mostly fine since i got them. last week i took them to my LBS for a bleed, and when i got my bike back, the front brake had no power, and was squealing super loudly. i assumed that it would just require a bed-in, and the LBS said the same.

    well, i tried pedalling around quite a bit, and i wasn't able to bed them in. took the bike for a ~15 mile ride with about 2k feet of descent, and while a little bit more power, not much.

    a few questions:

    -i ride my bike 2-3x a week, and the winters here are mild enough in california that i ride year round, so i don't think it is the storage issue
    -the rear brake is perfectly fine: full power, full modulation, no noise
    -is it possible that the pads were contaminated w/ mineral oil or something else during the bleed procedure? i took it back to the shop and they sanded the pads and cleaned the disc again, but no change: very little power, lots of noise
    -does anyone know if the saint's come w/ metal or resin pads stock? none of the shimano technical documentation seems to help

    i wanted to ask before i order some new pads and swap them out--thanks in advance!
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    Quote Originally Posted by dth656 View Post
    last week i took them to my LBS for a bleed, and when i got my bike back, the front brake had no power, and was squealing super loudly. i assumed that it would just require a bed-in, and the LBS said the same.


    -is it possible that the pads were contaminated w/ mineral oil or something else during the bleed procedure? i took it back to the shop and they sanded the pads and cleaned the disc again, but no change: very little power, lots of noise
    -does anyone know if the saint's come w/ metal or resin pads stock? none of the shimano technical documentation seems to help

    i wanted to ask before i order some new pads and swap them out--thanks in advance!
    First, If you did NOT have new pads installed, then there is no reason to 'bed them in'. That's only a new brake pad requirement.

    Second, if the brakes were working fine before the LBS bleed them (other than the necessary bleed for which you took the bike in for), I would have to assume that they indeed were responsible for the issue. To further the inquiry... is your front brake lever soft or spongy or is the only apparent problem a lack of friction (pad to rotor) such as might be experienced with contaminated pads. My question is really trying to determine if the bleed job was not done correctly or inadequately, or do you think it's a contamination problem?

    Either way, I would place the problem back to the LBS. That is unless you had a contamination issue before you took the bike in for a bleed. It does sound like they are contaminated and just sanding will not correct the problem. If the LBS is responsible, they should either correct your problem or replace the pads.

    Regarding your brake pads, look on the back of them to determine what you have. If metal, I believe the part number will begin with a M. Such as M06. I think, but not sure that the resin or organics begin with an F.
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    thanks for the feedback cleared2land. both levers that were bled feel crisp, and not spongy at all, so everything good there. it's more the lack of power in braking, or as you said, it feels like the coefficient of kinetic friction between the pad and rotor is much less now, leading me to believe its pad contamination.

    i'll order new pads and a shimano bleed kit on monday (having watched quite a few videos on bleeding shimano brakes), so henceforth, i'm hoping to just service them myself.
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    Quote Originally Posted by Cleared2land View Post
    All of these experiences are news to me, but I suspect it could have something to do with dust accumulation. I live where I am able to ride with some regularity through most of the winter. So, I can add that I have never seen this issue. Assuming there are no leaks and the pads haven't become contaminated, what else could it be other than some dust accumulation? I really don't know. I have experienced a similar braking situation when riding through very powdery, talcum-like sand and noted reduced braking efficiency something like described on one occasion.

    Perhaps a good cleaning several times throughout the winter or during storage periods. I wouldn't squeeze the brakes until cleaned to possibly test the theory. I simply can't think of any other possibility that would contribute to this problem.
    Definitely not a dust issue with mine, the bike's been ridden only in the winter, partly in snow, too.

    I have a buddy working for Shimano and he'll ask their support guys if they've heard of this before. He said they have such few warranty cases that practically every warranty case is approved.

    A friend bought a mountain bike last year with XTR brakes that were like a year or 1.5 years old and they were just like mine, lacking in power. And the previous owner took the bike to the LBS for regular services, so I don't think he was the neglecting type. This friend of mine got the brakes serviced. She has no previous experience in disc brakes, so she has no idea how powerful they should be. Hence it's a little difficult to check with her, if they work perfectly now. She's also the type who'll just pay to get her bike serviced, so she won't know what was done to the brakes to fix them.
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    Quote Originally Posted by dth656 View Post
    thanks for the feedback cleared2land. both levers that were bled feel crisp, and not spongy at all, so everything good there. it's more the lack of power in braking, or as you said, it feels like the coefficient of kinetic friction between the pad and rotor is much less now, leading me to believe its pad contamination.

    i'll order new pads and a shimano bleed kit on monday (having watched quite a few videos on bleeding shimano brakes), so henceforth, i'm hoping to just service them myself.
    Hmmm...I guess that I'm a little confused. You say that your brake levers feel crisp and not spongy at all. If that's correct, then there is no reason to bleed them. Bleeding them will not offer anything better than you have right now. If in fact your issue is in the pads (contamination) then you need to address that issue, not bleeding.

    If you have metal pads, you have an option available to you that is not recommended for resin pads. Baking them. You can scrub the pads with acetone, MEK, or alcohol and place them in the oven to bake. Everyone seems to have a slightly different "recipe" for doing this in terms of how hot and how long. A brief search here should yield you some additional information on that. I would try that before dropping the money on new pads. If that fails, then you were getting new pads anyway.
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    I'd like to point out another culprit that can contaminate front brakes...

    I've had an instance where my fork was slowly leaking oil onto my front brake. It is also an XT M785 and I lost all friction between the rotor and the pads, but the lever felt fine. I took it for a ride and the friction eventually came back to 100%, but on my next ride it was slippery again. I cleaned my rotor and installed new pads and also installed new crush washers for my RS Pike's lowers and everything was back to normal.

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    I also had the same problem when the bike sits over winter. I simply took my pads out, put them in the oven at 350 degrees for 10 minutes. Let them cool, reinstalled the pads, and never had another problem...

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    ooops, sorry i should have been clearer. i took the bike in because both brakes did need a bleed, but they were otherwise fine (i.e. full power and modulation). the bleed successfully addressed the lever feel, but at the expense of the front brake being contaminated.

    i would only purchase the bleed kit to keep handy for future use (to avoid the LBS from now on!)
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    Interesting note...when I had Avid Elixers, the nessesity to bleed was an ongoing issue, so I sprung for a professional bleed kit and learned to become really good at bleeding those silly Elixers. Finally, I got so tired of the ongoing problem that I sprung for Shimano XT's. In 4000+ miles, I have only had to bleed them one time. WOW!

    The moral of my story DHT, is that you might never need that bleed kit that you're buying. But, I would definately suggest you buy one just in case.
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  30. #30
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    Quote Originally Posted by rfxc View Post
    What happens to shimano brake pads when my bike sits in the basement for 6-8 weeks without riding? Help me, I'm baffled.

    Backstory:
    In the last 2 years, my wife have had over 7 bikes in our house each with either Shimano M98x or M78x brakes on them. They either came stock on a bike, or I bled them and installed them myself.

    We'll ride a bike for couple months in the fall, brakes work great-- quiet, powerful, zero drama. put the bike in the basement for a couple months, pull it out in March to ride, and boom-- brakes squeal like crazy, less grabby, less power. Bikes are stored right side up, in various parts of my basement, leaning against a wall, etc.

    This has been happening on various bikes. Various pad compounds, organic and metallic, finned and not finned. Genuine Shimano and truckerco pads.

    Removing and sanding sometimes helps, but often only for a minute or two-- full power just doesn't return.

    My solution is to buy cheap (truckerco) pads in bulk and replace when this happens.

    My LBS has said the same thing about their XT equipped demo/rental bikes that sit for a month plus without use. What gives?

    What the heck am I missing? Please share your well thought out hypothesis.
    Easy... check for fluid leaks. I'm fighting the same issue right now.

    I'll bet pot brownies to poundcake that if you took the pads out and hit them with a torch, they would smoke off a bunch of brake fluid. Try that, and cleaning the rotors with brake cleaner. The brake cleaner or isopropyl alcohol will leave a bit of a residue that burns off after a couple hard stops. Throwing out brake pads because of brake fluid contamination is like throwing away clothing instead of doing laundry.

    And, I'm not convinced that bleeding brakes will do anything for this issue. If the issue is that the seal is contaminated with a speck of dirt, allowing fluid to seep out, then sometimes you get lucky by being able to clean the seals (brake fluid on q-tip around the extended pistons and seals as much as you can reach) but that is really a hail mary.

    Yeah, and brake bleeding is pretty easy, especially with Shimano brakes. You just need a bottle of brake fluid (I bought the liter size for $25... lifetime supply!) a 7mm wrench and a bit of 1/4" ID (IIRC... might be 3/16") clear vinyl hose you can get from the hardware store. You will also need the little yellow plastic block that goes in the caliper to set the piston spacing/system fluid volume correctly. Just make sure you chase all of the air out of the reservoir with the rubber bladder. I say do it a couple times, and you'll get a feel for it. No need to bug the LBS for that one.

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    I have the exact same issue as the OP. Still have to try some of the remedies but glad to see I'm not insane. My bike is also stored indoors, upright and kept clean. Bought the brake set last season (XT and IceTech). It's a little disappointing as I've loved the brakes until now. Will keep this thread posted on what works.. or not.
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    Some folks seem to be getting positive results from baking or torching. Several threads or comments around. Should be able to find some good information.
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    Thanks folks, keep the stories coming, maybe we'll find a remedy.

    I started this post because I believe somehow the pads soak in moisture from the air, something, to get contaminated or glazed after use then sitting idle.

    My lbs reports similar stories, they have slx/xt/xtr demo bikes that will get used every couple months, and after sitting idle, the pad/rotor have very poor friction.

    I should also mention, I live in the midwest, so our climbs are short, rarely are you braking long enough to "burn off" anything.

    My wife took her pads out, sanded them, then put them in the oven at 450deg for 30 mins, pads came back to life. Huh.

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    Took off the pads last night and the braking surface was quite black. A little sanding (used a sharpening stone just 'cause it was handy and flat) brought them back to the normal tan/copper coloring. Cleaned the rotor with some alcohol and it definitely felt better riding around the basement. Hopefully will get out this weekend (banged up my leg crashing so I've been off the bike a couple weeks) and see if it holds up. Probably try the oven if this doesn't work. I'm sure the wife will give me the WTH are you doing NOW?! look.
    Thanks.
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    Similar problem here - poor braking after the bike was put away for a couple of months - one pad was pretty dark. Took them off and put them in the BBQ - once they stopped smoking I sanded them a bit, and now no more problems. I suspect a leaking caliper (potential Shimano defect?). This is on a set of 9 month old SLX675's. The front brake has already been replaced under warranty by Shimano - I suspect the rear has a tiny leak...

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    Add one more person to this issue except that one day it was fine and then next it wasn't.
    Seached the inter-tubes and decided that it could be the hose and/or banjo bolt on the caliper. Bought a new set of hoses and fittings from Jagwire, installed them, sanded the pads and rotors and did a few runs down a steepish hill by my house to bed them in and the squealing and lack of power have disappeared.

    Hopefully, that is the end of that. I do appreciate how unbelievably simple shimano brakes are to bleed compared to Avid/Elixirs.

  37. #37
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    I've experienced the same thing. I also suspected leaking oil at first but I don't believe it is the case (I couldn't see any trace of oil). I suspect it is just a case of the pad material reacting with the air, such as an oxidation reaction or something like that.

    It was happening on my front brake which is an XTR 1 piece caliper with F03C pads (metallic ice tech), but not on my rear brake with an XT caliper and B01S pads (resin, not designed for this caliper, but they work and I can get them free).

    The usual fix was to just ride and use the brake. I have gotten used to dragging the brake for a bit when starting a ride before I would need to do any actual braking, so that there would be some power. I believe this is normal for disc brakes. Some automotive brakes drag all the time to prevent this from happening, but obviously we don't want that on a bike.

  38. #38
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    Same here for me with XTR. Bike sat for 4-5 months in the basement. I was forced to ride it today, no power and howling.

  39. #39
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    I just had an experience with this that might be relevant. 2014 SLX brakes, but obviously similar to the XTs. Bike hadn't been ridden for a while, and had very weak stopping power and loud squeal under all conditions. Brakes had been completely normal on the last ride a few months back. I went out on a ride anyway. Horrible braking for the first 30 minutes of the ride, then I hit the downhill section. For the first mile of downhill there was no change, then over a 30 second stretch they were back to full power and normal. They weren't particularly dirty or dusty; stored inside; never above 80 degrees.

    For those of you with similar issues, you might just get out and ride it for an hour. Put a pretty good load on them, get some heat in them, see what happens...

  40. #40
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    Yep. Thanks folks for helping me feel like I'm not crazy.

