Brake Centering Weirdness

photonic69
photonic69 Posts: 2,423
edited October 2015 in Workshop
The rear 105 caliper on my bike seems to have a mind of its own.

On Sunday went out for a ride. Noticed that before setting off the caliper was not centered so pad was rubbing one side. Adjusted and applied brakes a few times. 15 miles later noticed pad rubbing again on other side. Adjusted again. All OK. At end of ride checked it over. Pads not quite centered but not rubbing. Reset again.

Yes - caliper mounting bolt is done up tight!

Was getting a bit of brake noise/squeal/harmonics/vibration from it so guess toe in needs setting again. Could this vibration be enough to cause the caliper to move?

Weird one. Any ideas?


Sometimes. Maybe. Possibly.

Comments

  • redvision
    redvision Posts: 2,958
    Check the wheel is true and centred correctly in the dropouts.
  • photonic69
    photonic69 Posts: 2,423
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19726387#p19726387]redvision[/url] wrote:
    Check the wheel is true and centred correctly in the dropouts.

    It should be as I always tighten QR when bike the right way up with a load on the saddle. It might be that I was leaning a bit. Will check next time.


    Sometimes. Maybe. Possibly.

  • keezx
    keezx Posts: 1,322
    [quote="PhotoNic69

    Yes - caliper mounting bolt is done up tight!

    [/quote]

    Mounting nut too long so it feels tight but the caliper is not?
  • PhilipPirrip
    PhilipPirrip Posts: 616
    May be obvious but were you adjusting the spring to centre it? If you adjust it by the bolt or move the whole caliper by hand and the spring is off-centre in all likelihood the caliper will be off-centre again as soon as you apply it.
  • photonic69
    photonic69 Posts: 2,423
    Caliper seems pretty tight to the frame so no side to side movement (well there is but don't know why)

    Centering was done by the adjustment screw on the caliper arm, not by moving the caliper itself. Brakes pumped by hand 10 times to make sure they were centered etc.


    Sometimes. Maybe. Possibly.

  • darkhairedlord
    darkhairedlord Posts: 7,180
    I've seen this before, sometimes it's the cable outer too long or too short, so you apply/release the brakes and it pulls the calliper out of alignment.
  • Rightarmbad
    Rightarmbad Posts: 216
    How high does the little adjust screw stick out?
    If it is far out there can be inconsistent centreing.

    Set it so that the base of the head is level with the surface of the caliper.
    Then move the whole assembly on the mount to get it centered.
  • Bobbinogs
    Bobbinogs Posts: 4,841
    Might also be worth checking the wheel to see if there is some play in the bearings...
  • photonic69
    photonic69 Posts: 2,423
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19727810#p19727810]Rightarmbad[/url] wrote:
    How high does the little adjust screw stick out?
    If it is far out there can be inconsistent centreing.

    Set it so that the base of the head is level with the surface of the caliper.
    Then move the whole assembly on the mount to get it centered.

    This could be the thing. I'm getting some mud guards so when i fit these I'll reset everything and go from there. I think the little screw is out further than I'd expect it to be.


    Sometimes. Maybe. Possibly.

  • photonic69
    photonic69 Posts: 2,423
    Ah! Feel like a right plonker!

    I adjusted the brakes initially when I had my spare turbo wheel fitted. Didn't think about it when I refitted my usual rear wheel. It was then that the rubbing started. One wheel is slightly more dished than the other, hence the rub. Silly, stupid oversight!

    Thanks for the input chaps. Problem solved. Just need to get mudguards fitted (when they arrive!)

    Nic


    Sometimes. Maybe. Possibly.

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