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Hyrdaulic Disc Brakes...rotor rubbing on the pad

Dazza78Dazza78 Posts: 32
edited May 2010 in MTB workshop & tech
Morning all,

Please forgive me if I get some of the technical terms wrong, but I'm fairly new to this mountain bike malarky :wink:

Right, I picked up my new Rockhopper SL Comp last Friday (love it by the way!), and have been out on some gentle xc rides around the local area, mainly consisting of dusty/hardpack/rocky/rooty trails, and believe I have 'bedded-in' the Juicy 3 SL brakes in this time.

When I got back from my first ride, which was in the evening after I had picked the bike up, I noticed a rubbing sound coming from the front. Having taken a closer look, I've noticed that there is a 1-1.5mm 'gap' between the left hand pad and the rotor, but the right hand pad is just kissing the rotor, which is obviously causing this rubbing noise.

When I put the bike in the car I take the front wheel off and I've been extremely careful in making sure the front brake lever isn't squeezed, and I've also been careful when putting the wheel back in the forks and making sure the rotor goies in cleanly between the pads etc. I don't believe the rides that I've been on are the cause of this either.

Is this just a case of me not bedding the brakes in properly and me over-reacting? Or is it just a simple case of the rotor/pads not being aligned correctly? Maybe even the wheel not being re-fitted plumb? As this is the first bike I've owned with hydraulic brakes I'm not too sure what to expect and I'm not too keen of having a fiddle around with the brakes either (all I've done is use a flat bladed screw driver to make sure the pads are fully apart) . Shall I just take it back to the LBS and get them to have a quick check or is there something 'obvious' that I'm missing?

Posts

  • diydiy Posts: 6,473
    When ever you take the wheel off for any length of time you should pack the caliper out to prevent it from closing up (which it will do, even if you don't squeeze the brakes). Your LBS will probably give you a pad spacer. If not a piece of cardboard, paper or anything reasonably firm but soft.

    Secondly, from time to time you will need to adjust your caliper positioning by slackening the mounting/adjustment bolts, squeezing the lever on and re-tightening. If your rotor starts to be off-centre, from the caliper, then pushing the pistons home and re-setting them helps.

    Basically if you pack out the caliper when you remove the wheel, you wont have this problem so much.

    Depending if you have post mount or IS mount, the adjustment nuts are the ones that screw in to either the post of the mounting bracket - see post mount example

    juicy-5-caliper.jpg
  • Dazza78Dazza78 Posts: 32
    Thanks for your reply DIY, appreciated.

    I had read previously that its a good idea to either get a spacer or a piece of cardboard to ensure that the caliper doesn't close up...bets sort something out :)

    With regard to your comments in the second para, would they need adjusting after just a under a weeks worth of use? Also, I presume the mounting/adjustment bolts the ones at the top and bottom in that picture?
  • diydiy Posts: 6,473
    correct - top and bottom bolts.

    If you have had the wheel off and not put a spacer in then the caliper pistons will have closed up. You might try gently opening them up a bit with a plastic tyre lever or similar and then put the brakes on to reset them on to the discs.

    But basically no - the benefit of hydro brakes is that they are pretty much self adjusting.

    New brakes should be low maintenance in the summer - its only winter riding that destroys them.

    However your problem is highly likely to have been caused by not using a spacer.
  • Dazza78Dazza78 Posts: 32
    Schoolboy error then :oops:

    Cheers for your help!
  • *AJ**AJ* Posts: 1,080
    To be honest, my Hayes need realigning every time i removed the front wheel, my Shimano brakes never do though.

    As said just loosen the mounting bolts so the caliper is loose pull the lever and keep it pulled whilst you nip up the bolts.
  • Dazza78Dazza78 Posts: 32
    Went to the LBS who confirmed what you said DIY :) They also said the wheel wasn't in straight enough! Ooops :lol:

    They gave me a couple of spacers so I should be free of rubbing from now on!
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