Disc brake rub

olly22
olly22 Posts: 21
edited February 2017 in The workshop
Morning all,

Lovely morning commute spoiled today by the dreaded disc brake rub!

I have a Cube Attain SL disc with 105 hydraulic discs. For some reason the front disc brake has started rubbing. I have tried to realign the caliper by loosening the direct mount bolts, squeezing the brake and then tightening, but still rubs. I have tried taking the wheel off and re-sitting it (thru axles). Other than the rotor being bent I am at a loss.

Is there any other adjustment you can make to a hydraulic disc? The only other thing I can see is that the left pad doesnt move very much. When letting go of the brake the right pad opens slightly but the left doesnt seem to move very much at all. Is there anything that controls this inward outward movement?

Thanks

Oliver

Comments

  • hopkinb
    hopkinb Posts: 7,129
    Take out the pads, push the pistons all the way back into the brake caliper, so they're flush with the caliper. I use an old flat table knife, but you could use a bleed block or be careful with a flat headed screwdriver. Put the pads back in, put the wheel back in, spin the wheel, see if it's still rubbing. You've tried the squeeze the brake trick, but if you loosen off the bolts, you can adjust the caliper by hand so there's a gap either side of the rotor, then re-tighten. Or, as you say, the rotor might be bent, but you should be able to see this if you spin the wheel and watch for which part of the rotor rubs against the brake pad. If the brakes were working with no rub before, they should stay rub-free with hydro brakes, at least that's my experience! Mine only really rub when I put new pads in, but I do all the above, and that normally sorts it out.
  • vimfuego
    vimfuego Posts: 1,783
    As above - good advice.
    Had something similar on mine once - even ended up replacing the rotor given that I just couldn't shift the rub - it made sod all difference! Eventually just loosened the caliper mounts & fettled it by hand into a position that cured the problem. All very odd given that squeezing the brakes etc usually lines it up well enough. Only other option is to remove the wheel, squeeze the brake so the pistons come out a bit (take care to ensure you keep them apart) then carefully clean around the edges with a q-tip or something, before pushing them back in as above - occasionally you can get enough accumulated crap in there that they don't release back cleanly.
    Good luck with it - I know how unbelievably annoying that noise can get once it starts bothering you.
    CS7
    Surrey Hills
    What's a Zwift?
  • cycleclinic
    cycleclinic Posts: 6,865
    push the pads back. The squeezing brake trick with the bolts loose sometimes works but sometimes it does not. The caliper sometimes does not want to sit parrallel to the disc and it has to be done by hand.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • olly22
    olly22 Posts: 21
    :D:D:D
    Thank you all. I have just used a table knife to push the pads back. Reset the mounting bolts and it now works like a dream. I look forward to a quiet ride home!

    Many thanks!

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