    Between wife and I, 5 bikes have latest gen shimano brakes in my house, 2x XTR, 2x XT, 1 SLX. Wife put the perfectly running XC bike aside for 6 weeks, rides the enduro bike, gets the XC bike out of the basement... sure enough, squealing, etc. It's happened to both of us with different bikes, organic and metallic pads from shimano.

    I can only assume that pads somehow glaze over or oxidize while sitting unused, and that has to be burned off in a long and noisy bout braking-- which is hard to come by in Omaha, where the longest descent around is maybe 90 seconds

    Should I have any reason to believe that swiss stop or kool stop brand pads would behave any different? I'm tempted to try.

    Sanding & baking our brake pads every time a bike has been sitting idle for 6 weeks is kind of a PITA.

  41. #41
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    I now have this same problem. It was never a problem with the facotory Deores or with the metallic, finned pads swapped in the Deores (or maybe the bike never sat that long when it was brand new).

    Now that I've had the Zees on for a while I've noticed that if it sits for more than 2 days, braking power is gone. It doesn't come back with the first stop as the pads warm up. Heat seems to have nothing to do with it. I have to drag the brakes for quite a long time and then all of a sudden in a matter of seconds I'm at full braking power again and it stays that way even if I let the bike sit for 5 hours and come back to it.

    This has to be some sort of change happening to the pads while they sit. I washed the bike for the first time the other day and dried it well, using compressed air in cracks and crevices plus I rode it and dragged the brakes to get them hot. The next day they were the worst they've ever been . I'm convinced it's some sort of oxidation. Hopefullly my LBS carries Saint/Zee pads. I'm going to switch to the finned organics if they make such a pad for the Zees, just to prove it's a pad issue.

    The rotors look normal. No oxidation and a nice transfer layer laid down. No brake fluid contamination. I've pulled the pads off before and after re-breaking them in and the pad surface looks slightly different before and after.

    I love Shimano brakes and I have no plans on jumping ship but they really dropped the ball with this latest round of pads with the pad material falling off and now oxidizing. My dog ran out in front of me as I was leaving the house and these brakes normally have huge power so I grabbed the brakes and I had little stopping power. I finally had to squeeze them so hard I thought I was going to break the lever and I barely stopped in time. Normally I can endo or lock the front tire on concrete with one finger and not much effort. The incident with the dog was the first time it happened so I was kind of pissed.

    Just to clarify, the lever feels normal. This is not air in the system or an alignment problem nor a slave or master problem, it's a friction problem.
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    Same. Around 12/2014 I put one of my bikes in the garage, with at the time, brand new XT brakes with the finned resin pads. They worked perfect when I hung it up. Got it out the other day and now they barely work, and squeak like a mo-fo. I cleaned the rotor and a bunch of black grime came off. Applied brakes again and rotors were all grimey again.

    I had a pair of metallic pads from another bike and installed them and the brakes now work perfect.

  43. #43
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    I would have to assume a bike that has been in storage and not ridden for 10 years could exhibit a number of problems. You're surprised?
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  44. #44
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    Quote Originally Posted by Cleared2land View Post
    I would have to assume a bike that has been in storage and not ridden for 10 years could exhibit a number of problems. You're surprised?
    Hey at $20 a pair, I expect my brake pads to last at least 15 years. Good catch though, 2014

  45. #45
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    Every pair of the current generation aluminum caliper XT or XTR brakes I've owned have done this. One set would leak enough oil out the pistons to make accumulated snow on the caliper yellow. Strange though that it's not enough fluid to need frequent bleeding.

    I've now had two pair of the XTR M-987 Magnesium caliper brakes, they do not have the same problem. My favorite brakes, ever.

  46. #46
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    To follow-up, I took sandpaper to the pads and the brakes now work perfect. I am assuming they were more covered in dust then any type of oil. When pads are contaminated with oil, sand paper almost never works.

  47. #47
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    Mine did the same thing sitting for 3 months over the winter (fronts worse than rear), in my basement which is cool and mostly dry. After sanding they did wake back up, I'll bet it's a thin layer of corrosion on the metallic pads. I know copper can get a thin slick green layer on it, so maybe something similar is happening. Baking would work better than sanding because it turns the corrosion from slick to dust that can burn off more easily, and dry out any moisture accumulation that's deeper into the pad material. Sanding would just remove the upper layer, but you'd have to sand a lot to get it all. If baking them is the answer after sitting, it shouldn't take more than 250f to dry them out. If it is a layer of oxidation; putting a rubber band or strap around the lever while stored to keep the pads on the rotors would keep them out of the open-air, and maybe slow/stop the oxidation? -just my 2c.

  48. #48
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    I also have the same problem, I'll see how it goes after the first rides when snow will melt. I also remarked something : my levers are kind of oily after sitting there for a while; not only the levers but it's kind of oily near the freestroke adjustment screw and the reach screw. Nothing is dripping or accumulating, but there is enough oil to want to wipe it off with a rag. I don't feel any loss of power when squeezing the brakes. Does anybody has that on their brakes too ?
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  49. #49
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    I've also just suffered this problem but my bike only stood for 3 weeks. It was also only the rear brake. Just identified that the bleed nipple was passing fluid slightly. Found out by cleaning everything up and then using a cable tie to lock the brake on. I'm getting a new set of pads but worth checking the bleed nipple isn't leaking.

  50. #50
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    In my experience, the brakes in question only squeal when mineral oil gets on the pads. I've had it happen once by accident (my fault), and a second time due to a faulty caliper piston seal on my new road bike. I kinda doubt dust is the issue.

  51. #51
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    Great follow up guys. I'm still dealing with the issue, but I've gotten pretty quick at removing and cleaning pads on a bike after it's sat idle for awhile. Most of the time, sanding is not adequate. But after a quick hit with a propane torch or my natural gas stove and they are fine.

    couple interesting points above.
    Brentos says it doesn't happen with his 987 magnesium caliper brakes. Interesting. This supports the notion that there may be a slight design flaw in the 985/785 brakes where oil (very slowly) creeps out around the pistons and contaminates pads after a time. Seems most likely this is whats happening.

    another idea presented above. store the bikes with a rubber band on the lever, keeping the brakes compressed. Question: will storing bikes with the brake lever depressed put more pressure for oil to seep out of the caliper/piston area, or will added pressure and movement/changed position of the piston/seal prevent oil seepage?

  52. #52
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    Quote Originally Posted by rfxc View Post
    Great follow up guys. I'm still dealing with the issue, but I've gotten pretty quick at removing and cleaning pads on a bike after it's sat idle for awhile. Most of the time, sanding is not adequate. But after a quick hit with a propane torch or my natural gas stove and they are fine.

    couple interesting points above.
    Brentos says it doesn't happen with his 987 magnesium caliper brakes. Interesting. This supports the notion that there may be a slight design flaw in the 985/785 brakes where oil (very slowly) creeps out around the pistons and contaminates pads after a time. Seems most likely this is whats happening.

    another idea presented above. store the bikes with a rubber band on the lever, keeping the brakes compressed. Question: will storing bikes with the brake lever depressed put more pressure for oil to seep out of the caliper/piston area, or will added pressure and movement/changed position of the piston/seal prevent oil seepage?
    Another thought - If you take apart one of the two piece calipers there is only a small O ring that seals the passageway between the two halves. It didn't appear to me that its under much compression. Maybe when the bikes sit for a while the O ring shrinks a little and seeps fluid. My bike is always stored upside down, so fluid doesn't run on to the rotors. If you store it right side up the fluid would drip on to the rotor.

  53. #53
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    I've had M775s, M596s and M395s all do this to me and it drives me OUT OF MY MIND.

    After they sit for a few weeks, they squeak and there's no bite, but the levers are plenty firm. It's like they glaze over when they sit.

    I'm inclined to believe it's not oil leakage; after some riding, they return to full power.
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  54. #54
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    I too have experienced the same problem as many here after extended periods of no riding on many occasions (I have three bikes with XT's installed, so they see some periods of storage). Firm on the lever pull, but an initial reduced braking effect. However, for me personally, the problem quickly goes away with a few hard braking attempts much like you would do when bedding new pads. Problem solved.

    I have no idea if it's dust, oxidation or whatever...but it's a minor inconvenience at worst. All this talk of leaks and seeping calipers is seemingly a little over the top and can be quickly diagnosed with a quick look. It seems this is a big deal to some, but they might be experiencing different problems. But it does seem to be the same problem.
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  55. #55
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    Quote Originally Posted by Cleared2land View Post
    I too have experienced the same problem as many here after extended periods of no riding on many occasions (I have three bikes with XT's installed, so they see some periods of storage). Firm on the lever pull, but an initial reduced braking effect. However, for me personally, the problem quickly goes away with a few hard braking attempts much like you would do when bedding new pads. Problem solved.

    I have no idea if it's dust, oxidation or whatever...
    Exact same experience on my wife's XT (M785) equipped bike. I looked and it has metallic pads. I look like an idiot on her tiny bike, but I go up & down the street about 10 times and burnish her pads to the rotors. They work just fine afterwards.

    The last time this happened, I could actually see some discoloration on the front rotor. The rear was shiny and worked better, but the front was not grabbing well at all and when it did start to work I could see some shiny grooves in a darker pall. I think that's some kind of oxidation.

    I'm shopping for resin pads now. I am not sure if she is using icetech or standard rotors... been a few years since I built this thing. But I think it's the stock Shimano semi-metallic pad, so I'm starting there.

  56. #56
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    Quote Originally Posted by ColinL View Post
    I'm shopping for resin pads now. I am not sure if she is using icetech or standard rotors... been a few years since I built this thing. But I think it's the stock Shimano semi-metallic pad, so I'm starting there.
    I've had it happen with both resin and metallic.
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  57. #57
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    New data point. I finally got a new set of metallic Ice-tech pads for my Saints, which were working totally fine on the old and now worn down pads. Cleaned all the dust & crud out of the calipers, put the new pads in, got them bedded in nicely and a couple days later they had no braking power. Burned them back in with a few hard stops and they were back to full power, put them away overnight and most of the power was gone. Decided I didn't want to deal with this crap anymore and popped in a set of metallic M810 Saint pads and everything worked as it should with no power loss after storage. So it's definitely the pads, not a leak in my brakes. I figure I'll just save the Ice-tech ones for DH days where I can quickly burn them in on the first run.

    For what it's worth my original pads came with the brakes which were ordered from Europe a couple years back. The new pads came from Shimano's North American warehouse in the US.

  58. #58
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    Quote Originally Posted by eicca View Post
    I've had it happen with both resin and metallic.
    Hmm. Is it the icetech rotor oxidizing?

    Isn't it some kind of aluminum and steel sandwich?

  59. #59
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    I had this exact same issue with 2 sets of SLX and Saints, both latest generation. The Saints were the worst. The bike was in a dry, cool basement for wintertime (fat bike season) and when I rode in spring there was zero bite and power. I Cleaned the rotors and sanded a bit of the surface of brake pads, but the power never came back. I checked for leaks, but there was none.

    With 2 sets of SLX, XT and Saints all lost power and bite after use, slowly but Gradually. I've heard few others reporting the exact same issue.

    After these experiences I went for Hopes for my latest build.

  60. #60
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    Quote Originally Posted by ColinL View Post
    Hmm. Is it the icetech rotor oxidizing?

    Isn't it some kind of aluminum and steel sandwich?
    It's definitely not the rotors since I run standard steel rotors on my bikes, and only use the Ice-tech rotors for DH days at the bike park.

  61. #61
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    Quote Originally Posted by aerius View Post
    It's definitely not the rotors since I run standard steel rotors on my bikes, and only use the Ice-tech rotors for DH days at the bike park.
    Ok, excellent to know.

    People are saying it happened to them with both organic and semi-metallic Shimano pads.

    What about non-Shimano pads? There are a variety - Galfer, TruckerCo, Jagwire and so on. I'm curious if someone has put on 3rd party pads and whether the issue remained or was corrected.

    It has to be something specific that we can narrow down...

  62. #62
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    I have an older set of XTR's on my Prophet. If it sits for a long time, I get the same thing. It happens with Shimano pads and Truckerco pads. After a Brake Clean spray and wipe and some high speed street runs with frequent stopping, the squeal goes away and the power returns. I am currently using Truckerco pads. It seems to have nothing to do with the calipers. In my experience, when oil gets on the pads there is no saving them, they are junk. This is a different phenomenon. Perhaps as the disc brake community has expanded and grown there is a slime mold organism that has made disc pads there preferred home? A new species? Evolution!
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  63. #63
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    I have to comment here regarding this issue.

    I have experienced the reduced braking as I stated in an earlier post, but I have NOT experienced any noise or squealing in the process. Brakes remain quite, but with reduced braking ability.
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  64. #64
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    I wouldn't condemn the resin pads yet. Just one person has had the issue with them and he also has a squeal which isn't really a normal symptom the rest of us are having. The noise plus loss of power usually points to contamination.

