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  1. #1
    mtbr member
    Join Date
    Jul 2013

    New question here. New owner of old Iron Horse 4.2; mx4 on back weak/vibrates

    Just registered & have found the site useful already. Started cheap w/ a well used IH 4.2, then upgraded fork to an XC32TK. Rear brake feels really weak and started to vibrate when applied. Trying to figure out if pads are worn out or if rotor is just dirty. I'll try the alcohol wipe first, then check pads. Not sure if I have to remove them or if you can tell just by pulling wheel?

  2. #2
    B A N N E D
    Join Date
    Apr 2007
    Pull your pads out and check them, it's not hard to do but you'll need to remove the the wheel first.

    Post some photos, there might be a problem with the brake setup.

  3. #3
    mtbr member
    Reputation: crossracer's Avatar
    Join Date
    Jun 2004

    New owner of old Iron Horse 4.2; mx4 on back weak/vibrates

    Some old iron horse bikes had this funky floating brake body. It was a. Mechanical system and the whole system slides back and forth on two rods. If these wear out you get really sloppy breaking.
    Not sure if this is what you have.


  4. #4
    Huckin' trails
    Reputation: David C's Avatar
    Join Date
    May 2011
    From the description of the problem you're giving, I'd say your caliper isn't properly aligned with your rotor, i.e. the pads aren't parallel and perpendicular to the rotor and they will force the rotor to bend and twist under braking, causing the issue of weak braking power and horrible noise and vibrations.

    The Hayes MX4 brake caliper is a mechanical caliper that feature minimal adjustment and tuning capabilities, which enhance the alignment issue when not properly setup. You only have the outboard (outside pad) moving inboard towards the rotor and pushing the rotor against the inboard pad (which is fixed position), so unless your rotor is perfectly straight to a 0.01" lateral tolerance, you will not be able to avoid rotor bending when applying the brakes, because you can't set the inboard pad close enough to the rotor without excessive rubbing.

    At this point, I would assume that both pads did not wear down straight, i.e. they are worn down at an angle, and unless you get new pads, you won't be able to set your caliper properly for minimal rotor deformation. Also, your frame tabs, adaptor, caliper, rear wheel axle, frame drop-outs, hub rotor mounting tab and the rotor itself are all variables into having your caliper perfectly aligned with the rotor. Hayes mechanicals aren't the best out there regarding alignment and tuning, but they offer very strong braking power from their sturdy forged caliper design. I have found this handful of power less desirable than a properly aligned brake setup, because you won't be able to keep a constant braking performance and will always be fighting with your current brake issues.

    The easy fix consist of getting a new brake set, as in Avid BB7 if you want to stay with mechanical disc brakes, which are low-cost, maintenance and very reliable, or to go with some Shimano hydro brakes if you want a more powerful, better modulation brake that will also require a bit more tech knowledge for maintenance and wrenching, but will be easy to setup and provide great braking experience on the trails, at the expense of twice the price of the BB7's.

    I personally run BB7's on my bikes, because it's as good as hydro for my riding and cheaper/more reliable for the weekend warrior rider. But if you're the type of guy who go shred trails 5-7 times a week, you will appreciate the benefits of hydro and they will far outreach the higher price tag over mechanical brakes.

    Pictures would also be very helpful.
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  5. #5
    mtbr member
    Join Date
    Jul 2013
    thanks for the trouble-shooting (all). pads ended up being in good shape (in terms of wear). I loosened the caliper bolts per the instructions, tightened w/ the lever pulled in then adjusted the fixed inner pad. gaps looked good and breaking was better (no vibration) but still weak. Finally took pads out and lightly sanded w/ 220 grit paper. Same for rotor. Cleaned everything w/ alcohol again, then did some repeated hard stops. Finally started to grab & feel decent. Not sure if it will degrade but good for now.

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