Sticky Piston on M596

paulneenan76
paulneenan76 Posts: 777
edited July 2015 in MTB workshop & tech
Hello All

Gotta sticky piston on the rear - Shimano M596 - and whilst I got it working sufficiently for a recent boys weekend in Afan, it is now stuck again. Anyone got any easy and sure-fire remedies or is it new brake time?

Thanks

Paul
Family, Friends, Fantastic trails - what else is there

viewtopic.php?f=10017&t=12898838
viewtopic.php?f=10017&t=12897374

Comments

  • jimothy78
    jimothy78 Posts: 1,407
    Take brake off bike and remove pads.
    Whilst holding in the non-sticky piston, carefully press brake lever to advance sticky piston about 5mm (too far and it will fall out completely - not helpful).
    Clean piston sides with cotton bud dipped in IPA.
    Press piston back in, then repeat the above process.

    Check for stickiness by pressing the brake lever without holding the opposite piston - both should move the same distance, and also retract equally when the lever is released. If not, repeat cleaning process.

    If you can't get equal (and smooth) movement after several iterations of the above cleaning process, you can try lubricating the edge of the piston at the point where it enters the seal (before pushing it back in) with a tiny amount of mineral oil (the end of a toothpick just dipped in oil is good for this job).
  • The Rookie
    The Rookie Posts: 27,812
    As above, but I don't use IPA but brake fluid (Mineral oil for Shimano), you'll often need to do the 'good' piston when you are finished as the sticky one will move more freely!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • paulneenan76
    paulneenan76 Posts: 777
    Thanks

    Not sure I have any IPA (not that sort anyway), would a small amount of Turps Substitute and some muc-off wet lube be ok?

    Paul
    Family, Friends, Fantastic trails - what else is there

    viewtopic.php?f=10017&t=12898838
    viewtopic.php?f=10017&t=12897374
  • The Rookie
    The Rookie Posts: 27,812
    Definitely not wet lube and terps sub' may damage the seals, the brake fluid or maybe white spirit at a push.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Herdwick
    Herdwick Posts: 523
    after cleaning with IPA apply some light grease with an ear bud on the piston and work it a few times then clean off excess grease from the caliper. take care not to contaminate pads, clean before you fit the pads, do this to the other caliper as well.
    “I am a humanist, which means, in part, that I have tried to behave decently without expectations of rewards or punishments after I am dead.”
    ― Kurt Vonnegut
  • The Rookie
    The Rookie Posts: 27,812
    Grease will attract more dirt than brake fluid, some greases can dry out and cause problems (such as lithium grease) which is why I think the correct brake fluid is the right option.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Herdwick
    Herdwick Posts: 523
    light grease, not grafite, not marine grade, HD etc. more or less like vaseline. and WIPE OFF any excess to avoid attracting dirt
    this may be helpfull
    http://www.bikeradar.com/gear/article/how-to-service-hydraulic-disc-brake-calipers-video-43227/
    “I am a humanist, which means, in part, that I have tried to behave decently without expectations of rewards or punishments after I am dead.”
    ― Kurt Vonnegut

Categories