    For what it's worth, the Zee/Saint "resin" pads have a good bit of metallic content. I would call them a semi metallic more than a resin pad. They have been flawless no matter how long the bike sits. The sintered pads on these brakes had the issue way worse than the sintered on my XTs. It could be due to the extra surface area of the Zee pads, it would definitely take longer to wear off any oxidation layer.
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  65. #65
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    I have this problem as well. While it generally seems to resolve itself after a brake heavy ride, a recent pair of resin pads has been giving me a he!! of a time. Finally blasted the pads with a propane torch. After a quick bed in loop around the block they seem back to normal. Time will tell.

  66. #66
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    Same problem here! Only the rear on XTR M988. The front feels great. Rear HOWLS and has no power after sitting for the winter. I put new pads (Kool-Stop) in last fall because the stock pads are garbage. I'll try torching the pads.

  67. #67
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    Anybody try doing the figure 8 on a piece of sandpaper to freshen up the pad?
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  68. #68
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    Quote Originally Posted by Bent Wheel View Post
    Anybody try doing the figure 8 on a piece of sandpaper to freshen up the pad?
    No, but sprinkling a little lemon water on them freshens them up nicely.
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  69. #69
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    I have taken my pads out and run them over a sanding block a couple of times, along with sanding the rotor with really fine grit paper. That has helped, and my brakes are working well now. I'm going to try baking them next time I let them sit for a long time. Schmucker: did yours come with the metallic pads? I can't imagine not liking those.

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    Another 987 user here, no issues after all winter of sitting in my basement. Are the pads the same between 985 and 987?

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    I had/have the same problem on my 2014 Slx m675 brakes. Had the bike sitting over the winter, when I took it out again no power. Cleaned the pads (resin), used sandpaper, scuffed the rotors, tried to re bed them. After sitting for a few weeks power was lost again and I sometimes had to pull very hard to stop at all. Especially the rear brake did squeal/howl on those occasions. Did this twice and after a longer ride they now seem to be halfway back to normal, but power is still subpar when compared to other SLX brakes on a buddies bike.
    Has anybody tried to claim this to Shimano? I guess they would put it off as contamination, but maybe worth the try.

  72. #72
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    Interesting that I have experienced the same issues as everyone has described, but I have never sanded rotors or pads. A few hard braking maneuvers as if bedding in new pads and everything was like new. All of this sanding seems a bit overzealous.
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  73. #73
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    I've been riding to work for a week now and so far my front brake had kind of returned to normal. Still a little noisy and feels weaker than usual. My back brake is still just as bad as when I first got my bike out. Pisses me off. I can't see any evidence of leakage so far, I'll pull the pads and sand them and see if I can't get them worked into shape. Maybe they're "glazed" so bad they can't generate enough heat to wear down.

  74. #74
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    Also, I was just chatting with my mechanic friend about this case and he says the only thing he can think of that would cause what we've been experiencing is dust collecting on the pads and then burning and glazing when going for a ride. I'm inclined to think this is worth further thought since nothing else really make any sense

  75. #75
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    Further update: I pulled my pads and they looked glazy, like a donut. So I sanded them, 32 small circles each facedown on the sandpaper. The difference was very visible. I cleaned the rotors with alcohol and reinstalled the pads, and now they feel just like brand new brakes needing to be bedded in. Night and day difference.

  76. #76
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    Quote Originally Posted by eicca View Post
    Also, I was just chatting with my mechanic friend about this case and he says the only thing he can think of that would cause what we've been experiencing is dust collecting on the pads and then burning and glazing when going for a ride. I'm inclined to think this is worth further thought since nothing else really make any sense
    It's not likely dust as mine would lose power as quickly as 24hrs after my last ride sometimes. Mine weren't so horrible until I got the brakes good and hot one day but maybe that's just my bad memory.

    I always wanted to try sanding them because I figured it would speed up the process but after almost running over my dog I swapped to resins and never looked back. Power was so low that I couldn't lock up the rear tire on a brake that's usually so powerful I can put myself over the handlebars easily with one finger. It really was a safety issue with how much power mine lost when sitting. When my dog ran in front of me it was t even close. I hit both brakes, no power, so I put my feet down. It was worse than my Tektro mechanicals on 160mm rotors.
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  77. #77
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    I'm now 100% certain the pads glaze themselves while they sit. I can feel the difference between coming home from work and then riding the next morning. They literally foul up overnight. I pulled the pads and inspected the calipers and they're bone dry. No leaks. This is driving me INSANE. I wonder if Shimano will warranty them.

    Has Shimano acknowledged the issue? Offered any kind of statement? Anything?
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  78. #78
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    Try just sanding the pads and don't clean the rotors, see if that helps. Rebedding may be having an ill effect on the pad after sanding them.
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  79. #79
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    Quote Originally Posted by Bent Wheel View Post
    Try just sanding the pads and don't clean the rotors, see if that helps. Rebedding may be having an ill effect on the pad after sanding them.
    I'm willing to give it a try. Tell me more about your thought process though; would leaving pad material on the rotor transfer it back to the pads and prevent glazing?

    I feel like this issue has consumed my life. It's like CSI: MTBR or something.

  80. #80
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    Just sprinkle pixie dust on your calipers before bedtime and everything will be fine in the morning.
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    I don't think you can prevent glazing totally. I do think that cleaning the rotor and rebedding is causing the quick glazing issue you are having. I don't clean my rotors, so I haven't experienced this quick glazing issue. I've only sanded my pads once in the 6 months I've had them. Give it a try, we both might be surprised.
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  82. #82
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    Just one quick point, the pads can't glaze by definition while sitting. That's why I believe it to be corrosion or some chemical change after getting hot and being exposed to air while sitting. I hope it has nothing to do with the aluminum/stainless sandwich of the rotors. I think earlier in this thread someone had removed the pads after a ride and they still had the problem but I don't remember for sure.

    For a brake to work properly the pads must lay down a transfer layer on the rotor. Once this is done, wear (rotor and pad) and noise drop greatly and power is much improved. By always removing this layer you're starting all over all the time. I'm not sure it has anything to do with this particular problem but a transfer layer is important. Hell, maybe the transfer layer on the rotor is what's changing while sitting.
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    Quote Originally Posted by Bent Wheel View Post
    Try just sanding the pads and don't clean the rotors, see if that helps. Rebedding may be having an ill effect on the pad after sanding them.
    Tried it out of curiosity today, it works. I gave the pads a quick sanding with 400 grit sandpaper, sanded it just enough so that a bit over half the pad was showing the nice copper colour of the metallic compound. I did not do any cleaning of the pads or rotors. I had about 80% power on the first stop, and full power within 4-5 stops. It remains to be seen if the pads will keep going to shít overnight and if the sanding needs to be done before every ride.

    I can confirm that it has absolutely nothing to do with the rotors or calipers since I use the regular all steel rotors on my bikes and have pulled the pads and put them into storage immediately after a ride. And yet I still have the issues.

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    Wow, lots of problems with the Shimanos, maybe five years from now people will be hating on Shimano brakes and loving SRAMs, especially given the new Guides....


    Before you flame me, just think about this and the last 15 years of bikes brakes, also I love my XTRs and I am hoping I do not get the chance to experience this new problem.

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    I've got a XT equipped Santa Cruz Superlight 29er that has become a spare (extra) ride for visiting friends. It doesn't get ridden too often and I just took it out for a trail ride and it seemed to have minimal, but notable brake fade and was initially braking at about 85%. Several hard braking applications seamed to restore the brakes back to 100%. That seemed easy enough. My regular ride has XT's and I used it as my benchmark braking comparison.
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    Quote Originally Posted by Havinfun View Post
    Wow, lots of problems with the Shimanos, maybe five years from now people will be hating on Shimano brakes and loving SRAMs, especially given the new Guides....


    Before you flame me, just think about this and the last 15 years of bikes brakes, also I love my XTRs and I am hoping I do not get the chance to experience this new problem.
    You really have a hard time understanding the most basic things based on this and your previous postings. There seem to be a bad batch of finned metal pads. These Shimanos are not leaving people without brakes. No frozen Pistons or levers that go to the bars. A bad batch of pads is way different than 10+ years of bad brakes. The Avids should have been sold as disposables. Buy a 6 pack and replace once or twice a year when they fail on you. These have lower power after sitting for the first mile or two before wearing off the layer of corrosion and getting full power back. If Avids only had issues with pads they wouldn't be despised by so many. This is one minor problem and it is with the pads.
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    Quote Originally Posted by aerius View Post
    Tried it out of curiosity today, it works. I gave the pads a quick sanding with 400 grit sandpaper, sanded it just enough so that a bit over half the pad was showing the nice copper colour of the metallic compound. I did not do any cleaning of the pads or rotors. I had about 80% power on the first stop, and full power within 4-5 stops. It remains to be seen if the pads will keep going to shít overnight and if the sanding needs to be done before every ride.

    I can confirm that it has absolutely nothing to do with the rotors or calipers since I use the regular all steel rotors on my bikes and have pulled the pads and put them into storage immediately after a ride. And yet I still have the issues.
    That's really good to know, I really didn't want to give up my ice tech rotors. I think by your sanding the rotors with no other changes during the problem it proves it's the pads only. The slightly reduced power at first would be normal break in.
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    Quote Originally Posted by Cleared2land View Post
    I've got a XT equipped Santa Cruz Superlight 29er that has become a spare (extra) ride for visiting friends. It doesn't get ridden too often and I just took it out for a trail ride and it seemed to have minimal, but notable brake fade and was initially braking at about 85%. Several hard braking applications seamed to restore the brakes back to 100%. That seemed easy enough. My regular ride has XT's and I used it as my benchmark braking comparison.
    By fade, you're talking about lost power from the layer of corrosion, not actual heat induced pad fade, right?
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    Quote Originally Posted by BuickGN View Post
    You really have a hard time understanding the most basic things based on this and your previous postings. There seem to be a bad batch of finned metal pads. These Shimanos are not leaving people without brakes. No frozen Pistons or levers that go to the bars. A bad batch of pads is way different than 10+ years of bad brakes. The Avids should have been sold as disposables. Buy a 6 pack and replace once or twice a year when they fail on you. These have lower power after sitting for the first mile or two before wearing off the layer of corrosion and getting full power back. If Avids only had issues with pads they wouldn't be despised by so many. This is one minor problem and it is with the pads.
    You are consistent. There are these problems, your problems with your Zees, the problems with squealing... But, you cannot have a conversation without trying to insult and you cannot own any problems. The best part is that it is so easy to get you worked up. Do your best insults, be the jerk you can be (not always, just when you don't like the opinions of others), but the fact is that Shimanos have multiple issues. In the end, though, both Shimano and SRAM have great products overall and that appears difficult for you.

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    This behavior is not at all random, I have been through 3 pairs of breaks. Sent one of them to Shimano for warranty, they did replace Deore M596 with 2014 model. This riding season of 2015 and same exact problem, loss of breaking power, squeal. Exactly as 2013 model. I check very careful and do not see pad contamination. Shimano does not acknowledge the problem. They keep denying all photographed/documented facts that with winter glazing, with bleeding nipple that has tiny bit of sipping (yes torque to spec the nipple). Both 2013 and 2014 leak at the nipple but calipers are dry. Pads are clean from any mineral oil. I will keep sending to Shimano given that it has 2 year warranty and they need to really accept that they have an issue. If nobody complains then why would Shimano fix anything?

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    Quote Originally Posted by dvzzz View Post
    This behavior is not at all random, I have been through 3 pairs of breaks. Sent one of them to Shimano for warranty, they did replace Deore M596 with 2014 model. This riding season of 2015 and same exact problem, loss of breaking power, squeal. Exactly as 2013 model. I check very careful and do not see pad contamination. Shimano does not acknowledge the problem. They keep denying that fact that bleeding nipple has tiny bit of sipping (yes torque to spec the nipple). Both 2013 and 2014 leak at the nipple but calipers are dry. Pads are clean from any mineral oil. I will keep sending to Shimano given that it has 2 year warranty and they need to really accept that they have an issue. If nobody complains then why would Shimano fix anything?
    You are probably going to be told that you are wrong and that you have never actually had these problems. Then, you might be insulted. Then maybe attacked, given the Shimano Fanboys can get that way.
    But, the reality is that few people have problems with the Shimanos, usually they are great. But, like everything today, some will fail. And, some people will get the bad luck of having a few fail.

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    Quote Originally Posted by BuickGN View Post
    By fade, you're talking about lost power from the layer of corrosion, not actual heat induced pad fade, right?
    Yes, that is correct. The initial fade or loss of braking power experienced at the beginning of a ride on a bike that has not been ridden for a while.. Weather it's corrosion, or whatever, I'm not sure of. I do know that for me personally, It's not a significant issue.
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    My bike has been sitting all weekend due to nasty cold rain. I fully expect to have crappy braking performance tomorrow. I'll try sanding just the pads and see if that changes behavior. If not, I'll get 'em warrantied and see if I can upgrade to a newer set and throw in some aftermarket pads.

