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Thread: shimano XTR rubbing help

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    MoJo Neophyte bikejunkie88's Avatar
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    shimano XTR rubbing help

    I've got '03 xtr disk brakes that are rubbing and have been checked by 3 shops - no one can find anything wrong. Now they're making a squeeking noise. Any one have this problem or know what's wrong? Thanks!

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    MoJo PoLaR BeAr
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    If it's intermittent, maybe the rotor is just out of true?

    I've also seen the brakes rub because the wheel bearings were just a wee bit loose ... check the preload on your axle bearings to ensure there's no slop (don't know if your shop checked that, but it'd be easy to miss).

    Any more description / details of the symptoms?

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    MoJo Neophyte bikejunkie88's Avatar
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    The rubbing is constant and it gets worse as the ride goes on, I am pretty sure thats because the rotor is heating up. I think that the pads may be ajusted to close to the rotor but it takes a shimano tool to do that. Any more theories or comments would be great.

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    Mojo Model of Grace and Tact
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    I rode '03 XTR discs for 6 months and no adjustment I, or any shop made the rubbing go away.
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    Mo betta than Jo SitNSpin's Avatar
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    Quote Originally Posted by bikejunkie88
    I've got '03 xtr disk brakes that are rubbing and have been checked by 3 shops - no one can find anything wrong. Now they're making a squeeking noise. Any one have this problem or know what's wrong? Thanks!
    Huh- that's a good one...
    Most common causes of brake squeal on a disc set up are:

    1) Loose bolts on the caliper
    2) Loose rotor bolts
    3) Dirty, worn , or contaminated pads


    Basically anything that allows vibration can set up harmonics within the assembly. The squeak may mean that the rubbing has finally worn through the pad material.

    If you've been to 3 shops already, I assume that the brake mount tabs have been checked (and milled if needed) to be exactly parallel to the rotor's line of travel? The hub having a bit of slop is a nice point; could be checked. Does the rotor always rub on the same side (ie: inner or outer pad)? Hydraulics usually center themselves on the rotor, but a sticky piston would cause the problem. Since the rubbing gets worse over the course of the ride, it could be that the fluid is heating up and the bleed port is not working properly... Any of this stuff sound new, or have you heard all of this at the myriad shops?

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    MoJo PoLaR BeAr
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    Quote Originally Posted by bikejunkie88
    The rubbing is constant and it gets worse as the ride goes on, I am pretty sure thats because the rotor is heating up. I think that the pads may be ajusted to close to the rotor but it takes a shimano tool to do that. Any more theories or comments would be great.
    Doesn't sound like out of true rotor if it's constant, or bearing or such.

    Don't know if this applies to the XTR's, but is it possible there is TOO MUCH fluid in the system? This could force the pads too far out and would be an easy thing to do wrong either bleeding or setting up the brakes.

    Some real wrench should speak up but I believe it possible ... and should be easy to test ... "just" open the reserviors / master-cylinder at the brake lever and drain a few drops out of them ... easily done with the edge of a paper towel or such ... unsure on how much should be taken out to make a difference but not more than minimum to get a bit of gap between the lid and the top of the fluid. My Magura brakes have a neat rubber hood that does this for me, so all I need do is top off the reservior and merely putting the lid back on sets the fluid level correctly. Sweet stuff.

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    Mo betta than Jo SitNSpin's Avatar
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    Quote Originally Posted by Bear
    Doesn't sound like out of true rotor if it's constant, or bearing or such.

    Don't know if this applies to the XTR's, but is it possible there is TOO MUCH fluid in the system?
    If there were too much fluid in the system, you'd have rubbing AND a very short pull distance at the brake lever. Most brake systems have a diaphragm (like the one you've described on your Maguras) at the reservoir. This helps to keep air bubbles out of the system when replacing the cap of the reservoir. Many brake systems also have a pressure release mechanism that helps to compensate for fluid expansion when it gets heated from lots of brake use.

    I suppose that it is possible to get too much fluid in the system if you were running very worn pads (so the pistons were maxed in the out position), and someone bled the system without pushing the pistons back first.

    Junkie: Have the pads rubbed from day one, or after a specific service point?

