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  1. #1
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    Juicy 3s - Zero stopping power at rear

    I just bought a used FSR XC Comp with Juicy 3s front and rear and while the front will lock the wheel in a heartbeat the rear will not slow the bike let alone lock the wheel. If I spin the rear wheel and apply full force to the break lever it will stop the wheel, but only just.

    I'm new to disc brakes in general and I have no idea what the most likely cause of this problem may be. I note that the rear brake resevoir does have a small fluid leak (from the cover joint upon pressure on the lever), could it be something as simple as needing a top-up?

    I haven't tried cleaning the discs with alcohol or sanding pads yet but my sense is while contaminants (oils etc) may degrade performance they surely could cause this kind of a failure - or could they?

    From what the seller told me I don't believe the bike has been used enough for the pads to have worn - say around 20 rides, and nothing to demanding. Any thoughts before I take it into my LBS for a diagnosis?

    Thanks in advance

    David

  2. #2
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    I would fix the leak, top off the system and bleed the rears. Probably wouldn't be a bad idea to check the fluid level and bleed the fronts too just to be safe.

  3. #3
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    If your right lever feels softer than your left, then it's likely all you need is a bleed. If it's firm just no power, you probably have a pad contamination issue. Also what the seller says isn't really that reliable not to say that he lied. People tend to bend the truth a little or to me, a lot. If you've heard of JRA, it stands for "just riding along." It's used by many people to describe what they're doing when a wheel collapsed from under them, a frame snapped in half etc. Turned out their JRA means jumping off a house.

    Anyways, it seems you haven't really tried anything yet. Don't give up and take it to LBS so fast.

  4. #4
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    Thanks guys. "Haven't tried anything yet..." correct! I'll remember JRA and I agree completely that I can't rely on what the seller told me, but it just seems strange that the front feels powerful enough to stop a Hummer dead and there simply nothing at the back...unless the guy never used the front.

    Both levers feel feel the same and I assume there'd be a noticeable difference if the fluid was low. Anyway as you guys say, try some things out and see if they fix the problem. Anyone know of a good online guide for 'servicing' these types of brakes? I've heard the horror story about closing them without a disc between them and I don't want to make a similar type of newbee mistake.

    David

  5. #5
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    If your fluid was low enough, it would introduce air into the system causing the lever to feel mushy/spongy whatever you want to call it. You can take the pads out and look at them to make sure their not gone - there should be ~2mm of friction material. It's no big deal if you pump the brake w/o rotor in - you just have to pry it our carefully again.

    In your case, I would do all I can to clean the pads first - soak it in alcohol, bake it - there's lots of way to clean pads. I don't know whats best for what contaminant, you can try one first then move on if it doesn't work just search this forum.

    Oh yes, someone suggested you fix the leak - I would look into that too. Try to find where it's coming from first.

  6. #6
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    Sounds like the first owner cooked the fluid and it's time for a bleed.
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  7. #7
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    Sounds like you need a bleed, however if it is leaking fluid then then you may have bigger problems that need fixing 1st.

    I spent years on Juicy 7's (several generations worth) and have a had a few leaks. My experience is that if fluid is leaking out when you squeeze the lever some to most of your braking power is gong out the hole with the leaking fluid. Plus you may be adding air to the system when you release the lever which will make the problem worse.

    If you are loosing fluid and adding air the brakes will never work right.

    To clarify, was the leak on the reservoir on your brake lever on at the rear on the caliper.
    Regardless, both have a seal that at best can be out of alignment and may need to be reset or replaced. Regardless, you will need an Avid brake bleed kit. (The Juicy's will noticeably loose performance when they need a bleed). If you can stop the leak you should be good to go once you bleed (and likely add fluid which is included in the Avid bleed kit).

    If the pads are not contaminated with brake fluid, you might try cleaning by scraping with steel wool (or lightly with a dremel if you have one). This will remove any build up that can rob power. If there is fluid on the pads they are not really worth saving.


    Worst case, Pricepoint.com has the J3's for $69.
    (point being... a bleed kit is $30 and pads are usually $30) (but a bleed kit really is a must with most Hydro discs).

  8. #8
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    Thanks again for the input.

    The leak is from the reservoir (between the resevoir and cap) on the handlebars and there's a slight dribble when the lever is pulled. However, the amount that leaks is so slight I can't believe it represents a significant amount relative to the total fluid displacement generated by the lever. I read somewhere that others had experienced this with J3s out of the box so I was basically going to accept it but I guess I should investigate the seal and see if it's damaged/crimped etc.

    Bottom line is I'll buy the rubbing alcohol and bleed kit tonight and maybe get the dremmel out on the pads and hopefully by tomorrow the situation will be much improved!

  9. #9
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    As an update..