    Will post back with results.
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    For what it's worth, after riding my bike for the first time since winter, the brakes suck ass again. Damn near dangerous.

    Last time sanding them did the trick. I'll try it again.
    Last edited by matto6; 05-12-2015 at 09:29 PM.

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    Been riding on Shimanos for the past 7 years and am now running on the XTR M9000 Race brakes. Only once have I experienced such a problem and that was with mettalic pads after a bike clean where I might have gotten a bit of spray stuff on the rotors. The past 4 years I only used the Resin pads and have not experienced this problem, except from my brakes needing the occasional bleed or a change of pads.
    I ride everyday through all kinds of weather.

    Just check where you store your bike, how you clean and wash it and cotrol from time to time if you need new rotors, pads or a bleeding.
    Oh and never in my life did I have the need to wash or burn or sanding my rotors.
    Im not saying that there are no problems with the brakes, hell in the past they had quite a few issues with brakes leaking but that seems to have been improved a lot.

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    Quote Originally Posted by Havinfun View Post
    You are consistent. There are these problems, your problems with your Zees, the problems with squealing... But, you cannot have a conversation without trying to insult and you cannot own any problems. The best part is that it is so easy to get you worked up. Do your best insults, be the jerk you can be (not always, just when you don't like the opinions of others), but the fact is that Shimanos have multiple issues. In the end, though, both Shimano and SRAM have great products overall and that appears difficult for you.
    Once again, instead of trying to say I'm wrong with facts or at least a factual based argument you get all emotional. You made a statement of "Wow lots of problems with Shimanos......". Not lots of problems. The same problem in almost every case which would be a problem with the pads, not the brakes themselves. You're so quick to make a blanket statement as if Shimanos have tons of problems. Leave your emotion and bias out of it and we can have a conversation. A bad batch of pads does not compare to all of the Avid brake failures that occurred over the past 10 years. I can't believe you would even go there. The Guides hopefully will prove to be reliable but only time will tell. It's been long enough that I'm going to finally pull the trigger on a set but I'm still a little leery of going with Avids again.

    I can't admit problems with my brakes? I've stated every problem. The metal pads squealed and had no power but when I dug deeper I found that they were bent. What's the problem? I don't think we can blame Shimano and we definitely can't blame the brakes.

    My Zees weren't bled properly when I got them so I bled them and they've been trouble free ever since, almost a year now.

    I've been very vocal about the pads that corrode when sitting and lose power until I've ridden several miles.

    I've inquired about the aluminum sandwich rotors melting and started looking into other brands' stainless 2 piece 220mm rotors. After the recent descents, I've realized that I can't get my rotors to melt if I try so I'm sticking with what's on the bike but I was about to jump ship until I dug deeper.

    I'm sure I will be called a jerk for stating that I don't hate Shimanos lol.

    To you, an insult is presenting facts that go against your beliefs so I'm not too worried about those accusations. You have at least 2 threads right now unprovoked throwing out insults to "Shimano Fanboys" and something about dying a slow death that myself nor other Shimano owners have posted in. They're just a chunk of metal, I don't have some undying loyalty to them as you seem to have.

    I don't care if you have opinions no matter how wrong they might be but you state them as facts and that's where the problem is. I've given the Guides several good reviews, I'm getting ready to use them on my XC bike as I've stated numerous times but I can't admit that Avid has good products? Get over yourself. You've created this little battle of Avid vs Shimano. I've always kept my posts factually based and when I have an opinion I state it as an opinion and I usually explain how I arrived at that opinion or conclusion so others might be able to tell me if I'm right or wrong.

    You on the other hand love to keep everything subjective and you flip out when there's a fair objective apples to apples comparison and your brake doesn't come out on top. I'm not the one comparing one brand's power with 160mm rotors to another brand's power with 203mm rotors. The different sized rotors were not brought up by you, luckily another poster was sharp enough to remember what you were running. You were going to compare the two brakes with drastically different sized rotors and not tell anyone!?!? Maybe a little bias here? Once called out you state that it's fair because the bike with the XTRs is 6 lbs lighter so it evens out!!! Wow. I hope you realize now that, that was an opinion and a severely misguided one. If you had done even a tiny bit of research you would have seen that 6lbs makes no difference compared to the rotor size difference but I don't think accuracy is what you're after....

    After getting called on it and after the pads are bedded in, you say the XTRs are nice but you make no mention of power. You say you can't compare because the bike with the Guides is ridden under different conditions. Different conditions might test out the heat dissipation but all you need is to do a couple stops in your driveway to know which brake requires less effort for a given deceleration rate. It seems like you're purposely trying not to compare the power of the two. Remember, initially you exclaimed that the Guides are way more powerful and anyone who says they're not more powerful has never tried them or has tried both brakes. Once the XTRs are bedded in, you have no opinion of which one is more powerful all of a sudden because of different conditions but the conditions didn't stop you from that opinion at first when the Guides were stronger.

    I would never compare brakes with different sized rotors and pads not bedded in, at least not without making it very clear in the comparison. I'm not the one saying 4 piston brakes are stronger than 2 piston brakes and the list goes on and on. You state your opinion as fact and get pissed off when you're proven wrong by actual facts and start calling us jerks. I enjoy learning so if someone proves me wrong it's fine, it means I learned something new. My entire worth as a human being is not centered around whether or not my brakes are the best in the world or whether I'm always right lol.

    It's easy to see what's going on, you seem to have trouble telling the whole truth and you get very defensive when called on it no matter how nicely it's done. My stance between the two brakes has always been that power is so close that power should be the last thing anyone looks at when trying to decide between the two. I've said several times that I can see how some would like the lever throw and feel of the Guides better. There are subjective items, personal preferences which can sway a person either way but which brake has the most power on a level playing field is not subjective, the Shimano 2 pistons do have more power but it's so slight it probably won't matter to most. Who's the fanboy here?

    I'm sure your reply is going to be more of the same. I'm a fanboy and I'm a jerk followed by some emotional knee jerk reaction with no facts to back it up and you will ignore everything said above.
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    I wonder if Shimano is aware of this thread... It might be a good idea to make sure they're aware of this problem if they're not already aware. The resin pads for the Zees are very nice and pretty aggressive for a resin pad but it would be nice to have the option to run metals without being worried about noise and a lack of power. I think there's more than enough complaints with the same problems, some going back a few years, to get them to take action. I know I have $80 worth of pads just sitting in a box that I can't use and the last thing I want is to spend another $80 for pads that may or may not work right.
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    Doing a search on this subject shows several threads starting around 2013 that seem to have the same issues. This is the first one that lists corrosion or even pads as the possible culprit but it looks like this problem might have existed for a while now but has never gained the momentum that this thread has.

    I'm sure we're all in the minority or no one would be buying Shimanos with metal pads and most people run metal pads with no issues at all. But still, there seems to be a definite problem with them that needs to be addressed. If the pads cost $10 like many of the older ones did I probably wouldn't care so much but $80 for a set is too much to blow off or take a chance on.
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    Just as predicted, rode to work and the brakes were slippery and noisy after only a three day sit. So I took them out and sanded them again but did not clean the rotor this time. Rode around and stopped hard a few times and they're back to their old one-finger endo/skid strength. We'll see how long that lasts... I'm calling Shimano if I hav further problems.

    And I did confirm 100% they are resin pads. Says right on the back.

    Before sanding, with visible glaze-over:
    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks-image.jpg

    Sanded the pair on the right:
    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks-image.jpg

    Sanded both:
    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks-image.jpg
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    Thanks for the pics, eicca. The 'resin' pad is of course semi-metallic and this metal is what is corroding. The actual metallic Shimano pads may contain a similar material.

    Earlier in this very thread, others have commented about using non-Shimano pads and still having the issue, but I'm going to try a set of TruckerCo for my wife's bike. I'll bed in the pads very thoroughly.

    BTW regarding leaking calipers, my wife's are fine, but my dad has a set of XT brakes (not sure if they are 785 or previous generation) and both his calipers leak.

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    Quote Originally Posted by ColinL View Post

    BTW regarding leaking calipers, my wife's are fine, but my dad has a set of XT brakes (not sure if they are 785 or previous generation) and both his calipers leak.
    The XT M775s were somewhat notorious for leaking calipers. I had a set and blew the rear piston seal at the top of a canyon. Sketchiest downhill run of my life

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    And it's confirmed, sanding is only a temporary fix and will be required before each ride if the brake pads have gone unused for a while. I rode the same pads today which I fixed via sanding a couple days and they're back to squealing with no power. Did another quick sanding on the pads alone and they were back to normal within 3-4 stops.

    100% confirmed as a Shimano finned metallic pad problem. The good news is there's a quick fix, the crappy part is you need to do it all the time. I'll see if I can get in contact with the local Shimano reps and see what they say.

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    Quote Originally Posted by BuickGN View Post
    Once again, instead of trying to say I'm wrong with facts or at least a factual based argument you get all emotional. You made a statement of "Wow lots of problems with Shimanos......". Not lots of problems. The same problem in almost every case which would be a problem with the pads, not the brakes themselves. You're so quick to make a blanket statement as if Shimanos have tons of problems. Leave your emotion and bias out of it and we can have a conversation. A bad batch of pads does not compare to all of the Avid brake failures that occurred over the past 10 years. I can't believe you would even go there. The Guides hopefully will prove to be reliable but only time will tell. It's been long enough that I'm going to finally pull the trigger on a set but I'm still a little leery of going with Avids again.

    I can't admit problems with my brakes? I've stated every problem. The metal pads squealed and had no power but when I dug deeper I found that they were bent. What's the problem? I don't think we can blame Shimano and we definitely can't blame the brakes.

    My Zees weren't bled properly when I got them so I bled them and they've been trouble free ever since, almost a year now.

    I've been very vocal about the pads that corrode when sitting and lose power until I've ridden several miles.

    I've inquired about the aluminum sandwich rotors melting and started looking into other brands' stainless 2 piece 220mm rotors. After the recent descents, I've realized that I can't get my rotors to melt if I try so I'm sticking with what's on the bike but I was about to jump ship until I dug deeper.

    I'm sure I will be called a jerk for stating that I don't hate Shimanos lol.

    To you, an insult is presenting facts that go against your beliefs so I'm not too worried about those accusations. You have at least 2 threads right now unprovoked throwing out insults to "Shimano Fanboys" and something about dying a slow death that myself nor other Shimano owners have posted in. They're just a chunk of metal, I don't have some undying loyalty to them as you seem to have.

    I don't care if you have opinions no matter how wrong they might be but you state them as facts and that's where the problem is. I've given the Guides several good reviews, I'm getting ready to use them on my XC bike as I've stated numerous times but I can't admit that Avid has good products? Get over yourself. You've created this little battle of Avid vs Shimano. I've always kept my posts factually based and when I have an opinion I state it as an opinion and I usually explain how I arrived at that opinion or conclusion so others might be able to tell me if I'm right or wrong.

    You on the other hand love to keep everything subjective and you flip out when there's a fair objective apples to apples comparison and your brake doesn't come out on top. I'm not the one comparing one brand's power with 160mm rotors to another brand's power with 203mm rotors. The different sized rotors were not brought up by you, luckily another poster was sharp enough to remember what you were running. You were going to compare the two brakes with drastically different sized rotors and not tell anyone!?!? Maybe a little bias here? Once called out you state that it's fair because the bike with the XTRs is 6 lbs lighter so it evens out!!! Wow. I hope you realize now that, that was an opinion and a severely misguided one. If you had done even a tiny bit of research you would have seen that 6lbs makes no difference compared to the rotor size difference but I don't think accuracy is what you're after....

    After getting called on it and after the pads are bedded in, you say the XTRs are nice but you make no mention of power. You say you can't compare because the bike with the Guides is ridden under different conditions. Different conditions might test out the heat dissipation but all you need is to do a couple stops in your driveway to know which brake requires less effort for a given deceleration rate. It seems like you're purposely trying not to compare the power of the two. Remember, initially you exclaimed that the Guides are way more powerful and anyone who says they're not more powerful has never tried them or has tried both brakes. Once the XTRs are bedded in, you have no opinion of which one is more powerful all of a sudden because of different conditions but the conditions didn't stop you from that opinion at first when the Guides were stronger.

    I would never compare brakes with different sized rotors and pads not bedded in, at least not without making it very clear in the comparison. I'm not the one saying 4 piston brakes are stronger than 2 piston brakes and the list goes on and on. You state your opinion as fact and get pissed off when you're proven wrong by actual facts and start calling us jerks. I enjoy learning so if someone proves me wrong it's fine, it means I learned something new. My entire worth as a human being is not centered around whether or not my brakes are the best in the world or whether I'm always right lol.

