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  1. #1
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    2008 Shimano Xt poor modulation/shuddering

    Hey guys, i bought a bike with the new xt stuff on it a few months ago, and the brakes don't feel right.

    The xt disc brakes with a 180/160 centerlock combo don't feel smooth, and although power is awesome, modulation is very poor.

    I read some other posts, and despite the general opinion, when i rode my friend's juicy carbons, modulation was awesome!

    Is there perhaps a bigger pad for shimano that would cover more rotor, or a different compound so i will get better modulation and not get the shaky feedback feeling i am getting now? I want a smooth brake, not a bumpy feeling one.

  2. #2
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    Sounds like something is not right with the setup. Have you checked your rotor alignment? Where your brake tabs faced? Are your rotors aligned properly? Is anything loose? Which pad compound are you running (resin pad may help)?

  3. #3
    Nightriding rules SuperModerator
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    definitely recheck alignment and even pad wear...

  4. #4
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    The pad wear is even, and it is aligned. The bumpy feeling only happens under extreme load, the pads are stock shimano.

  5. #5
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    What rotors are you using? Are you using the same adapter that came with the calipers?
    "Winners never quit. Quitters never win. But those who never win and never quit are idiots."

  6. #6
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    I am using the complete shimano xt setup. The mount is right from shimano, scott and fox both had the tab interface faced. i tried my friend's rear wheel with an avid rotor and it was better, but i still got some feedback from the vents in the rotor.

  7. #7
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    stock pads are metal compound [ in Aus ] & most people I know with XT's have swapped to organic for the symptoms you describe. The metal pads are OK to start but seem to get worse as they wear.

  8. #8
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    Quote Originally Posted by chrismichaels
    I am using the complete shimano xt setup. The mount is right from shimano, scott and fox both had the tab interface faced. i tried my friend's rear wheel with an avid rotor and it was better, but i still got some feedback from the vents in the rotor.
    I had a similar issue with my rear brakes (2008 XT post mount). Front was fine, however the rear was squeeling/vibrating bad. On a long down hill, they would eventually quiet down a bit. Only to start up again with the stopping nill or almost non-existent. I centered the caliper (it was only slightly off) and replaced the Shimano sintered pads with Shimano resin pads. No more noise and the brakes have a nice feel to them - much like my front always had. Note, the brakes were bought used. And the rear pads had some buildup (a white crust around the pads and caliper pistons). I suspect my issue was contaminated pads. I feel pads are a consumable and if in doubt replace them.
    Last edited by phred; 06-20-2008 at 12:18 PM.
    thx, Phred
    I know my parents hated me, because my bath toys were a toaster and a radio.

  9. #9
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    If they are stock, they have sintered pads, which last a long time and are great for mud...but are grabby and noisey when dry.
    Get some organic pads and break them in...and hit an auto parts store and get some brake cleaner and use it to clean your rotors from time to time.

  10. #10
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    I've recently switched to Shimano XTs from Hope M4s and the power is greater and the modulation is a revelation in comparison.

    That said I use the Hope floating sawtooth rotors as the 08 XTs did not come with any rotors.

    It must be a set up issue in my opinion. A great brake set up procedure is Hope's. Look at the videos on their site http://www.hopetech.com as just the finest changes in alignment and piston action make a huge difference to feel and performance.

    Also, look at changing the pads too as by now they will be worn and any alignment changes will not work

  11. #11
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    I've had issues with '08 XTs also.

    I'm not sure what one would have to say to convince others of your mechanical competence, but...

    My previous Avid Mechs, Juicy 7s, and '06 XTs never had these issues. My new XT started out fine, quiet with a grippy metal-on-metal sound that suggested the pads were eating the rotors... in a good way. After a month, both brakes developed a medium-pitch howl that is annoying, but not like the wet-brake squeal or the contaminated-honk. This would occur only at higher speeds; at low speed they're still quiet. I tried new metal pads, which developed the same noise over time. I do not use spray chain lube, and neither my hubs nor fork are leaking any oil. I tried different rotors (degreasing them)and surfaced the pads and broke them in again. Always the same. If you let off the front brake slightly, it vibrates and rattles in a HORRIBLE way. Sounds like loose parts. Bolts tight, skewer tight, hub bearings adjusted, spokes tight. Fork leg not broken. I'm running 203/160.

    Neither brake drags, and I have the caliper centered. The pads contact the rotor at the same time and when they apply, and even if you look very closely, you will see no shifting or torquing of the rotor.

    What else is there? I don't want to run organic pads.

  12. #12
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    Mmmm. Sounds like it could be that Shimano sintered pads have changed for '08?

    I'm on the originals, but as I said the brakes are pretty new and not had the wear needed to get the noise people are finding.

    If I have the problem I'll report back and switch to something like Swiss Stop pads that are getting good feedback for sintered pads.

    My wife runs organic XTR branded pads in her '06 XT calipers and they are great and have been even though she seems to ride around with her brakes on most of the time. and gets through pads fairly quickly. Her experience with the brakes was one of the reasons I swapped to Shimano from Hope.

    A swap to another brand of sintered pads may be worth the cost if everything else is okay. It must be the pads as the brakes seem to be fine at first then worsen.

  13. #13
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    got a qns here, for the shimano xt lever, is the screw head on the lever to adjust the modulation? Im using a formula bianco rite now and building a new bike, tot of using the xt 08 but tried a friends xt brake and it has less modulation compared to mine...can it be adjusted the modulation on the xt?

  14. #14
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    I don't have the new XTs, but I have run shimano metallic pads in my 765s and had similar issues. You might try someone elses pads...

  15. #15
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    I'm experiencing the same thing with my '08 XT (180/180).
    Stock rotors and pads, even wear and they are aligned. Breaking power is alright but modulation is nonexistant.
    Using the front brake is like throwing a freaking anchor out. It got me into trouble a few times on my first trail ride with my new bike today.

    If it doesn't get better after the next 5-10 rides I'll look into those organic pads.
    "The road to success is dotted with the most tempting parking spaces."

  16. #16
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    Having problems with the 08 XTs too.
    The front caliper is fine, no noise, modulation good and good power.
    However the rear caliper with the stock metallic pads has that rough, shuddering feeling and makes an awful howl during hard braking.

    Thought the rear pads were contaminated initially, so I swapped the front and rear pads. The front calipers were quiet, the rear calipers were howling... So pads are not contaminated.

    Switched to another set of wheels with old XT 6 bolt rotors. The shuddering/howling was still there. So not specific to XT Centerlock rotor.

    Swapped the pads with some old Clarks Metallic pads I had from another bike. Very minimal shuddering and softer howling during hard braking. The Clarks pads had a little bit of 'paint' on the back of the pads, so that might have helped to absorb some vibration/noise.

    Tightened all the caliper bolts, put in some loctite. No improvement.

    Gave up and bought the XTR resin pads for the rear. H07S, the one with some 'paint' material on the back of the pads. Problem resolved.

    Still trying to figure out what causing this shuddering/howling.
    The difference between front and rear:
    - Front is on magnesium fork (duh..) with Post Mount (hence without the IS adapter)
    - Rear is on aluminum frame with IS Adapter

    XT Centerlock 160mm rotors front and rear

  17. #17
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    What did Shimano tech say when you called them? If you haven't, you should, and just read what you typed here.

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