Rear Brake Caliper Won't Tighten in Frame

wilky27
wilky27 Posts: 200
edited March 2015 in Workshop
Hi,

Having an issue with my rear brake caliper in that it won't tighten in the frame. After only a few miles of ridding i find it's moved and i'm getting brake rub. The frame is a Planet X N2A and the calipers are Campy skeleton, although I've tried with other calipers and have the same issue. I'm using an alloy washer and have tried a range of different size bolt on the inside, it just won't tighten. I'm not sure what max torque I can put on it but have gone pretty hard without hanging off it, as I'm worried about damaging the carbon frame.

Has anyone had any similar issues and can provide any help?

Many thanks.

Comments

  • dgunthor
    dgunthor Posts: 644
    first, check the thread is ok by attaching the bolt on the caliper off the bike

    it might be the alloy washer is allowing it to turn - get hold of a serrated star washer from a hardware store (B&Q etc) which will give some grip and stop it turning
  • wilky27
    wilky27 Posts: 200
    Thanks for the reply.

    The washer on the caliper is serrated. I've also tried another caliper which won't tighten either so I'm thinking it's something to do with the boss in the frame (or whatever it's called?)

    I'll nip to B&Q tonight to see if I can find any different washers.
  • wilky27
    wilky27 Posts: 200
    This is the washer it's currently using:

    http://www.totalcycling.com/en/Campagno ... tedKingdom
  • bianchibob
    bianchibob Posts: 306
    You refer to a bolt that you are tightening up. My experience is that it is not a bolt but a theaded sleeve with an Allen key fitting to tighten it.
    Have you measured the length of the sleeve compared to the width of the brake fitting on the frame.
    If the sleeve id fractionally too long it will not tighten and the caliper will rotate on the sleeve in the frame boss.
    I think you buy sleeves of different lengths. This might be your answer.
  • wilky27
    wilky27 Posts: 200
    Hi,

    Yes it's a sleeve. The caliper came with 3 different lengths and I've tried them all to no avail.

    Thanks.
  • keef66
    keef66 Posts: 13,123
    With the caliper off the bike, when you thread one of these tubular nuts on to the mounting bolt, can you screw it all the way down to the caliper, or does it stop some way short because the threads on the bolt do?

    And do you have 2 serrated washers, one each side of the mounting boss? (I think some photos on the web show 2...)

    I can't imagine any other explanation for what you describe...
  • wilky27
    wilky27 Posts: 200
    No the smallest bolt stops well short. And I don't think I'd get another washer over the sleeve as it's too wide. Plus the sleeve kind of goes inside the frame, and the hole is just big enough for the sleeve, where would the washer go?

    Thanks.
  • rafletcher
    rafletcher Posts: 1,235
    Try using a hacksaw to reduce the length of one of the sleeve nuts to less than the shortest you currently have - that's the only thing I can think of (bolt bottoming out) unless you just aren't tightening them up enough.
  • wilky27
    wilky27 Posts: 200
    Well that might be the issue. I tighten it pretty hard but don't want to damage the frame.

    ta.
  • keef66
    keef66 Posts: 13,123
    wilky27 wrote:
    No the smallest bolt stops well short. And I don't think I'd get another washer over the sleeve as it's too wide. Plus the sleeve kind of goes inside the frame, and the hole is just big enough for the sleeve, where would the washer go?

    Thanks.

    An extra washer on the mounting bolt before the nut goes on?
  • wilky27
    wilky27 Posts: 200
    keef66 wrote:
    wilky27 wrote:
    No the smallest bolt stops well short. And I don't think I'd get another washer over the sleeve as it's too wide. Plus the sleeve kind of goes inside the frame, and the hole is just big enough for the sleeve, where would the washer go?

    Thanks.

    An extra washer on the mounting bolt before the nut goes on?
    On the caliper side of the frame? Yeah I'll try that!

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