    It's easy to see what's going on, you seem to have trouble telling the whole truth and you get very defensive when called on it no matter how nicely it's done. My stance between the two brakes has always been that power is so close that power should be the last thing anyone looks at when trying to decide between the two. I've said several times that I can see how some would like the lever throw and feel of the Guides better. There are subjective items, personal preferences which can sway a person either way but which brake has the most power on a level playing field is not subjective, the Shimano 2 pistons do have more power but it's so slight it probably won't matter to most. Who's the fanboy here?

    I'm sure your reply is going to be more of the same. I'm a fanboy and I'm a jerk followed by some emotional knee jerk reaction with no facts to back it up and you will ignore everything said above.
    Same as always, you take a portion of what I have said and twist it, days later and paragraphs later.

    I said that they were not bedded to qualify my initial impression and twice later stated guides as more powerful, in my opinion.

    I mentioned the bike weight difference and load difference, you clinged to the bike weight only. Load was about initial response, not fade.

    Shimanos have threads about squealing, pad issues (multiple), leaking. Not just one issue.

    You do not mention I love my new XTRs and I am looking to get Saints. So, your argument about this being Shimano versus SRAM holds no water.

    Glad I was able to get you to understand Guides are worth a look, you are welcome!

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    Once I switched to third party pads the problem went away. While I hated the squealing what really drove me crazy was the fade.
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    So when the pads were new I would ride once a week with no fade. Then all the sudden, after winter, they fade overnight. I wonder if absorbing moisture is the culprit. If that's the case, like others seem to have done, some time in the oven or a good hot downhill run should fix them for longer than a day.

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    Quote Originally Posted by aerius View Post
    And it's confirmed, sanding is only a temporary fix and will be required before each ride if the brake pads have gone unused for a while. I rode the same pads today which I fixed via sanding a couple days and they're back to squealing with no power. Did another quick sanding on the pads alone and they were back to normal within 3-4 stops.

    100% confirmed as a Shimano finned metallic pad problem. The good news is there's a quick fix, the crappy part is you need to do it all the time. I'll see if I can get in contact with the local Shimano reps and see what they say.
    I bought a set of Galfer pads for my wife's set of XT 785 brakes. They'll be here next week and I intend to clean the rotors and bed them in, and see how it works with her usual ~2 rides a week.

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    This thread s fascinating. Thank you everyone for the info. I have struggled greatly with my brakes over the past few weeks. Long story short, upgraded to 2014 XTs last year and loved them. Winter in the northeast US this year meant the bike was stored in my basement for about two months. I took it out and I had zero braking power and the noisiest of brakes. I actually crashed rolling down a hill to the trails as I need to speed check and couldn't. The brakes are so consistently noisy that I am a joke at the trails as I can tap my brake levers as if they are musical instruments. I'm well versed in servicing bikes and I have tried everything short of replacing the pads. I've known it was a pad issue but I didn't want to buy new ones if this would happen again. I think I'll continue to sand them for now.

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    I found this thread because I have the same problem with my Shimano XT 785's. I rode in Moab after sitting throught he winter and my brakes were fine. I put the bike away for 2 months while having the fork serviced, and just took it out yesterday.

    I found that the rear brake was squealing initially, but then this squeal went away. I started the ride and found that I had NO power at all in my rear brake, but had full power in the front. I would pull the rear lever hard and there was no stopping power, and I could not make the bike skid. I will try taking the blowtorch to the pads, cleaning the rotor with rubbing alcohol, and see if I can get this working...

  109. #109
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    So I called Shimano and of course: "It's probably cooked rotors. It's probably contaminants from cleaners or grease. It's probably a leak. Blah blah blah." But I did get the name of a higher up in the organization with an email address, and I'll send an email and follow up.
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    try put the pads on a stove, make them hot enough to see a bit of smoke, then let them cool off.

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    Quote Originally Posted by eicca View Post
    So I called Shimano and of course: "It's probably cooked rotors. It's probably contaminants from cleaners or grease. It's probably a leak. Blah blah blah." But I did get the name of a higher up in the organization with an email address, and I'll send an email and follow up.
    I'm not surprised. I wonder if they would change their tune if they read this thread?

    My rotors are what I would call cooked. They're blued and even the non braking track is discolored all the way to the aluminum hub/spider. They still work great with resin pads which are the same pads that were on there when I got the rotors really hot. They probably get lots of calls from people that don't know any better that really do have one of the problems mentioned but this seems wide spread enough that they need to listen to the problem they're having with their pads.
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  112. #112
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    I bought a brand new bike this year equipped with XTR trail brakes. On first use, the fronts bedded in nicely but the rear lacked power and squeaked. The rear rotor also discolored after an hour of riding. After a lot of reading, I decided to sand the pads and rotor and gave the entire system a cleaning with brake cleaner. After bedding in the rear, it felt as good as the front. 3 weeks of riding went by with no problems. In the 4th week, I felt a drastic loss of power in the rear with some squeaking and rotor glazing. Although I could not see any leaks, I suspected a leak somewhere.

    After repeating the cleaning and daily monitoring, I discovered there was a very very small leak in the hydraulic hose where the banjo fixing is crimped to the hose. Closeup, I could see the shimmer of fluid where it should have been dry and dusty. I contacted Shimano and they gave me a new hose, new pads and fitted it under warranty. *Touch wood*, it won’t come back.

    According to my LBS, many hoses were crimped poorly resulting in undetectble leaks. It would not surprise me if some of you have such a small leak it takes 2 months to contaminate your brakes. Mine took 3 weeks whether I was riding or not.

    Regarding resin pads themselves, I’ve gone through a couple of sets since the leak was fixed. At no time did they glaze in use or out of use and they required no maintenance such as sanding or cleaning. I am pretty sure a leak is the primary cause of glazing.

  113. #113
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    Quote Originally Posted by c8stom View Post
    I am pretty sure a leak is the primary cause of glazing.
    Been over this already and it's definitely not.
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  114. #114
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    ^^ Yep, numerous folks in this thread have no leaks and yet still have the issue.


    I got the Galfer pads for my wife's bike on Tuesday but I'm about to head out of town for the holiday weekend, so it'll be towards the end of the month before I can report on them.

  115. #115
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    Sent Shimano a detailed email and received a call from a service supervisor yesterday. I sent him this thread and a few others plus my pictures and experiences and he agrees, something is going on. He said that while microscopic leaks can sometimes go undetected and cause similar symptoms, sanding would never recover the pads. So he's sending me a few pairs to do tests on.

    I also had an epiphany. I think humidity may be the cause. When my M775s and M395s had the issue, it took a week or two for the pads to degrade, and only a mile or so to revive them and they didn't give me any more trouble. Those two brake sets sat in a shed when not used where the ventilation is pretty constant, and outside humidity is always fairly low. Utah is of course a dry state.

    My M596s, on the other hand, gave me no trouble until after sitting in my college apartment for over three months. That apartment has no central ventilation, is practically sealed tight, and showering and cooking in a small space like that produces high humidity. Now those brakes can't even make it a single day of rest without fading. Sanding brings them back, like I mentioned, but I believe it's entirely possible the pads absorbed a ton of moisture and now whenever fresh pad is exposed it oxidizes much faster. If this is true, and the chemical change is because of moisture in the pad meeting air, putting them in the oven for ten or twenty minutes should burn the water out and put a stop to the problem. When I get my new pads I'll give it a try and report back.

  116. #116
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    For what its worth, I use the below on my bikes
    SHIMANO G01A Resin Disc Brake Pad - Y8J79803A
    SHIMANO GO3Ti Metal Disc Brake Pad - Y8J79804A

    On the purchase of my bike, my buddy threw in a few free sets of the resin and metallic pads, some packaged and some loose. I stored them all loose in a non-air tight plastic parts box along with other bike bits. After 4 months and 7 months, I put on new pads with no issues. They bedded in and have been quiet since so i don't think the above pad compounds change unless they are sprayed with some sort of sealant before coming out of the factory. Note where I live the humidity ranges from 75 to 100%.

    In the case of your pads, sounds like something going on.

    Whatever the cause is, hope you get to the bottom of it.
    Last edited by c8stom; 05-25-2015 at 02:42 AM.

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    Eicca. Thanks for taking the time to reach out to Shimano. Based on my experience I agree that it is some level of oxidation (either in the pads, or on the rotors which is then contaminating the pads when we brake). Please keep the thread updated. As I've ridden this spring I've need to clean my pads and rotors which has quieted things down a bit, though they still squeal under hard braking and I can't get back to full braking power.

  118. #118
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    My moisture theory may have just died. I rode to work in the rain, 4 miles with very little braking, and suddenly they're good as new. I could barely stop when I left the garage. Maybe the water cut through the glaze somehow.

    I'm beyond perplexed now. I'm going to take them out at let them sit and watch them for a few days.

    In fact if anyone is currently still dealing with the issue, see if pouring water all over the caliper and then riding makes any difference. Take a bottle with you and douse it frequently.

  119. #119
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    I have ridden in the rain plenty of times. It's not moisture, but if they sit for a while, something changes. I think it's an organic growth of a fungus or slime or algae. It gets cooked off with use. I have not had to sand my brakes, just use them and they come back to life. But if I use my bike more than a couple of times a week, it doesn't happen.
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  120. #120
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    Quote Originally Posted by eicca View Post
    My moisture theory may have just died. I rode to work in the rain, 4 miles with very little braking, and suddenly they're good as new. I could barely stop when I left the garage. Maybe the water cut through the glaze somehow.

    I'm beyond perplexed now. I'm going to take them out at let them sit and watch them for a few days.

    In fact if anyone is currently still dealing with the issue, see if pouring water all over the caliper and then riding makes any difference. Take a bottle with you and douse it frequently.
    I'll definitely try that next time I go out which might be this afternoon.
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    I have had the same issues as well, if my bike goes unused for more than 2 days I get horrible squealing and no power. All I have to do to get power back is drag them lightly for 5-8 50m runs, then put water over calipers and a further 3-5 high speed stops, I have used original pads, and nuke proof (sintered & organic). I never sanded pads/rotors, and not cleaned rotors, again can't see any sort or leak, and every thing looks dry after left standing for a while.
    It's really a strange phenomenon defiantly not ideal, and a PITA, but once sorted I have no issues, and am really happy with the performance/feel.
    Unfortunately I have just bust my clavicle badly, surgery to follow, so I guess I will be following my above procedure when I get back on bike in 4-6 weeks. Will keep following this, hopefully some one has a eureka moment and let's every one know!!!

  122. #122
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    Quote Originally Posted by will 6.6 View Post
    I have had the same issues as well, if my bike goes unused for more than 2 days I get horrible squealing and no power. All I have to do to get power back is drag them lightly for 5-8 50m runs, then put water over calipers and a further 3-5 high speed stops, I have used original pads, and nuke proof (sintered & organic). I never sanded pads/rotors, and not cleaned rotors, again can't see any sort or leak, and every thing looks dry after left standing for a while.
    It's really a strange phenomenon defiantly not ideal, and a PITA, but once sorted I have no issues, and am really happy with the performance/feel.
    Unfortunately I have just bust my clavicle badly, surgery to follow, so I guess I will be following my above procedure when I get back on bike in 4-6 weeks. Will keep following this, hopefully some one has a eureka moment and let's every one know!!!
    I think you're the first to have this problem with aftermarket pads, at least that I can remember. Are you absolutely sure there's no fluid leakage and do both brakes have the same problem?

    Do you have Icetech rotors?
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    Running icetech rotors and same issue on both front/rear, I was out in Cyprus for a while v dusty so any minor leak would show up? A few times I have given a calipers a v good clean, stripped down, cotton buds out, then left for afew days no sign at all of leakage, but squeal/loss of power still occurred. Plus I have never sanded/baked/cleaned pads to get power back, just do the above mentioned ritual, wouldn't contamination require that or replacement pads. In UK now, and loss of power happens in a shorter period of time, I think.
    Once I get them "burned in" they are back to original power, and I am v happy with performance.
    I am going to keep a better tab on what I do, I think that after I have used v aggressive they go off quicker than after a lighter use. Might also swap over spare hope rotor, and see if that makes any difference

  124. #124
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    Last time I fixed them by sanding. This time I tried just cooking them by braking hard, and it worked.

    I used a section of road with a steep hill, got momentum then braked hard. Repeated 4 times and fixed.
    Last edited by matto6; 06-06-2015 at 09:27 PM.

