Results 1 to 12 of 12
  1. #1
    mtbr member
    Reputation:
    Join Date
    May 2004
    Posts
    448

    XT 775 brake vibration

    Hello,

    I'll give ya the whole story. 08' Stumpjumper 29r (21" size) that came with Juicy 5 brakes. I could not get the rear brake to stop the howling. Tried new pads, new rotor -- did not fix it. Swaped out with a new Juicy 7 - did not fix it. Put my Shimano 4-piston on and it was quiet (disclaimer: pad had slight contact with the rotor that could not be adjusted unless material was removed from the IS mount). Avid brakes were warrentied with the XT's. I put the XT's on and when trying to stop only with the rear brake I get a vibration with a slight howl the resonates through the frame. I have bleed these and adjusted the caliper position to try to resolve but I still am getting the vibration. Granted it is not as bad as the Juicy 5 but we are only talking driveway testing at this point. I have seen the threads on the Avid problems, but non concerning Shimano. Any ideas of what is causing this vibration? I am begining to think the frame is at fault.

    Thanks

  2. #2
    ride hard take risks
    Reputation: dogonfr's Avatar
    Join Date
    Jan 2005
    Posts
    25,589
    If the tabs havent been faced might try that, caliper mount tabs on frame same height, cracked frame, you might just have a frame issue like you suggested. It's a nuisance trying to narrow down what is causing a issue.
    Formotion Products
    http://www.formot

  3. #3
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    3,267
    I had this exact problem. My 4pot XTs with Shimano 180mm rotors made a bad high speed vibration. I tried sanding both pads and rotors, cleaning with alcohol, praying to the MTB gods.Nothing worked.
    UNITL one day I just held on the lever and let the noise go for about 1 minute. I did this several times and then NO MORE noise. Now I can't get it to make the noise again even if I tried. Don't know why it worked but it worked.

  4. #4
    ride hard take risks
    Reputation: dogonfr's Avatar
    Join Date
    Jan 2005
    Posts
    25,589
    Quote Originally Posted by the-one1
    I had this exact problem. My 4pot XTs with Shimano 180mm rotors made a bad high speed vibration. I tried sanding both pads and rotors, cleaning with alcohol, praying to the MTB gods.Nothing worked.
    UNITL one day I just held on the lever and let the noise go for about 1 minute. I did this several times and then NO MORE noise. Now I can't get it to make the noise again even if I tried. Don't know why it worked but it worked.
    Love stories like this throwing reality right out the window.

    I'm being serious because I had a 8" rear rotor over heat and warp as soon as I went to a 6: never had the over heat problem again.
    Formotion Products
    http://www.formot

  5. #5
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    3,267
    Quote Originally Posted by dogonfr
    Love stories like this throwing reality right out the window.

    I'm being serious because I had a 8" rear rotor over heat and warp as soon as I went to a 6: never had the over heat problem again.
    I wouldn't have believed it myself if it didn't work for me. Could have been it got afraid of me and it shut it self up.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jun 2011
    Posts
    9
    Quote Originally Posted by eman2 View Post
    Hello,

    I'll give ya the whole story. 08' Stumpjumper 29r (21" size) that came with Juicy 5 brakes. I could not get the rear brake to stop the howling. Tried new pads, new rotor -- did not fix it. Swaped out with a new Juicy 7 - did not fix it. Put my Shimano 4-piston on and it was quiet (disclaimer: pad had slight contact with the rotor that could not be adjusted unless material was removed from the IS mount). Avid brakes were warrentied with the XT's. I put the XT's on and when trying to stop only with the rear brake I get a vibration with a slight howl the resonates through the frame. I have bleed these and adjusted the caliper position to try to resolve but I still am getting the vibration. Granted it is not as bad as the Juicy 5 but we are only talking driveway testing at this point. I have seen the threads on the Avid problems, but non concerning Shimano. Any ideas of what is causing this vibration? I am begining to think the frame is at fault.

    Thanks
    Did you resolve the situation? What was the solution? I have this going on now...

