Sticky piston

steve_muzzy
steve_muzzy Posts: 259
edited August 2012 in MTB workshop & tech
I am having issues with my Xt rear calliper, basically one piston is moving and the other is not, the pads don't meet so not getting any breaking performance

Is there an easy fix anyone knows of ?

Comments

  • TheEnglishman
    TheEnglishman Posts: 587
    Can you push the moving piston all the way in, brace it from coming out then pump until the stuck one comes out enough for you to give it a good clean?

    Best would be to get a caliper repair kit (new gaskets and seals), split the caliper and clean it thoroughly. Then reassemble with new brake fluid.

    The first option's always worked for me, but I clean my brakes and re-grease every month.
    Please click here to sponsor me on a 100 mile charity bike ride in aid of the MS Society
  • steve_muzzy
    steve_muzzy Posts: 259
    Forged calliper so can't split, will check out online for servicing, thanks for the help
  • lesz42
    lesz42 Posts: 690
    would like to know where u can get a shimano service kit for brakes.....



    what i do is take pads out, spray with wd40, use a spoon or blunt knife and pump lever and work the piston/s in and out, wash again with wd40, and repeat

    being VERY careful not for the pistons to pop out!

    once free, wash with IPA, very well, wipe dry, put pads back!
    Giant Trance X0 (08) Reverb, Hope Hoops 5.1D, XT brakes, RQ BC, Works Components headset 1.5
  • steve_muzzy
    steve_muzzy Posts: 259
    lesz42 wrote:
    would like to know where u can get a shimano service kit for brakes.....



    what i do is take pads out, spray with wd40, use a spoon or blunt knife and pump lever and work the piston/s in and out, wash again with wd40, and repeat

    being VERY careful not for the pistons to pop out!

    once free, wash with IPA, very well, wipe dry, put pads back!

    Let's say the piston fell out but landed on a carpet ......
  • Greer_
    Greer_ Posts: 1,716
    Clean it, then pop it back in! Will probably need bled now though.
    Orbea Alma Team Carbon - Strava -Specialized Allez Sport
  • Neal_
    Neal_ Posts: 477
    I wouldn't use WD40 on any rubber seals, they don't like it. Silicone spray is suitable for rubber and plastic so this should be fine, remove wheel and pads then spray some on pistons and work them in and out until they both move freely. Clean with water and maybe some diluted IPA before replacing pads and wheel but I'm pretty sure IPA is bad for seals too so go easy with it.
  • lesz42
    lesz42 Posts: 690
    ipa is fine, solvents not so good, Silicone can damage as well
    Giant Trance X0 (08) Reverb, Hope Hoops 5.1D, XT brakes, RQ BC, Works Components headset 1.5
  • Neal_
    Neal_ Posts: 477
    IPA is a solvent and silicone spray lube is specifically for rubber and plastics so is highly unlikely do damage any seals (e.g. Fork Juice is silicone and is all good for stanchion seals).

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