Narrow Disc Brake Caliper Mount? Alignment woes!

EarlofBarnet
EarlofBarnet Posts: 673
edited July 2012 in MTB workshop & tech
I've recently picked up an Orange Evo 8 and have set about swopping some parts from my old bike to the Orange. I've hit a snag when trying to align the rear brake caliper. I can't get the brake caliper mounted far enough across to centre the disc in the caliper.

e0294ff8.jpg

I need to move the caliper further to the left (in the picture), but have no adjustment left on the caliper, it's as far across as it'll go. The caliper mount is a cheap one so just wondered if a Shimano one may be narrower or if anyone knows of a narrower mount?

Set-up is a Deore brake and a XT hub. Deore brake is fine when used with a Deore wheel, although the caliper is a little close to the disc. So can only think the spacing of the XT hub is different to the Deore one and is causing the issue. Wheel and disc were fine on previous frame too.

Any help with the mount would be much appreciated.

Thanks in advance, Matt

Comments

  • nicklouse
    nicklouse Posts: 50,675
    get the Frame brake mounts faced. it will help.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • EarlofBarnet
    EarlofBarnet Posts: 673
    Spot on, will see if a local shop has the tools to do it. Thought a mount may be a cheaper/easier option. Found some posts with people saying Avid mounts are thinner. Think I need 1mm maybe a little more, would it be ok to shave this amount off the frame mount?
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    Yes, as long as the caliper has movment to compensate.
  • nicklouse
    nicklouse Posts: 50,675
    EarlofBarnet wrote:
    Spot on, will see if a local shop has the tools to do it. Thought a mount may be a cheaper/easier option. Found some posts with people saying Avid mounts are thinner. Think I need 1mm maybe a little more, would it be ok to shave this amount off the frame mount?
    ir will make no difference if the mounting holes are all in the same place.

    or you could get the mount machined on the side that mounts onto the frame.

    the problem is not the thickness of the mount but the positions of the holes as your caliper does not have enough movement.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • .blitz
    .blitz Posts: 6,197
    EarlofBarnet wrote:
    So can only think the spacing of the XT hub is different to the Deore one and is causing the issue.
    Unlikely bud - I swapped some Deore wheels for some XT wheels (inc rotors) and they went back in with zero adjustment to the brakes the rotors were in exactly the same position.

    Same goes for the adaptors Avid/Shimano/Superstar/NSB/Hope I've tried 'em all and the finish varies a bit but dimensionally they have all been spot-on
  • Barteos
    Barteos Posts: 657
    You can

    1. Put an extra thin washer between the frame dropout and the L locknut. (not perfect but takes seconds)
    or
    2. Enlarge the brake caliper slots with a file. (the simplest practical method)
    or
    3. Remove some thickness (frame side) from the adapter by sanding it on a flat piece of sand paper.
    or
    4. Find someone with a milling machine :)
  • nicklouse
    nicklouse Posts: 50,675
    .blitz wrote:
    EarlofBarnet wrote:
    So can only think the spacing of the XT hub is different to the Deore one and is causing the issue.
    Unlikely bud - I swapped some Deore wheels for some XT wheels (inc rotors) and they went back in with zero adjustment to the brakes the rotors were in exactly the same position.

    Same goes for the adaptors Avid/Shimano/Superstar/NSB/Hope I've tried 'em all and the finish varies a bit but dimensionally they have all been spot-on
    but again the number of rotors i have had to shim to get them to match another set...

    as bearings wear the adjustment moves the cones in. which means that no two hubs will always have the same dimensions.

    but as the wear reduces the OLD. it moved the disc mounting face out. which would just make things worse in this case.

    Suppose the rotor may not be seated correctly.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • EarlofBarnet
    EarlofBarnet Posts: 673
    Thanks for the comments everyone. Going to whip the rotor off and check it'll seat ok and re-mount, see I that helps. Then if no joy will get the mount faced. Frustrating!
  • .blitz
    .blitz Posts: 6,197
    nicklouse wrote:
    as bearings wear the adjustment moves the cones in. which means that no two hubs will always have the same dimensions.
    Not entirely sure I follow that me being a bit thick like would you care to elaborate :?
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    say your bearings and cups wear from new 1mm so the ball have less circumferance and the walls are thinner. Same happens both sides. You tighten the cones to compensate thus moving the locknut and where the frame rests on axel inwards giving a shorter effective axel length of 2mm. This moves the drop-out inwards when tightened by the QR so the mount will have moved by that flex really.
  • .blitz
    .blitz Posts: 6,197
    Ah OK I was thinking about the hub itself I never thought about the frame/forks flexing

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