Movement in break calipers

richardjallen
richardjallen Posts: 691
edited June 2007 in Workshop
Its possible to turn my break calipers about the bolt that fixes them to the fork/seatstays by hand. This results in one caliper touching the rim while the other is away from the rim. This can happen after breaking while on a ride and I can hear the pad scraping the rim. I have tightened the bolt to between the specified torque levels but it has not helped. I don't want to over tighten them as its a carbon fram/fork so I dont want to crush it.

Any ideas?

Comments

  • pbiggs
    pbiggs Posts: 9,232
    Look into replacing or adding washers. Differently sized/shaped washers might do the trick.

    I appreciate the concern about crushing, but still a little tighter might be possible. Are your forks 100% carbon? Most have alloy crowns.

    <i>~Pete</i>
    <i>~Pete</i>
  • on the road
    on the road Posts: 5,631
    Or add more washers.
  • richardjallen
    richardjallen Posts: 691
    When I said 'one caliper' in my OP I ment break pad. The problem effect both the front and the rear caliper. I'll try different washers. I'm guessing larger diameter washers rather than washers with more thickness.
  • monty_dogcp
    monty_dogcp Posts: 382
    If the centre bolt is tight enough, it should be firm hand pressure and it shouldn't be possible to just move the brake caliper mount by hand. If the centre bolt is tight, then it could be that the spring tension isn't balanced - on most modern dual-pivot brakes, you'll find a small grub screw on one of the arms which uses a tiny allen key or small screwdriver. If the arm with the screw is rubbing the wheel, try tightening the screw a couple of turns, or alternatively, if it's the other, try unscrewing it. When you pull the brake lever on, both pads should spring back equidistant from the rim. If still no joy, then you may need to dismantle the caliper to make sure that the pivots/springs and moving freely and other bolts done-up tightly.
  • richardjallen
    richardjallen Posts: 691
    I think it really is the centre bolt. While standing in front of the front wheel and looking down at the calliper. If I put fingers under the metal break shoes and my thumbs on the top near the bolt I can move the callipers and see the serrated washer around the bolt turning. Currently the bolt is tightened to about half way between the upper and lower torque limits. I will try tightening to the upper limit but I think its reasonable to suggest the calliper should hold in place even at the lower limit.
  • richardjallen
    richardjallen Posts: 691
    Tightening to the maximum torque limit seems to have sorted it.

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