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  1. #1
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    Shimano M785 Help

    Hola!
    My front M785 (XT) brake is offering very little stopping power, and plenty of squealing.

    On my previous ride, they were a little noisy, and I noticed for the first time that they weren't biting nearly as well as they had.

    What can I do to restore that beautiful bite that my metallic pads had when they were new? They have plenty of meat left on them.

    I took it to the shop today, and the tech took the pads out, put them on the grinder for a few moments to scrub off some glazing, gave the rotor and pads a little emery paper rubdown, sprayed the rotor with brake cleaner, and while they did seem a little quieter in the shop, they're still not biting, and seems like light braking power at best in my short ride back to my car a couple of blocks away.

    I should mention that I had previously warranty returned a 785 caliper due to fluid leaking at the caliper end, but that isn't the case this time. It's good and dry.

    Admittedly, the line does need to be bled a bit, but I'd like to know if there's anything else I can do to restore that new pad grab. Dull braking when you want aggressive braking isn't much fun, and the squealing makes me want to do something violent.

    Thanks in advance,

  2. #2
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    Check the banjo fittings. Shimano had a bad batch of hoses that had the banjos crimped on improperly leading to leaks.

  3. #3
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    If the shop just cleaned the rotors then the brakes need to go through the "bedding" process again. It will take a few long stops to get the pad material bedded back into the rotors. Give it a little more time.

    Good luck

  4. #4
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    A small update.. After taking the pads out, cleaning them again, and giving the rotor a good wipedown, I noticed when I was cleaning the caliper that there was a small amount of moisture around the banjo with some crud attached. I wouldn't be surprised if that is brake fluid and it might have contaminated the pads. It's the best I've got.

    After that cleaning, they are still incredibly noisy with little stopping power after 10 start/stops

  5. #5
    @trailgrinder
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    How about a bleed just to make sure that nothing funky is going on inside there so at least you know the loss of power isn't from anything else? I know a bleed has nothing to do with the squeaky noise but maybe that can eliminate the mech side.

  6. #6
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    Funny you should say that.. I've been trying for a lonnnng time to find the bits I need to do a bleed on the 785's. Online, I've only found the kit pieces on Ebay in Estonia and Hong Kong, and I'm a bit nervous about sending money there

    Definitely agree that a bleed isn't a bad thing - especially now that I've found a little leakage.

  7. #7
    @trailgrinder
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    You looking for the bleed kit? Or what exactly are you looking for, grab some shimano mineral oil and a syringe and a small tueb to connect to the bottom and you are good to go.

  8. #8
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    Thanks I'm looking for a syringe and I'd like to get my hands on a bleed block as well. I guess we've all probably squeezed once and /facepalm'ed ourself as you picture those pistons closing in on each other, then groaned as you try to separate them with a screwdriver.

  9. #9
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    Quote Originally Posted by Fyrblade View Post
    Hola!
    My front M785 (XT) brake is offering very little stopping power, and plenty of squealing.

    On my previous ride, they were a little noisy, and I noticed for the first time that they weren't biting nearly as well as they had.

    What can I do to restore that beautiful bite that my metallic pads had when they were new? They have plenty of meat left on them.

    I took it to the shop today, and the tech took the pads out, put them on the grinder for a few moments to scrub off some glazing, gave the rotor and pads a little emery paper rubdown, sprayed the rotor with brake cleaner, and while they did seem a little quieter in the shop, they're still not biting, and seems like light braking power at best in my short ride back to my car a couple of blocks away.

    I should mention that I had previously warranty returned a 785 caliper due to fluid leaking at the caliper end, but that isn't the case this time. It's good and dry.

    Admittedly, the line does need to be bled a bit, but I'd like to know if there's anything else I can do to restore that new pad grab. Dull braking when you want aggressive braking isn't much fun, and the squealing makes me want to do something violent.

    Thanks in advance,
    Mine does the same thing.... squeals like a stuck pig.... Have cleaned pads several times and scuffed rotors... works for a few brake uses but then starts to squeal and lose the biting friction between the pads and rotor. Using the XT Ice rotors with with the XT Ice tech brakes. Checked for leaks none found. I still have a firm lever pull but the rotor just slides on thru. Seems like I loose the braking power at the WRONG time everytime. When I pull the pads everytime they are glazed back over.....

    Oh and never a problem with the rear brake
    Trying to painfully relive some of youthful adventures!!

  10. #10
    J-Flo
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    Quote Originally Posted by .40AET View Post
    If the shop just cleaned the rotors then the brakes need to go through the "bedding" process again. It will take a few long stops to get the pad material bedded back into the rotors. Give it a little more time.

    Good luck
    +1

    For some reason the shops don't tell people this. Yesterday my son got new front pads on his brand new bike (we had the shop do it under warranty; pads should not have failed after only one month and 200 miles), and he thought they were no good. I showed him how to bed them in -- they work fine.

  11. #11
    J-Flo
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    Quote Originally Posted by Fyrblade View Post
    A small update.. After taking the pads out, cleaning them again, and giving the rotor a good wipedown, I noticed when I was cleaning the caliper that there was a small amount of moisture around the banjo with some crud attached. I wouldn't be surprised if that is brake fluid and it might have contaminated the pads. It's the best I've got.

    After that cleaning, they are still incredibly noisy with little stopping power after 10 start/stops
    I went through the same hassle with my brakes, cleaning and sanding only to find no fix. The trouble is, if the pads are contaminated then there is probably no way to save them because oil/grease can get into the pad material, and you can't really tell by looking whether they are spoiled. My only suggestion is to start over again but use new pads this time -- it worked for me!

  12. #12
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    If you're cleaning the rotors, get some brake cleaner from the local autoparts store. It will take all of the oil off of the rotors. I sanded mine too after a thorough cleaning.

    If you see any leaking around the banjo, stop using them and get a new hose. Once the oil gets on the pads the brakes are useless. I took the Shimano hoses off and put Jagwires on so I don't have to worry about the leaks again.

    Good luck

  13. #13
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    i just purchased a set of m785 brakes and am looking for the right bleeder block and am not having any luck finding one online. can anyone point me in the right direction?

  14. #14
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    Sounds redneck'ish, but you simply have to heat up your pads with a torch or toss them in the oven @350 to burn out the contamination. I've done the propane torch trick for a decade and it always brings the pads back to life. Heat um up till they stop smoking. Clean the rotors with ISO alcohol and or sand them.

  15. #15
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    Check the banjo fittings. Shimano had a bad batch of hoses that had the banjos crimped on improperly leading to leaks.

  16. #16
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  17. #17
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    nevermind. they came with the brakes! thanks Shimano

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