  125. #125
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    Hi,

    Out of curiosity, I have been following this thread, because I have XT brakes and never had this problem, or at least I never noticed this problem.
    I have XT brakes with finned metallic pads. My front rotor is an IceTech SM-RT86 203mm and my rear rotor is a standard SM-RT56 180mm. My winter season is very rainy and muddy and my summer season is dry and dusty.
    I ride in rainy days, cold days, foggy days or all the above at once. Some times I leave my bike in the garage without washing it first and my calipers stay wet and covered in mud until the next ride, that could be in the next day or 5 weeks later.
    My garage is underground, meaning it is always cold and in the winter can be a little humid.
    As I said before, I never had this problem, so if you want to ask anything about my brakes to compare with yours, just ask.

  126. #126
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    May I suggest someone who has this problem try the following ; before you park the bike for a few days or weeks, remove both sets of pads and place one set near the bike but exposed. Place the other set in an air tight container. The next time you ride, inspect the rotors for anything unusual and clean if necessary. Then put both sets of pads back on and let us know if they squeal.

  127. #127
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    ^^^ No one should have to do this.
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    I think he is suggesting it for the sake of identifying the problem, not proposing it as a solution..

  129. #129
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    Quote Originally Posted by Aglo View Post
    Hi,

    Out of curiosity, I have been following this thread, because I have XT brakes and never had this problem, or at least I never noticed this problem.
    I have XT brakes with finned metallic pads. My front rotor is an IceTech SM-RT86 203mm and my rear rotor is a standard SM-RT56 180mm. My winter season is very rainy and muddy and my summer season is dry and dusty.
    I ride in rainy days, cold days, foggy days or all the above at once. Some times I leave my bike in the garage without washing it first and my calipers stay wet and covered in mud until the next ride, that could be in the next day or 5 weeks later.
    My garage is underground, meaning it is always cold and in the winter can be a little humid.
    As I said before, I never had this problem, so if you want to ask anything about my brakes to compare with yours, just ask.
    I think this is the most telling post here. It eliminates environmental factors and rotor type. I was really beginning to think the stainless/aluminum sandwich combined with the metals in the pads were having some kind of reaction.

    I truly think it's an issue with pads only. Maybe environmental factors can speed up the process but then again I only had under 24hrs till mine lost all power and I live in a dry area and keep the bike inside.

    The only question I have is have your pads ever gotten good and hot? That seems to be what started the problems with both sets of mine.
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  130. #130
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    Quote Originally Posted by c8stom View Post
    May I suggest someone who has this problem try the following ; before you park the bike for a few days or weeks, remove both sets of pads and place one set near the bike but exposed. Place the other set in an air tight container. The next time you ride, inspect the rotors for anything unusual and clean if necessary. Then put both sets of pads back on and let us know if they squeal.
    Quote Originally Posted by Cleared2land View Post
    ^^^ No one should have to do this.
    Quote Originally Posted by newtrout View Post
    I think he is suggesting it for the sake of identifying the problem, not proposing it as a solution..
    That's correct...that's how I indentured it.

    To restate my meaning...it's ashamed that we have to go through this to identify a problem.
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  131. #131
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    Quote Originally Posted by Cleared2land View Post
    That's correct...that's how I indentured it.

    To restate my meaning...it's ashamed that we have to go through this to identify a problem.
    I agree but it looks like Shimano might try chalking it up to dumb consumers over looking obvious problems and not their pads. Hopefully they realize there's a legit problem with their pads that's not caused by contamination or environmental factors.

    In the beginning my problem wasn't bad enough to complain about. Most sintered pads don't grab too well until they have a small amount of heat into them, usually during the first stop they come up to full power. My Trance is used for everything including a ride around the neighborhood or at the park with the fiancée and the dog. The brakes got so bad that they would never get to even acceptable power to the point I almost ran over my dog when he walked in front of me. I ended up putting my feet down to stop because that was much more effective than the brakes were. Then the problem eventually started on my new XTs on the Epic which also now has resin pads with great results.
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  132. #132
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    Quote Originally Posted by BuickGN View Post
    (...)
    The only question I have is have your pads ever gotten good and hot? That seems to be what started the problems with both sets of mine.
    In some long and steep descents on fire roads with loose gravel, I have to drag the front brake. So they get really hot, but I never blued a rotor. Neither Icetech nor normal.

  133. #133
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    Quote Originally Posted by BuickGN View Post
    I agree but it looks like Shimano might try chalking it up to dumb consumers over looking obvious problems and not their pads. Hopefully they realize there's a legit problem with their pads that's not caused by contamination or environmental factors.
    We just need one person with the issue to scrape some convincing evidence together and to bring it to Shimano’s attention. In my experience, Shimano ( Asia ) has always been responsive and reasonable when presented with decent evidence.

    That said, I think it will be near impossible to prove a given set of Shimano pads are defective without performing tests on a few identical sets in controlled conditions. Sadly, the onus falls on the poor consumer as Shimano are well aware there are thousands/millions of pads out there that do not have these issues.

    I believe one user in this thread has already contacted Shimano but I am not sure if there was a response ?.

    When my defective banjo on my new bike leaked and contaminated my pads, I was also given new pads along with cables by Shimano because my LBS confirmed my pads were damaged as a result of the defective banjo. If my LBS did not confirm this, I would have only received replacement cables under warranty and would have had to fork out for a new set of pads despite the bike being new. It appears Shimano’s policy on replacement pads is extremely strict / brutal.

    I suggest those affected try contacting Shimano as they may respond favourably. Afterall, pads are cheap and will not dent the balance sheet if they have give out a few hundred sets for free... Goodluck

  134. #134
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    I started this thread, and still experience this problem on occasion. I also use a few truckerco pads, which are NOT immune to this problem. I've changed rotors, avid, shimano pre-icetech, and ictech rotors... Still happens occasionally when a bike sits idle for 6-8 weeks.

  135. #135
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    Perhaps the best fix is to NOT sit idle.

    Get on your bike and ride.
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  136. #136
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    Quote Originally Posted by rfxc View Post
    I started this thread, and still experience this problem on occasion. I also use a few truckerco pads, which are NOT immune to this problem. I've changed rotors, avid, shimano pre-icetech, and ictech rotors... Still happens occasionally when a bike sits idle for 6-8 weeks.
    Have you changed the caliper at all ?

  137. #137
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    I took off the pairs that are giving me trouble, labeled them, sanded them, and I'm letting them sit inside the Shimano plastic packaging that pads come in. If experiences hold true, I should see the gold surface fade to that grey glaze in a few days. I'm taking pictures of every step.

    Meanwhile, I installed the metallic pads Shimano sent me and went on a good ride aside from my usual work commute. 1) They modulate and stop waaaaay better than the resins and 2) they haven't given me any idle-fading trouble. Yet.

  138. #138
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    Quote Originally Posted by eicca View Post
    I took off the pairs that are giving me trouble, labeled them, sanded them, and I'm letting them sit inside the Shimano plastic packaging that pads come in. If experiences hold true, I should see the gold surface fade to that grey glaze in a few days. I'm taking pictures of every step.

    Meanwhile, I installed the metallic pads Shimano sent me and went on a good ride aside from my usual work commute. 1) They modulate and stop waaaaay better than the resins and 2) they haven't given me any idle-fading trouble. Yet.
    Good stuff.... Does the gold surface contain brass ? I believe brass is quite stable so it must be something else causing the fading. Post some pics later and happy braking the meantime

  139. #139
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    Quote Originally Posted by eicca View Post
    I took off the pairs that are giving me trouble, labeled them, sanded them, and I'm letting them sit inside the Shimano plastic packaging that pads come in. If experiences hold true, I should see the gold surface fade to that grey glaze in a few days. I'm taking pictures of every step.
    Interesting experiment! I had wondered if it's not only the pad, but proximity to the stainless steel rotor. Bi-metallic corrosion, perhaps.

  140. #140
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    I have resin pads on my 2014 XT brakes and they have howled since day one. Sanding the pads and even the rotors did nothing, rubbing alcohol and degreaser were fruitless as well. Eventually the pads got quieter as I rode through the summer but the sound never fully went away.

    Started riding again this spring and the sound was way worse. I then hit the pads with a propane torch for about 30secs each causing them to briefly catch on fire (1-2secs). Since then my brakes have been silent with better power.

  141. #141
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    Quote Originally Posted by oweya View Post
    I have resin pads on my 2014 XT brakes and they have howled since day one. Sanding the pads and even the rotors did nothing, rubbing alcohol and degreaser were fruitless as well. Eventually the pads got quieter as I rode through the summer but the sound never fully went away.

    Started riding again this spring and the sound was way worse. I then hit the pads with a propane torch for about 30secs each causing them to briefly catch on fire (1-2secs). Since then my brakes have been silent with better power.
    That sounds like fluid contamination.
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  142. #142
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    Wife's bike with XT M-785 brakes is working extremely well with Galfer FD452 pads. She does not have any leaks - if you do, obviously that needs to be resolved first, because any leaking at the caliper will ruin any pad.

    I got them here: Galfer 1053 Standard Shimano Brake Pads > Components > Drivetrain, Brakes and Pedals > Brake Pads | Jenson USA

    Installed pads, verified rotor clearance, cleaned both rotors with a lint-free rag and rubbing alcohol. Then I bedded in both brakes. Tons of power and no noise. They've been fine for over a week so far but I'm not willing to call it 100% good just yet. I'd like to get a month down the road to be sure.

  143. #143
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    Interesting story regarding this issue. At my LBS shooting the sh!t w/ a local rider who has/had a LOT of bikes. He has had nothing but problems with Shimano brakes, and owns many different brands (so I assume he is not a ham fisted dork). His issues mirror what many others have said in this thread EXACTLY.

    I commented that I have not had any issue with my cheapy deore brakes and Ice Tech rotors. WELL, WOULDN'T YOU KNOW ON THE VERY NEXT F'IN RIDE my rear brake started acting up. Pull the lever, next to no power (friction), then when the power does come on (maybe 50%) they let out a AVID BANSHEE scream!!

    Looks like it is time for a pad sanding fest, then onto maybe some new pads or Hopes.

  144. #144
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    I had both Deore and XT squeal until I baked them for 1 hour at 350 degrees. My calipers had not leaks so it was something with resin pads that was causing it. After baking, brakes were great. I will have to bake them at the beginning of each season but at least I know the reason for it.

    Quote Originally Posted by jonshonda View Post
    Interesting story regarding this issue. At my LBS shooting the sh!t w/ a local rider who has/had a LOT of bikes. He has had nothing but problems with Shimano brakes, and owns many different brands (so I assume he is not a ham fisted dork). His issues mirror what many others have said in this thread EXACTLY.

    I commented that I have not had any issue with my cheapy deore brakes and Ice Tech rotors. WELL, WOULDN'T YOU KNOW ON THE VERY NEXT F'IN RIDE my rear brake started acting up. Pull the lever, next to no power (friction), then when the power does come on (maybe 50%) they let out a AVID BANSHEE scream!!

    Looks like it is time for a pad sanding fest, then onto maybe some new pads or Hopes.

  145. #145
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    Quote Originally Posted by jonshonda View Post
    Interesting story regarding this issue. At my LBS shooting the sh!t w/ a local rider who has/had a LOT of bikes. He has had nothing but problems with Shimano brakes, and owns many different brands (so I assume he is not a ham fisted dork). His issues mirror what many others have said in this thread EXACTLY.

    I commented that I have not had any issue with my cheapy deore brakes and Ice Tech rotors. WELL, WOULDN'T YOU KNOW ON THE VERY NEXT F'IN RIDE my rear brake started acting up. Pull the lever, next to no power (friction), then when the power does come on (maybe 50%) they let out a AVID BANSHEE scream!!

    Looks like it is time for a pad sanding fest, then onto maybe some new pads or Hopes.
    Stay cool man. Rip those pads out, douse them in any flammable liquid of your choice and set them on fire. Then call shimano and give them an earful. By the time you're done on the phone, pads will be ready to go back into the calipers if they've not completely incinerated. You should then feel better, perhaps.

  146. #146
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    ^Haha!

    I went for a pretty hard ride last night and the rear brakes came back to life w/o the need for FIRE!! I will follow up if I continue to have issues.

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    I installed a new set of Shimano Zee brakes on my Slash in Feb this year after my Avid Elixir 5's suddenly gave up (again). I retained my Avid 200mm rotors as I'd just replaced them.

    Not had any issues at all for the last 4 months - Great power, modulation until I left my bike for 3 weeks without riding it this month (I was riding another for my commute).

    I tried the bike last night as I felt like a quick trail blast - no brake power, squealing and very bad modulation.

    It has sat in my basement in a controlled temp environment, without sunlight etc so have no clue what has caused this.
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    Same issue here. I've read the hole thread with hope, but no real fix yet. This is driving me crazy. My problem is exactly as described here: terrible squealing and power loss after sitting the bike for a few days. M785 brakes with RT81 IceTech rotors and finned F01A resin pads (although same issue happened with F03C metal pads). Just to add some more intrigue, it is only happening with my rear brake, front brake works great with the same components. I tried everything, replacing rotors, pads, cleaning, bleeding, sanding everything, etc. I cannot see any leaking, so unless it is microscopic, there is no reasonable explanation for this.