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    Mojo Mofo X-Ray's Avatar
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    Quote Originally Posted by Scary Mc
    I rode '03 XTR discs for 6 months and no adjustment I, or any shop made the rubbing go away.
    Scary Mc sold me the Calipers and Shifters and I have not a single problem with them. No rubbing and kickass stopping power. I do ride with a couple of buddies that have the rubbing issues (on 03 XTR) and I'm not sure what they did to fix the problem. I'll check and get back to you!
    Ray

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    MoJo Loco Sugar Mama's Avatar
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    I'm having the same problem. Anyone figure out any solutions? I've had 3-4 wrenches check it out at BSS -- bleed the brakes, add spacers, all kinds of shit, and while they can fix it for a short while, after a few rides, they start rubbing again.

    I'm about to get real pissed.
    "The statistics on sanity are that one out of every four persons is suffering from some sort of mental illness. Think of your three best friends -- if they're okay, then it's you."

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    The William Sapphire of Bike Mechanics
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    in most cases, if bleeding doesn't help to give a more consitant brake feel.....the pistons are likely dirty and need to be cleaned. or rather, the part of the piston that slides in and out of the caliper. if enough grit gets in there (grit being, dirt, dust, sand, mud, brake pad material...) it can make teh brake react oddly. which seems to be the case here.

    this assumes the disc tabs on the frame are faced (especially important with the XTR calipers since there is no "camber" adjustment), the brakes properly bled, new fittings used, the hoses aren't kinked, or damaged, a true rotor, and new pads are used...
    It’s impossible to rate welding/brazing quality by looking at a finished frame joint, even an unpainted one. Files, sandblasting, and a good paint job can take care of that. Such a joint will look stellar unpainted, but won’t last. Yet people all the time look at frames and say, “Nice welding/brazing…” The point isn’t to make you paranoid, just to stop saying things like, “That’s nice welding/brazing,” when you see a painted/unpainted frame. -- Grant Petersen

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    MoJo Loco Sugar Mama's Avatar
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    Thanks for the info. So, from what I gather, there's not a lot I can do myself with these hydraullic brakes. I just took it in to the shop to have the brakes overhauled -- I hope that works.
    "The statistics on sanity are that one out of every four persons is suffering from some sort of mental illness. Think of your three best friends -- if they're okay, then it's you."

  12. #12
    The William Sapphire of Bike Mechanics
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    Sugar Mama...if youhave the bleed kit (which any shop can order for you along with extra olives [martini time!], hose, fluid, bladders, pads and rotors, and shims, you can do just about any of the work yourself. the system is quite simple. all disc systems are.

    the thing is to make time to get the hang of the process. once a step is skipped, or shortcuts used, problems arise.
    It’s impossible to rate welding/brazing quality by looking at a finished frame joint, even an unpainted one. Files, sandblasting, and a good paint job can take care of that. Such a joint will look stellar unpainted, but won’t last. Yet people all the time look at frames and say, “Nice welding/brazing…” The point isn’t to make you paranoid, just to stop saying things like, “That’s nice welding/brazing,” when you see a painted/unpainted frame. -- Grant Petersen

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    MoJo PoLaR BeAr
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    Quote Originally Posted by car!os
    the thing is to make time to get the hang of the process. once a step is skipped, or shortcuts used, problems arise.
    w0rd.

    I was changing the oil in my fork last Sat, and forgot one step ... forgot to drain the damper completely ... so when I put it all back together it was one stiff Fox.

    Can you say "hydraulic lockout" - yes - I thought you could. :P

    Sugar Mama, one of the nice things about Shimano hydros is the use of mineral oil based fluid ... it's not caustic like the Hayes D.O.T. fluid ... so the worst thing that happens is you get a oil mess somewhere. Only bad on the bike if you get it on the brake pads ... which is why they say take the brake pads out before doing a bleed.

    And I side with Carlos, doing this kind of work is NOT difficult, there are a lot of GOOD instructions and pointers out there, and it IS rewarding.

    And the tools are cheap, relatively.


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    boring the Inbred's Avatar
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    i believe Fox forgot to put "drain the damper completely" in the 2002, 2003 manual.

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