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  1. #1
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    slight pad to rotor rub...how to fix?

    I have M785 brakes (brand new)...installed the front and made sure the piston was flush with the inside of the caliper...put two bolts on, squeezed lever and then tightened bolts...still have a slight pad to rotor rub and dont know what else to try? Suggestions?
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  2. #2
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    Quote Originally Posted by ddublu View Post
    I have M785 brakes (brand new)...installed the front and made sure the piston was flush with the inside of the caliper...put two bolts on, squeezed lever and then tightened bolts...still have a slight pad to rotor rub and dont know what else to try? Suggestions?
    Push pads al the way out....

    Eyeball the caliper re set straight and true with the rotor.....and centered.

    Slowly squeeze lever observe pistons move to rotor...do they both move the same...

    Release lever do both pistons retract the same amount????

  3. #3
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    In the event that the rub is periodic as the wheel spins, the rotor is slightly warped and can be corrected gently by hand. If the rub is constant, keep working to get the caliper centered; it often takes a few tries.

    Good luck,
    Pete
    I can barely get my mouth around it.

  4. #4
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    Often times the 'squeeze the lever and tighten the bolts' method just gets you 'close'.
    1. Loosen them both just enough that you can 'just' move the caliper.
    2. Spin the wheel and listen for zinging while moving the caliper around to find the sweet spot. Slightly tighten the bolts...just to hold it there.
    3. Eye the clearance at that point, both from head on with the caliper and from behind/above (depending on whether front or rear), looking for even clearance on both sides of the rotor and also from leading to tailing edge of the pads...ie, you don't want the pads approaching the rotor caddywampus. Also squeeze the lever, if it feels somewhat dull/soft it is probably because the pads aren't hitting the rotor square.
    4. when you get everything lined up, slowly snug the bolts a little at a time, alternating between the bolts.
    5. Spin wheel and slightly drag brakes to listen for the pads hitting the rotor poorly, (catching the vents/clean out slots in the rotor). If this is happening, readjust.

    A lot of times, crappy feel at the lever has to do with the pads contacting the rotor poorly, and or unevenly, causing rotor flex and just crappy brake feel and pad life in general.

    It gets easier the more you do it. Like Pedalphile said, if the rotor has an area that is zinging off the pads every revolution, locate it, and then put a little pressure on it to persuade it to be straighter. A little at a time...don't go trying to herk it too much. Generally, find the area and center your pressure over one of the spoke locations of the rotor.

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