    I can't believe the pads just get glazed magically just by doing nothing. Although I store the bike in a terrace partially outdoor close to the sea (humidity and salty air) I discarded the environmental theory as my front brake works like a charm. There must be something else....



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    So I am in the boat as well with my 2014 XT brakes and my wifes 2014 SLX brakes. Pads are shot if left sitting for longer than 2 months. First time the shop blamed it on me that I contaminated the pads somehow. So I sprung for new pads for both bikes.

    Next time my bike did it, once again shop said it was me or the brakes have a leak, once again I put new pads on it. I went thru the system thoroughly and there were no leaks at all, I wiped the entire caliper down with brake cleaner from top to bottom. Put new pads in and got 3 rides on them before I parked the bike. We don't do much summer riding here in Oklahoma, not much of any trail maintenance and the trails get over grown with poison ivy and ticks.

    Pulled the bike down 2 weeks ago and once again pad squeal and no power. I had some parts in the over so I went to test moisture contamination theory. Baked the pads at 300° for two hours. Then removed them and lightly sanded the glazing off. Re-bedded the pads and back to normal. All of these sets of pads have been resin.

    Called Shimano, the tech said it is an issue with resin pads. Said take it to the dealer since the XT stuff is under 2 year warranty. Took it to my LBS, Shimano tech told them he had never heard of moisture contamination. He ran the mechanic thru all sorts of tests and check, finally came back and said it is an issue with the caliper that Shimano knows about. Said it is leaking slightly causing the issue. They are sending me new calipers and pads for both ends.

    Now the sad part to the story, another mechanic told me he has 2 customers going thru the same thing, but system is out of warranty. Shimano told him the same thing, bad calipers. Now here is the crappy part, if you are out of warranty Shimano does not offer a parts rebuild kit nor do they offer the caliper by itself. Only option was to buy a whole new system.

    So if you are under warranty Shimano will take care of it, if you are not then you get to pound sand. So one of my bikes is covered and I have to eat an entire system on my wifes bike or else replace the pads again.

    Also you want to know what Shimano's suggestion is to stop the issue, remove the pads when the bike is not in use and store them in a plastic baggy.

    Nice Shimano, real nice....
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  150. #150
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    I think SRAM Guides will be my next brake purchase.

    TJay74, did baking the resin pads prevent them from losing power when sitting? I was going to try that with my set I have sitting around.
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    on the short test rides in my neighborhood it seemed to have corrected the issue. Power came back and no squealing at all.
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    And now it gets interesting. Friend of mine bought a set of Saint brakes (H03C pads) which had the same power loss issue as the ones I have, his pads were going bad on him overnight. He was dealing with it the same way I was, sand them before each weekend trip to the local the bike park. Recently, he went on a trip to Mont Saint Anne for a week and did a ton of runs on the world cup course and other DH trails. After a few days of riding there, his brakes were cured and he didn't need to sand them anymore. It seems the long DH runs and heavy braking put enough heat into the pads to bake them in and fix them, and a week later they remain fixed.

    So I gave my own H03C pads a quick sanding, put them in the toaster oven and baked them at 450F for 15 minutes, then left them in there for a half hour or so to cool down. I did a short ride to bed them back in and then let them sit for a couple days, which was enough to make them go bad in the past. This time, they stayed working. Full power, no noise, good as new. Hopefully, this is a permanent fix, but to be sure I'll have to pull the pads and let them sit for a couple weeks. We'll see what happens next month, but fingers crossed, it looks like there's a cure for the finned metallic pads.

  153. #153
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    This is crazy. I tried with a different set of pads, Shimano Aluminium G01A (Resin) a few days ago. I just sand them a bit along with the IceTech disc just to remove any contaminated residue and sit the bike in the terrace covered with its BikeParka. Today guess what .... same noise again. I didn't even ride the bike. Who the hell can explain what is happening? Everything points out to some kind of micro-leaking (whatever pads you put there, they got ruined). However, if that is the real issue, I should see something by inspection or I should notice a change in the brake lever pressure (leading me to add some oil to the system from time to time). But this is not the case.

    I decided today to cook my pads, it's worth a try. I used a lighter and let them on fire a couple of minutes intermittently. After sanding them a bit, the surface looked best than ever and its typical gray color with traces of golden/copper metal came to life. A few rides in the street and the brake works better than new, with full power and a lot of bite. Lets see if that remains much more of a mirage than a real fix ...

  154. #154
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    The baking process definitely works for the Shimano metallic pads. Did it with my Saint H03C pads. Basically had to since they got contaminated with mineral oil from a messy bleed.

    Baked them @ 400F for about 1 hr. Sanded them first. Also cleaned the rotors with brake kleen. Reassembled and proceeded to bed them in. After a few stops - as good if not better than new!! Definitely worth a try especially if your pads have lots of life left in them.

    My bike sits often for 1-2 weeks at a time without riding. Never had the "power loss" issue. But in a high moisture environment, with metallic pads, I could see that happening. Baking seems to work!

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    And an update. I believe there's now a permanent fix for the finned metallic pads which are suffering from the squeal & power loss issue. The short version is clean them, give them a quick sanding, then bake them in a toaster oven at 450°F for 15-20 minutes and let them cool. I did this to my problem sets of pads about 2 weeks ago, rode them, put them away, and today they are still working properly. Success at last! Before this they'd always go bad again within a couple days.

    The longer version is I've had 2 sets of H03C pads which came with my Zee brakes that for whatever reason lost all power and squealed like mad when I let them sit unused for a couple days. All my other sets of pads worked perfectly fine with no issues whatsoever in the same brakes, so by process of elimination it was confirmed as a pad problem specific to those 2 sets of pads. I tried various other fixes such as cleaning with alcohol, sanding, and so forth, but nothing ever stayed fixed for more than couple days, the squeal and power loss always came back. A quick sanding would bring the power back but once the bike was ridden & put away the problems would return.

    I resigned myself to weekly sanding of the pads before bike park or cottage days, and used my non-finned sets of pads for everyday riding. That was, until my friend's pads which were suffering the same issues as my own fixed themselves while he was on vacation at Mont Sainte Anne, it appears the long DH runs and heavy braking baked his pads in and fixed whatever was wrong with them. So I gave my sets a good hot bake in my toaster oven and they're now fixed as well. And they've stayed fixed for 2 weeks and counting, which is about 10 times longer than all previous fixes.

  156. #156
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    Yeaaaahhh! Success for me as well. It seems that baking process works. I literally burnt my resin pads with a lighter for a couple of mintues. I did it with 2 sets, Shimano F01A and Shimano G01A (aluminium plate, not finned). I can confirm G01A works great with the baking, at least no more issues in about 2 weeks. I had to try with the finned F01A just to confirm this fix is reliable.

  157. #157
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    I desperately need to try this with my own and send the results back to that Shimano rep.
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  158. #158
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    Interesting to see this thread as I was researching potential new brakes... I had this issue with XTR brakes a couple years ago and never resolved it, just replaced with hopes and moved on. Was hoping that someone would have solved this by now. Will be following this... was interested in the new black XT m8000

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    Tired of having the same issues with my brakes. Sanded them down and baked them for 15 min at 425F. Cleaned the rotor with 99% IPA, but ran out of time to bed them in. Will do so today and report in a week or two how things are.

    XT 785 brakes
    F01A Resin finned XT pads
    RT56 rotors 180/160

    Left is before and right after sanding with 60 grit paper.

    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks-img_20151001_184430_zpsuv7f1pat.jpg
    Last edited by kryten; 10-02-2015 at 06:04 PM.
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    I posted a few months back that a I had good results with trying to "rebed" the pads on my Deore brakes (which I imagine come with the cheapest sh!t pads known to man). Well, the results were temporary, and now I am back to a lack of power and lots of noise. Time to dump some dump some denatured alcohol on them and let my torch have its way with them for a while.

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    Deores use the same pads as the rest of Shimanos 2 piston lineup. Rebedding is only temporary. You need to bake them or torch them and then sand them lightly for a few seconds. Those look like fluid contamination. From what I've seen, fluid contamination causes a loss of power along with noise. The overnight issue that we believe is oxidation is just a loss of power with no noise.
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  162. #162
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    Quote Originally Posted by BuickGN View Post
    Deores use the same pads as the rest of Shimanos 2 piston lineup. Rebedding is only temporary. You need to bake them or torch them and then sand them lightly for a few seconds. Those look like fluid contamination. From what I've seen, fluid contamination causes a loss of power along with noise. The overnight issue that we believe is oxidation is just a loss of power with no noise.
    Were you commenting one the latest picture above? I don't have any noises, they just loose power after a few days. I was barely able to lock up my rear wheel last time. Either way, it is done now, they are sanded and baked so will see what happens next.
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  163. #163
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    Glad I stumbled into this thread - I have been having many of the same issues! I'll try some of the ideas here and report back.

    My bikes are stored in a shed, so warm and humid all summer here in SC.

    My SS (XTR trail finned pads) sat for a few weeks while I rode another bike and it immediately had a loud front brake and then lost most of the front braking even though the noise quit (after around 20 medium to hard braking cycles) I'll begin with the bake/sand pads and clean rotor and see how that works. Fingers crossed....
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  164. #164
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    Quote Originally Posted by kryten View Post
    Tired of having the same issues with my brakes. Sanded them down and baked them for 15 min at 425F. Cleaned the rotor with 99% IPA, but ran out of time to bed them in. Will do so today and report in a week or two how things are.

    XT 785 brakes
    F01A Resin finned XT pads
    RT56 rotors 180/160

    Left is before and right after sanding with 60 grit paper.

    Click image for larger version. 

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    So I took my bike out for a 45 min ride and the front brake has decent power and bite and stayed working reliably for the whole ride, rear brake definitely has some issues. I can still lock up my rear wheel, but the whole power/feel is not very confidence inspiring. Half way through my ride, rear brake started squealing and lost even more power and feel so that I could barely lock up my rear wheel. Pretty sure pads are contaminated again and my caliper has a small leak.

    It was dark, so I will inspect caliper/lever for leaks this weekend when I get a chance and will report back. I'm pretty much certain it is not leaking at the lever, so it will be caliper leak.

    I guess I'm looking for something like this:

    https://www.youtube.com/watch?v=CtrNAlYcq9Q

    I'm fairly confident that this is my issue now, and once confirmed, I'm leaning to replacing at least my rear brake for now with Zee instead of getting a new XT caliper. My understanding is Shimano does not offer rebuild kit and these came on a used bike so I have no way of claiming warranty with Shimano.
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  165. #165
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    Both my bike and my wifes bike got new calipers (mine XT with metal pads, her SLXwith resin). I took my bike and bedded in the pads and did 3 rides (maybe 60 miles) and then the bike sat for 2 weeks. My wifes bike got bedded in with maybe a 10 mile ride.

    I pulled both bikes down and both have lost all braking power and squeal horribly. I have sanded and cleaned with alcohol on both. LBS called Shimano last week who wanted to throw more parts, LBS said no and demanded whole new setup. Shimano is sending me new XT M8000 full brake systems, wifes bike goes back in next week after mine is fixed to make the same demands on her bike.

    This is getting out of control, if Shimano knows there are issues they need to do something and ASAP. I can promise if my wife or I get hurt because we cant stop that this thread and all of our service records along with Shimano's warranty process will be the first thing I hand over to a personal injury lawyer.
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  166. #166
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    2016 XT brakes here..the black ones with finned metallic pads. Had them for a couple weeks, no issues. Bike was muddy so I hosed it down at the trailhead and wiped it down last Sunday. Had a loud squeal from the front, but nothing from the back. Bike sat for the week until today...brakes were silent and great again.

    I switched from Elixir 5's so I hope this will be the norm.
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  167. #167
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    It is normal for the brakes to squeal after washing.
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    So the shop got the new XT 8000 brakes installed for me under warranty from Shimano. Just need to find some time to test them out and see how they do.
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  169. #169
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    So I had some time to work on the bike and pulled the pads, soaked them in Alcohol and torched them. Then while they were still hot I sanded them. First ride was much better with no squealing and much better pad grip.

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    My resin pads did this for the first time, only the rear. The bike has sat for 2 weeks now. I got tired of just looking at it so I took it through the neighborhood last night and had virtually no rear brake, just noise. These are Zees with finned resin pads. The front was perfect. I think I found the culprit. I remember catching my Golden Retriever licking the rear rotor about a week ago. I'm betting that's the cause. He's trying to kill me.
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  171. #171
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    Quote Originally Posted by BuickGN View Post
    I think I found the culprit. I remember catching my Golden Retriever licking the rear rotor about a week ago. I'm betting that's the cause. He's trying to kill me.
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  172. #172
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    Got the big squeal from the rear in the last lap of the XC race on Sunday. Finned pads, resin front, sintered rear. No water on the course, just a bit dusty.

