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  1. #1
    40a
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    Formula: annoying pad rattle, help

    I have 08 Formula Megas. They work perfectly. However, anytime the bike gets bounced to the side it causes the brake pads to slap the rotor, causing an annoying vibration sound. Same deal when I lean to one side (like when climbing out of the saddle)-- the fork flexes just enough to cause the pad to rattle against the rotor.

    I've tried all kinds of things to fix it. The calipers have been positioned and repositioned. I've tried running the pads close and far. Tried organic and sm pads. And I've tried more and less retention spring pressure. I even tried using 2 of the metal springs together to double the retention pressure (conceivably). The only way to prevent the pads from vibrating against the rotor is to allign the caliper so that one pad is dragging to dampen the rotor vibe... but this only lasts until the pads wear enough to create a gap.

    Does anyone have ideas on how to sort this out?
    Last edited by 40a; 04-17-2010 at 02:05 PM.
    cosmic slop.

  2. #2
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    Buy a stiffer frame and /or fork

    No, seriously - the brake rubbing is only the symptom......the cause (and cure) is in the flex of the chassis.
    Rimmer - "There's an old human saying - if you talk garbage, expect pain"

  3. #3
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    You could try switching to a slightly thinner rotor, but that too is just a band aid. It appears to me that you are dealing with frame/fork flex

    If this is on both wheels
    Get the both tension checked or re-tensioned.

    Also, check the bushings in your fork to make sure they are not too worn and cause unusual flex.

    Check your rear linkage to make sure it's tight and has no play.

    Also check your wheel hubs to make sure they have not play.

    .
    Lead by my Lefty............... right down the trail, no brakes.

  4. #4
    40a
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    You won't really get much stiffer than a DMR Trailblade jump fork on a Sinister Ridge with fat boxed stays. Yes, there's still some flex in the fork.. but that's not the real issue. Upon side type impact, the pads *whip* against rotor... as if they're not retained strongly enough to the piston. You can create the vibration just by hitting the frame or fork with your fist; that's not a flex issue.

    Both King hubs are sweet.. and the wheels are perfectly tensioned. I'd worry about heat dissapation with a thinner rotor.
    cosmic slop.

  5. #5
    40a
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    and i doubt that wheel tension would have effect on hub/rotor flex. I sent Formula an email... I'll see what they have to say.
    cosmic slop.

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