New Shimano Deore Disc Brake Pads Rubbing Against Rotor

martastik
martastik Posts: 6
edited February 2009 in MTB workshop & tech
Several weeks ago, I bought a new MTB which has Shimano Deore M525 hydraulic disc brakes fitted. The rear one seems to be fine, with only very occasional rubbing of the pads against the rotor. But with the front one, the right hand pad seems to be in continuous contact with the rotor, meaning that the wheel will not spin very freely. The clearance seems to be very fine.

I've been back to the bike shop twice (a major chain in London) and both times they told me there is nothing more they can do to improve them and this is 'within normal tolerances' for a new brake. They also thought that there may be very slight warping of the rotor, which they said occurs normally due to getting hot during braking.

After the second trip to the bike shop, the wheel was spinning a bit more freely, but then I took the front wheel off to take the bike home in my car. On getting home, I put the wheel on again and there was more resistance on spinning the wheel than before.

Is this something that will improve in time, or am I being fobbed off?

Is there a simple check or adjustment I could perform to save another trip back to the shop, which is not exactly round the corner?

Any help much appreciated.

Comments

  • ride_whenever
    ride_whenever Posts: 13,279
    have a read of the park tools disc brake thing, you need to re-center the brakes, which from the sounds of things will involve spacing the caliper a bit further.

    Is it constantly rubbing, or sort of on-off rubbing? If on-off then the rotor might be bent slightly.
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  • nicklouse
    nicklouse Posts: 50,675
    it also sounds like you have inadvertently moved the brake lever during transport. push the pads home again and then apply the brakes and let them settle in again.

    and yes they will get better with use.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • 13ADL1X
    13ADL1X Posts: 151
    Also worth having a look at some of the tech videos on the Hope website. There's one about centering your disc. Involves gently placing a small screwdriver behind the pad that ISN'T touching the pad and pulling the lever.
    The trail is long and my legs are burning but I can't stop smiling.
  • martastik
    martastik Posts: 6
    Those videos look very useful - cheers :) The Hope brakes in the videos look similar to my Shimanos.

    Here's the link to the videos:

    http://www.hopegb.com/page_mep_force_4.html
  • nicklouse
    nicklouse Posts: 50,675
    martastik wrote:
    Those videos look very useful - cheers :) The Hope brakes in the videos look similar to my Shimanos.

    Here's the link to the videos:

    http://www.hopegb.com/page_mep_force_4.html

    wow http://www.bikeradar.com/forum/viewtopic.php?t=12568886
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Billyounger
    Billyounger Posts: 18
    I had this problem, you need to re bleed the brakes then re postion the caliper but do not do this unless you are trained or have mechanical knowelge, some times one piston works better than the other so one pad is in contact with the rotor, which then rubs now and again , I understand this as i am a motorcycle mechanic, some shops i dont think the guys are trained or experinced enough to understand the workings of a disc brake try a diffrent shop maybe ? after pads have worn a bit you may have to re adjust the caliper ,i hope this helps.

    Shot down in flames :lol:
  • nicklouse
    nicklouse Posts: 50,675
    Billyounger
    why do you need to bleed the brakes?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • williamw1987
    williamw1987 Posts: 58
    I had this happen recently after switching to a new fork. It turned out that I had over tightened the thing that holds the wheel to the fork (excuse my lack of bike knowledge lol) and causing the forks to bend inwards causing the disc to rub as the caliper was not completely straight. I loosened it slightly so the forks were no longer under tension bending inwards and the rubbing vanished.

    What is the bit that holds the wheel to the forks called? I'm still learning the names of things... thanks chaps :)
  • forgotrafe
    forgotrafe Posts: 637
    williamw1987 wrote:
    What is the bit that holds the wheel to the forks called? I'm still learning the names of things... thanks chaps :)

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  • Billyounger
    Billyounger Posts: 18
    Hi Nicklouse,
    Because the brakes may still have some air in them that is trapped behind one piston, And thats why that piston does not move out as far as the other which in turn means that one piston moves out further so it stays out and rubs the rota, also the brake is not as powerfull as it should be and that brake pad wears more . Thats why all the manuals say push back the pistons and hold back whilst bleeding.Even the ready assembled new brakes may need a bleed after bedding / running in and re setting up :idea:

    Happy days
  • chadp
    chadp Posts: 1
    I am having the same problem on my brand new bike as well. I haven't even had the chance to ride it yet due to the fact that if it's something major the bike must be in like new shape to return it. I bought a Iron Horse Quantum 2 mountain bike and didn't realize that it was rubbing until I got it home. Could anybody give me any suggestions as how to fix this problem other then a return? :?:
    martastik wrote:
    Several weeks ago, I bought a new MTB which has Shimano Deore M525 hydraulic disc brakes fitted. The rear one seems to be fine, with only very occasional rubbing of the pads against the rotor. But with the front one, the right hand pad seems to be in continuous contact with the rotor, meaning that the wheel will not spin very freely. The clearance seems to be very fine.

    I've been back to the bike shop twice (a major chain in London) and both times they told me there is nothing more they can do to improve them and this is 'within normal tolerances' for a new brake. They also thought that there may be very slight warping of the rotor, which they said occurs normally due to getting hot during braking.

    After the second trip to the bike shop, the wheel was spinning a bit more freely, but then I took the front wheel off to take the bike home in my car. On getting home, I put the wheel on again and there was more resistance on spinning the wheel than before.

    Is this something that will improve in time, or am I being fobbed off?

    Is there a simple check or adjustment I could perform to save another trip back to the shop, which is not exactly round the corner?

    Any help much appreciated.

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