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Thread: Pulsing Juicy

  1. #1
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    Pulsing Juicy

    So I have a relatively new (around 250mi ish) 2007 J7. I like the brake fine but when I always light to moderate pressure to cut some speed it pulses. There is no lever feed back it just feels like your on a sine wave. They're going to be bleed soon already but will that solve the problem? I was thinking the rotor is out of true; which it is but not a whole lot. Uneven pad wear? Pads not broken is properly? Any other thoughts?

    Thanks

  2. #2
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    It doesnt take much to cause the lever to pulse from a bad rotor, sounds like you diagnosed your problem.

    http://www.utahmountainbiking.com/fix/diskrotortrue.htm
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  3. #3
    Meh.
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    Check fastener torque. Check hub/pivot bearings for play. Check spoke tension. Check that the caliper is centered properly. Check the pads for even wear. Proper break-in is pretty crucial.

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    Quote Originally Posted by dogonfr
    It doesnt take much to cause the lever to pulse from a bad rotor, sounds like you diagnosed your problem.

    http://www.utahmountainbiking.com/fix/diskrotortrue.htm
    Its pretty significant though, which is why I was leaning away from the rotor ...Nevertheless you know a lot more than me about brakes.

    Check fastener torque. Check hub/pivot bearings for play. Check spoke tension. Check that the caliper is centered properly. Check the pads for even wear. Proper break-in is pretty crucial.
    Okay! Thanks for the list! Although the caliper is pretty center, that's about the only thing I obsess about brakes, centered with no rubs or dings.

  5. #5
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    Quote Originally Posted by Renovatio
    Its pretty significant though, which is why I was leaning away from the rotor ...Nevertheless you know a lot more than me about brakes.



    Okay! Thanks for the list! Although the caliper is pretty center, that's about the only thing I obsess about brakes, centered with no rubs or dings.
    Just because it's not rubbing doesn't mean that the caliper is centered and square.

    Also check that the pads aren't grabbing at the arms of the rotor.

  6. #6
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    Quote Originally Posted by XSL_WiLL
    Just because it's not rubbing doesn't mean that the caliper is centered and square.

    Also check that the pads aren't grabbing at the arms of the rotor.
    I follow avid's instructions by loosing the bolts, pumping it a few times and holding while tightening the bolts...or something like that. Rinse repeat a few times. Is there a better way?

  7. #7
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    Check for dark spots....

    on the rotor. Just finished with a customer that had the same problem on a set of shimano brakes. Turns out there was a big old finger print on the rotor that misssed being cleaned off. Made a bit of a dark spot where extra pad material had collected and was causing the brake to pulse, no lever feed back or anything else, just a quick pusle as that spot passed through the pads. A light sanding of the rotor and pads and a good cleaning with alcohol solved the problem.

    Good Dirt
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  8. #8
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    Probably a long shot, but I have a Galfer rotor that varied in thickness by .004". It pulses very noticeably. This may be the problem if your brake has always pulsed. This would not be the problem if it just started.

    It will take a micrometer to measure this small of a variation.

  9. #9
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    they also pulse if the pad is braking on the rotor tines.
    Hell is eternally climbing manzanita trail on your singlespeed.

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