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    For those of you with squeaky XT/XTR disc brakes I learned today that heating the pads is a necessary step. I have the resin pads with icetech rotors. I heated the pads with direct flame from a mini butane torch. As I heated the pads I saw small sparks of material burning off-as I heated there was less and less material burning off. I stopped heating once the burn off subsided. I assume the material burning is the contaminant but it did the trick. The brakes also had a lot more power after heating them. Before heating the pads I cleaned the rotors and pads with alcohol and sanded the rotors and pads very thoroughly. After this I still had squeaky brakes and the power was poor. You would think Shimano could explain this issue-this has happened to me for years and I have discarded many a good brake pad.

  174. #174
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    Could this issue be related to IceTech rotors? Leaving material deposits on pads...

    I ask because my metal-pad M8000 front brake with IceTech rotor does not sequel, but it lacks braking GRIP... But the rear metal=pad M8000 with a "resin-only" rotor seems to stop very well.

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  175. #175
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    Quote Originally Posted by Rmplstlskn View Post
    Could this issue be related to IceTech rotors? Leaving material deposits on pads...

    I ask because my metal-pad M8000 front brake with IceTech rotor does not sequel, but it lacks braking GRIP... But the rear metal=pad M8000 with a "resin-only" rotor seems to stop very well.

    Rmpl
    It's definitely pad-only. I've had it happen on "resin-only" rotors and some nice Alligator-brand ones too.
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  176. #176
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    ^^^ I fully agree. It's the pads. I was amazed at how well a propane torch 'cooked' the problem. That five minute fix, worked great.
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    I've had over 6 sets of 985/785 series shimano brakes with this problem, as I described in the OP. Resin pads, metallic pads, finned and not, shimano and truckerco-- all have had the issue I originally described if the bike sits for a long period of time. The SAME pads sit in my commuter bike with TRP spyre mechanical brakes and DO NOT have this issue after sitting. The best theory in this thread is that mineral oil very slowly seeps around the pistons and contaminates pads. When bikes are used very regularly, small amounts of oil burn off quick. When they sit, more oil seeps out and contaminates the pads beyond what my local hills allow me to burn off effectively. So I've gotten accustomed to sanding and burning with a propane torch. :/

    I also have a bike with M9020 brakes now for 6 mos, and have NOT had this issue with them. The caliper is different, and the piston looks different compared to the older 785/985/980 series. The M8000 calipers look different as well (in photos)... and I have to wonder if a different/newer caliper piston/seal design has been deployed to prevent this issue in the newer M9020 and M8000 brakes. I'd like to start selling off my (and my wife's) old 985/785 sets and replace with M8000 brakes... but can anyone confirm or validate this notion?

  178. #178
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    Quote Originally Posted by rfxc View Post
    The best theory in this thread is that mineral oil very slowly seeps around the pistons and contaminates pads. When bikes are used very regularly, small amounts of oil burn off quick. When they sit, more oil seeps out and contaminates the pads beyond what my local hills allow me to burn off effectively.

    ... but can anyone confirm or validate this notion?
    I'm not subscribing to this theory.

    I have experienced the same brake related issues in the past and to better define why I disagree (at least in my case) is that I frequently ride on very talcum like trails that place a fine coat on everything. If you have ever seen a talcum like powder around even the slightest oil leak, it appears very obviously that there's a leak or seepage present. After removing brake pads on multiple occasions, I have never seen even the slightest indication of seepage near caliper pistons, seals or banjo fittings.

    I can't explain what the origin of the problem is, but I don't believe it's seepage of brake fluid.
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  179. #179
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    New question here.

    here's what i experience for m8000, stock resin finned pads, stock hose, bh90-sbm.

    front brake
    1 - no howling even if left idle
    2 - instant stop
    3 - free stroke adjusted all the way in, 20mm lever movement before pad engages

    rear brake
    1 - howls after a week without use but goes away after a few heavy dh braking
    2 - had to apply a little more pull compared to front for instant stop
    3 - free stroke adjusted all the way in, 25mm lever movement before pad engages

    i don't see any leakages of any sort for the rear brake, the hose, and the lever... it remains bone dry all throughout. i inspected it with the pads removed and off the frame.

    1 - any ideas why the rear brake operates differently?
    2 - how much do your levers move with the free stroke screw all the way in?

  180. #180
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    Quote Originally Posted by rfxc View Post
    I've had over 6 sets of 985/785 series shimano brakes with this problem, as I described in the OP. Resin pads, metallic pads, finned and not, shimano and truckerco-- all have had the issue I originally described if the bike sits for a long period of time. The SAME pads sit in my commuter bike with TRP spyre mechanical brakes and DO NOT have this issue after sitting. The best theory in this thread is that mineral oil very slowly seeps around the pistons and contaminates pads. When bikes are used very regularly, small amounts of oil burn off quick. When they sit, more oil seeps out and contaminates the pads beyond what my local hills allow me to burn off effectively. So I've gotten accustomed to sanding and burning with a propane torch. :/
    In your case it's almost certainly a slow leak, and yes, I have seen a few cases of SLX and XT calipers leaking oil from the o-ring area which joins the caliper halves. If the same pads which are going bad in your Shimano brakes are working fine in another set of brakes, then the problem is in the caliper.

    However, in my case and quite a few others, we have pads that go bad and pads which don't go bad, all in the same caliper. In my Zees for instance, I had a set of H03C pads that went bad overnight, an older set of H03C pads that stayed working even if I let it sit for weeks, and a set of D02S pads that also stayed good. Same caliper, same rotors, same everything except the pads. So in my case it's clearly a pad issue.

  181. #181
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    I talked to the Shimano rep over the phone about the exact same thing. He says he thought at first it would be a microscopic oil leak, but if that were true, sanding the pads would not bring them back to life like it did in my case.
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  182. #182
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    Agreed, you can't sand away oil residue.

    I believe that it's some form of oxidation if it can be mechanically removed. But that doesn't explain how torching the pads works either.
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  183. #183
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    Quote Originally Posted by spyghost View Post
    ...1 - any ideas why the rear brake operates differently?...
    The longer hose to the rear brake allows for more expansion than the short front hose causing rear brakes to have a slightly softer feel.

    Assuming no rear brake contamination from the increased amount of crap thrown onto them, it's likely that the front and rear have the same potential to make noise. The rear brake noise may well be a function of the difference between the frame/swingarm harmonics compared to the front fork.

  184. #184
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    Quote Originally Posted by gmcttr View Post
    The longer hose to the rear brake allows for more expansion than the short front hose causing rear brakes to have a slightly softer feel.
    This assumption is entirely negligible and wouldn't be discernible to the rider. The master cylinder is not capable of providing enough pressure to overcome the brake line design expansion limits.
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    Quote Originally Posted by Cleared2land View Post
    Agreed, you can't sand away oil residue.

    I believe that it's some form of oxidation if it can be mechanically removed. But that doesn't explain how torching the pads works either.
    Actually it does, heating the pads changes whatever is oxidizing so that it cannot anymore. The heat likely forces all the oxidation to occur at once. Then, you sand the pad and you don't get anymore oxidation.
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  186. #186
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    I agree with the sentiment that longer brake hoses expand more because every single brake I've ever touched has felt softer in the back, regardless of brand, even after a fresh bleed, etc.
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  187. #187
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    Im not totally convinced by the longer hose, softer feel theory. I got a non-series shimano hydro and it didn't feel like this
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  188. #188
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    Quote Originally Posted by spyghost View Post
    Im not totally convinced by the longer hose, softer feel theory. I got a non-series shimano hydro and it didn't feel like this
    Maybe your front brake was softer than it should.
    Except the hose length everything is equal between front and rear, and unless you are using solid metal lines, the hoses will expand, and the bigger the hoses the more you feel this expansion, and you can add the fluid compression too, but that is negligible compared to the hose expansion.
    Don't forget that the hoses are just a plastics tube, a good and special plastic tube, but a plastic tube nevertheless.

  189. #189
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    From this thread: https://forums.mtbr.com/brake-time/x...l#post11547609

    Looking at this pic in particular:


    There's still a bit of hose showing up between the olive and the barb. I took off mine and noticed that I don't have any 'gaps' between the compressed olive and barb fitting (ie only the silver barb is showing up, no black hose in between)...

    I don't have any fluids leaking from the threads though, but could it be that there's a gap between the lever and the barb fitting that traps air, which is nearly impossible to remove no matter how the lever is positioned? No hose showing between the olive and the barb could mean that the flat sides of the barb and the lever aren't contacting at all...

    if that were the case, can i just cut off the olive and replace it with a new one?

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    Interesting that you are using my photo from a previous thread.

    That is perfectly correct. When the connection nut is being tightened the olive is pushed along the brake hose towards the master cylinder until it reaches the end and begins to crush tight to the brake line (hose). You will always have that minimal amount of black brake line on all lines.

    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks-img_6090.jpg
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    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks

    Quote Originally Posted by Cleared2land View Post
    Interesting that you are using my photo from a previous thread.

    That is perfectly correct. When the connection nut is being tightened the olive is pushed along the brake hose towards the master cylinder until it reaches the end and begins to crush tight to the brake line (hose). You will always have that minimal amount of black brake line on all lines.

    Click image for larger version. 

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    thing is, i don't see any black hose between the barb and the olive that's why i'm thinking that there 'might be' a sort of 'gap' between the surface of the lever internal and the surface of the barb...

    i may have incorrectly tightened the nut with the hose not fully seated against the lever internal... not sure if this is a 'possibility' though... but then, I don't get any leaks from the threads...
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    Quote Originally Posted by spyghost View Post
    thing is, i don't see any black hose between the barb and the olive that's why i'm thinking that there 'might be' a sort of 'gap' between the surface of the lever internal and the surface of the barb...

    i may have incorrectly tightened the nut with the hose not fully seated against the lever internal... not sure if this is a 'possibility' though...
    Yes, you could be correct in stating that you might not have pushed the brake line in far enough before tightening the hose connection nut. After placing the olive on the brake hose and inserting the barbed insert, then push the hose into the master cylinder until the hose stops and has reached it's maximum depth into the master cylinder. Then begin tightening the connecting nut. I believe that when correctly executed, you will see the small part of the brake hose between the crushed olive and the barbed insert.

    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks-img_6096.jpg

    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks-img_6089.jpg

    XT and XTR brakes get squeal/power loss after sitting idle for 6-8 weeks-img_6088.jpg
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  193. #193
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    The micro-leaks around the pistons doesn't make sense... Looking at my finned M8000's, I do not see how mineral oil would defeat gravity and wick its way around the aluminum plate that holds the fins and brake material, and the brake material is on the opposite side of the pistons....

    Sounding more and more like poor materials used in the brake pads, especially the metallic pads... Who knows what is compressed into that pad mixture... Maybe recycled brake material from auto brake manufacturing... Who knows...

    Rmpl

  194. #194
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    Quote Originally Posted by Cleared2land View Post
    Yes, you could be correct in stating that you might not have pushed the brake line in far enough before tightening the hose connection nut. After placing the olive on the brake hose and inserting the barbed insert, then push the hose into the master cylinder until the hose stops and has reached it's maximum depth into the master cylinder. Then begin tightening the connecting nut. I believe that when correctly executed, you will see the small part of the brake hose between the crushed olive and the barbed insert.

    Click image for larger version. 

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    Click image for larger version. 

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    no luck... rear still has greater lever travel...

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    ^^^ Is your Free Stroke Screw all the way in?
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  196. #196
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    Quote Originally Posted by Cleared2land View Post
    ^^^ Is your Free Stroke Screw all the way in?
    yes screwed in all the way both levers
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    You might just need a good bleed. Rear brakes can sometimes be a little more difficult. I have had to remove rear caliper and all tie-wraps to hang the caliper and brake line vertically to free trapped air on a rare occasion.
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  198. #198
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    Quote Originally Posted by Cleared2land View Post
    You might just need a good bleed. Rear brakes can sometimes be a little more difficult. I have had to remove rear caliper and all tie-wraps to hang the caliper and brake line vertically to free trapped air on a rare occasion.
    yep am tempted to do it...

    i'll get back as soon as i've done it...

    stay tuned...

    ... while i hope for the best
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    Also Google "Shimano mini bleed," may help finish off the whole procedure real nice.
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  200. #200
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    Quote Originally Posted by eicca View Post
    Also Google "Shimano mini bleed," may help finish off the whole procedure real nice.
    nope it didn't help. i always do mini bleed (5 min bleed).

    haven't dismantled yet though. need to grab additional fluid from the store today... am living in a different timezone
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