    So tonight I removed the pads, sanded them until 'clean' soaked them in rubbing alcohol and re-assembled everything. I also cleaned the surfaces of the disc with rubbing alcohol and the net effect was a very slight, but still entirely unacceptable, improvement.

    I guess the next step, assuming the the caliper/level is not defective, is to bleed the brakes and see if the issue is air in the system. The bleeding process looks like it'll also top up the system if the level fluid is low. I'll also take the lid of the reservoir and see if there's an obvious reason for the leak.

    David

  10. #10
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    Well alcohol didn't work for my dot fluid contaminated pad either - same as you - little improvement that hardly noticeable but it's worked for others. I heard that baking the pads is the best for dot fluid contamination. I just replaced the pads and that took care of it. You can try bleeding it but I highly doubt that that would take care of the problem since your lever feels solid. I think finding the leak should be a priority at this point b/c it could be the culprit for the pad.

  11. #11
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    If the seeping is between the diaphragm and cap their is too much fluid.
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  12. #12
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    I actually have the EXACT same problem, but I have juicy 5's. I am very curious to see what the problem is. My brake is very soft and almost no stopping power. I have noticed there is also a small leak except it is at the rear night beside the pad, which I assume is the problem. Please let me know what you find!

    Thanks

  13. #13
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    That's a long shot from being the EXACT same problem. His lever is normal, not soft and his leak seams to be at the reservoir cap, what takes no pressure when you apply the brakes. Your leak at the caliper does take a lot of pressure when you apply the brakes. Furthermore, your leak will in itself contaminate the pads, his will not. Yours seems like it needs new caliper seals, pads, and a bleed. His seems like it will need pads and maybe seals at the reservoir and a bleed is probably unlikely needed.

  14. #14
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    Quote Originally Posted by vk45de
    That's a long shot from being the EXACT same problem. His lever is normal, not soft and his leak seams to be at the reservoir cap, what takes no pressure when you apply the brakes. Your leak at the caliper does take a lot of pressure when you apply the brakes. Furthermore, your leak will in itself contaminate the pads, his will not. Yours seems like it needs new caliper seals, pads, and a bleed. His seems like it will need pads and maybe seals at the reservoir and a bleed is probably unlikely needed.
    Nice helpful response to juicemonkeys 1st post on MTBR.

    Yes it is a different problem, but give the guy a break. He still has a leaking brake and is looking for help.

  15. #15
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    Quote Originally Posted by juicemonkey
    I actually have the EXACT same problem, but I have juicy 5's. I am very curious to see what the problem is. My brake is very soft and almost no stopping power. I have noticed there is also a small leak except it is at the rear night beside the pad, which I assume is the problem. Please let me know what you find!

    Thanks
    Sounds like you need a bleed kit as well.

    Also may need to take the caliper apart and try to reset the seal between the two halves (I believe the J5 is a 2 piece caliper). Also make sure your hose fitting is tight. You might also try removing the pistons to make sure the sides are clean (and not damaged) and that fluid is not coming out between the piston and the caliper.

    (keep in mind that once you start taking the caliper apart you will have to bleed the system to add fluid and remove air before you can see if you fixed the problem)

  16. #16
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    The break was the part I told him what was wrong. He knew well enough it wasn't the EXACT same problem. He even stated it himself. Sry if I offend you, but I would appreciate it if when you state EXACT, that's EXACTLY what you mean.

  17. #17
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    So for those of you interested in the resolution of this issue.....

    I started by taking the cap off the reservoir, pulling out the gasket/diaphragm and cleaning everything with a soft cloth. I then reseated the gasket and reassembled the cap making sure the two screws were as tight as seemed safe. When I now pumped the lever there was no longer any sign of fluid at the joint. I'm not saying this solved the leaking problem just that it at least appears to have gone away. Could be that by removing the cap I lowered the fluid level in the reservoir and reduced the pressure as someone suggested might be reason for the leak, anyway...

    Next I bled the system, closely following the guidelines and did manage to remove what appeared to be quite a significant amount of air from both the caliper and the lever. At this point I thought I was all set and took the bike out onto the road to test. And....no improvement! When I bought the bleed kit I also picked up some new pads so I swapped them out and tried again. Still no improvement...! By this point I'm starting to get pissed. But then it occured to me that it might take a while for the pads to 'seat' (as would be the case for car) so I rode around and braked and rode and braked and after a few minutes the rear tire started to actually lock up at speed. I can tell it's continuing to improve and I imagine after a short while it'll be at full strength.

    My guess is I needed the bleed anyway, and certainly after messing with the reservoir, but the bottom line is it appears the problem was actually contaminated pads!

    Thanks again for all the input. Hope the others of you with 'similar' problems manage to resolve yours successfully as well.

    David

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