Disc rubbing - driving me mad!

mudcow007
mudcow007 Posts: 3,861
edited October 2011 in MTB workshop & tech
hello all

my front disc brake is rubbing, I bought the brake (Clarks S2) brand spanking new

fitted the mount to my Z1's attached calliper to mount. pulled brake lever - kept lever pulled in tightened up calliper bolts = brake rub

loose try again = brake rub

flip bike over check rotor is straight, it is

take calliper off an try to push piston back...i think it may have moved a mm if that

refit still rubbing

its driving me nuts

also when the brake is rubbing there is absolutely no power what so ever in the brake, ive run it now for over 40 miles so should be bedded in by now

any ideas?
Keeping it classy since '83

Comments

  • Slack
    Slack Posts: 326
    You might need to put a spacer shim (thin washer) between the caliper mounting and fork, to adjust the caliper position.
    Plymouthsteve for councillor!!
  • andyg1966
    andyg1966 Posts: 63
    pulled brake lever - kept lever pulled in tightened up calliper bolts = brake rub

    Thats actually the wrong way to do it. Centre the caliper on the disc with the pads removed and then fit the pads with both pistons fully retracted. Pads should move in an equal amount.

    You may have a sticky piston in which case one side will always rub.

    See the Hope videos on how to centre a brake, my advice taken from this video.

    --
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  • gtd.
    gtd. Posts: 626
    link to hope video
    How to - Set up a caliper
    How to - Centralise pistons
    Mountain: Orange Patriot FR, SubZero & Evo2LE.
    Road: Tifosi Race Custom.
    Do it all bike: Surly Disc Trucker 700c/29er
  • allthegearnoidea
    allthegearnoidea Posts: 4,077
    It's one of those jobs that can take 5minutes or 5 hours! Lol
    Chances are the disc has a minor warp, most doo, had many new ones like it!
    As said, push pistons back in, refit pads, line ip as central as oou can nd nip op the bolts, quick couple of lever pulls to check equal pad movement snd check from there,
    Assuming they are post mount, if IS mount then you'll need approximately a gazzillion shims of varying thickness as your bound to drop some!! But painstakingly swapping and adding shims to get spot on!
    As said, it can take 5 minutes or hours!!

    Is also well worth opening up the pad spring if you can to help push the pads apart more! Mine on the hopes are close to 45degree opened out! :D
    Timmo.
    After all, I am Cornish!
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  • The Northern Monkey
    The Northern Monkey Posts: 19,174
    andyg1966 wrote:
    pulled brake lever - kept lever pulled in tightened up calliper bolts = brake rub

    Thats actually the wrong way to do it. Centre the caliper on the disc with the pads removed and then fit the pads with both pistons fully retracted. Pads should move in an equal amount.

    You may have a sticky piston in which case one side will always rub.

    See the Hope videos on how to centre a brake, my advice taken from this video.

    --

    its not the wrong way.... its 1 of many different ways.
    Santa Cruz Butcher
  • The Rookie
    The Rookie Posts: 27,812
    Some callipers twist slightly as you do the bolts up, the disc not vbeing stiff enough to prevent it, so you have to do the two bolts up a tiny amount at a time alternating, if I don't do that on my Juicy's it never sits straight, do it and it's great!

    Simon
    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.
  • mudcow007
    mudcow007 Posts: 3,861
    thanks for the all advice people!

    spoke to the manufacturer on Friday who after i explain what i had tried told me to send it back as faulty an will be sending a new un out this week

    result!

    fingers crossed i can the new one aligned

    i tried taking the pads out an pushing the pistons back - they would move a tiny amount, mount the calliper pull the lever an the pistons would just go back to exactly where they were earlier

    i reckon sticky pistons my self
    Keeping it classy since '83
  • tbikeradar
    tbikeradar Posts: 129
    i have a similar problem.....what is the best remedy for sticky pistons?
  • cooldad
    cooldad Posts: 32,599
    Bit of brake fluid.
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