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  1. #1
    mtbr member
    Reputation: Mark16q's Avatar
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    Sticky Xtr Disc piston

    Hello MTBR,

    New on the board, but long time mtb'r. Have had great luck with my XTR stuff until recently. It's vintage 2004 with discs. Problem is, on my rear caliper one of the pistons isn't fully retracting after braking. So it drags just enough to squeek. Maddening little squeek that gets worse as they heat up. I've bled them, have new pads, and recentered repeatedly.

    Just replaced the pads on a friend's bike with the same setup, and both pistons retract completely. 2 minutes to replace the pads and it's perfect. I know mine "should" work like this, but something is amiss.

    Any ideas?

    Thanks,

    mg

  2. #2
    mtbr member
    Reputation: jammin's Avatar
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    I feel your pain, my 2005 XT Hydro disc do the same thing, front is fine but the back does the same as yours and i only have 4 rides on my bike., still trying to figure it out

  3. #3
    Cereal Killer
    Reputation: chadmeeh's Avatar
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    I had the same problem on my XT's. Someone told me to take the pads out (with the piston still sticking out) and put a few drops of the Shimano hydro fluid on the exposed part of the piston. Then gentley push it back in, put the pads back in, re-mount the wheel and cycle the brake a few times. Worked like a charm for me, no more problems with mine.

  4. #4
    Gimme my MOJO!
    Reputation: leleklegrunt's Avatar
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    Quote Originally Posted by chadmeeh
    I had the same problem on my XT's. Someone told me to take the pads out (with the piston still sticking out) and put a few drops of the Shimano hydro fluid on the exposed part of the piston. Then gentley push it back in, put the pads back in, re-mount the wheel and cycle the brake a few times. Worked like a charm for me, no more problems with mine.
    If you want to be thourough, you should oil the piston, push them back in, then using a tire level to hold the OTHER piston in, pump on the lever to pump out the sticky piston again. Push back in and repeat 4-6 times.

    Repeat with other piston just to be sure, then wipe down everything, since you are going to have oil everywhere (from the oiling, NOT from the caliper leaking out! If it does, you have pushed the piston too far out and now need to re-bleed!)

    Assuming you removed the wheel beforehand, (to stop oil getting onto the rotors) reinstall the wheel, reinstall the pads, center, and you should be good to go...

  5. #5
    Cereal Killer
    Reputation: chadmeeh's Avatar
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    Quote Originally Posted by leleklegrunt
    If you want to be thourough, you should oil the piston, push them back in, then using a tire level to hold the OTHER piston in, pump on the lever to pump out the sticky piston again. Push back in and repeat 4-6 times.

    Repeat with other piston just to be sure, then wipe down everything, since you are going to have oil everywhere (from the oiling, NOT from the caliper leaking out! If it does, you have pushed the piston too far out and now need to re-bleed!)

    Assuming you removed the wheel beforehand, (to stop oil getting onto the rotors) reinstall the wheel, reinstall the pads, center, and you should be good to go...
    Good suggestion about oiling the piston more than a few times. As far as wiping everything down, and taking the wheel out before doing anything, i figured would be understood. But thanks for the backup on that. Never can be too thorough when explaining stuff.

  6. #6
    I already rode that
    Reputation: SuperNewb's Avatar
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    Hearing a lil squeek might also mean the rotor is dragging on the caliper. Mine were from that SPS issue from the same year brakes. Doing what was suggested did help but the problem always returned for me after afew short rides or even 1 ride. I sent them back and got new replacements and havent had a problem since. (untill I installed some goodridge hoses...buts thats a diff sorta issue)
    Riding F/S since oct 94'

  7. #7
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    Reputation: SSteve F's Avatar
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    I have been fighting this issue for two years with my XT's.

    Couple of things you may want to check:-
    - it is possible to have air trapped in the caliper and not to be able to get it out with a basic bleed kit. You may want to have your LBS do the bleed (presuming they have the correct equipment)
    -make sure you have no kinks in your hoses. These may not allow the fluid back into the reservoir thus causing the drag.
    It's only pain......

  8. #8
    I already rode that
    Reputation: SuperNewb's Avatar
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    Quote Originally Posted by SSteve F
    I have been fighting this issue for two years with my XT's.

    Couple of things you may want to check:-
    - it is possible to have air trapped in the caliper and not to be able to get it out with a basic bleed kit. You may want to have your LBS do the bleed (presuming they have the correct equipment)
    -make sure you have no kinks in your hoses. These may not allow the fluid back into the reservoir thus causing the drag.
    There was some air in the rear when I rebled them and as for kinks...there are none in the hoses either, visually anyways. LBS wouldve bled them the same way I did unless they have some fancy piece of equipement. (bled both ways through the lever and caliper).
    Riding F/S since oct 94'

  9. #9
    mtbr member
    Reputation: Mark16q's Avatar
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    Thanks for all the info here. I think the only fix will be calling Shimano about replacement

    I've lubed the pistons, rebled and centered, and can get a couple of rides in before the probem re-occurs. Did a lot of downhill today, and by the end, drag was back due to the one piston not returning. I hate being off the bike to replace stuff, but my bike was scaring animals and small children with all the noise.

    mg

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