  7. #7
    Dissolved member
    Reputation: StiHacka's Avatar
    Join Date
    Feb 2012
    Posts
    3,344
    Quote Originally Posted by JollyJumper View Post
    Did you resolve the situation? What was the solution? I have this going on now...
    Me too. I can see the rotor oscillate violently with at least 1/4" amplitude even in very slow speeds. I got a rear 775 slightly used and the pads are not evenly worn so I am going to replace them. I am also replacing a 160mm Avid CS 2 rotor with a Shimano RT-86. The vibration is real bad and not just annoying, it is a passion killer. It feels like it is going to tear the frame apart.

  8. #8
    mtbr member
    Reputation:
    Join Date
    Jun 2011
    Posts
    9
    Quote Originally Posted by StiHacka View Post
    Me too. I can see the rotor oscillate violently with at least 1/4" amplitude even in very slow speeds. I got a rear 775 slightly used and the pads are not evenly worn so I am going to replace them. I am also replacing a 160mm Avid CS 2 rotor with a Shimano RT-86. The vibration is real bad and not just annoying, it is a passion killer. It feels like it is going to tear the frame apart.
    I agree. This is a real buzzkill. I am going to the LBS to see what they think, but I already know they say Im crazy to have a 203 on the back.. It is not my all the time, permanent solution, but it needs to work also because when I go to the Alps again I will prefer to roll like this.. Howver, it did not do this with my old Deore LX brakes. So I can only think it is the brakes, frame, or the wheels, but I see no reason for the wheels to cause this. I guess I should put the old 160 rotor back on to see if this solves the situation. Frame is new as well... 2009 Kona Dawg Deluxe.

    These are the new Deore XT M785, I bought them new. I think I will talk to the seller and see if a swap out is possible as I just bought them and have only ridden them 4 times.

    Im thinking conspiracy theories..... Shimano wouldnt make by design their product so sensitive that it only works with their rotors... Would they? Would they?

  9. #9
    Dissolved member
    Reputation: StiHacka's Avatar
    Join Date
    Feb 2012
    Posts
    3,344
    Quote Originally Posted by JollyJumper View Post
    I agree. This is a real buzzkill. I am going to the LBS to see what they think, but I already know they say Im crazy to have a 203 on the back.. It is not my all the time, permanent solution, but it needs to work also because when I go to the Alps again I will prefer to roll like this.. Howver, it did not do this with my old Deore LX brakes. So I can only think it is the brakes, frame, or the wheels, but I see no reason for the wheels to cause this. I guess I should put the old 160 rotor back on to see if this solves the situation. Frame is new as well... 2009 Kona Dawg Deluxe.

    These are the new Deore XT M785, I bought them new. I think I will talk to the seller and see if a swap out is possible as I just bought them and have only ridden them 4 times.

    Im thinking conspiracy theories..... Shimano wouldnt make by design their product so sensitive that it only works with their rotors... Would they? Would they?
    My frame is a new 456C hardtail with 400 miles on it. I run a 180mm Avid rotor in the front ant a 160mm rotor in the rear. I do not have a slightest problem with the front brake (XT 785). I never had problems with Avid BBDB's with the same frame/rotor either. I suspect the XT pads/calipers are quite picky about rotors. I hope the RT86 will make the problem go away.

  10. #10
    mtbr member
    Reputation:
    Join Date
    May 2004
    Posts
    448

    xt brake vibration on stumpjumper

    Still have the problem. I went to the windcutter rear rotor since people said it worked for the acids. I think it helps some, but the noise and vibration are still there. I might try some thin gasket like material to try to isolate the caliper to the frame.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Jun 2011
    Posts
    9
    I still have problems too. I switched to an old Shimano 160 rotor I have, and it got better, but didnt stop. I have been talking to Kona and they are giving me free new dropouts for the rear end. Kona has unique dropouts I would say...

    I seriously think however that the problem is with the brake pads - it seems shimano has manufactured SH-T this time, at least in the resin pads that come stock. Rose-versand customer service was horrible - when I asked if anyone else has complained they said no directly. THen they said, and I quote, "you are free to send them back to us so we can prove there is nothing wrong with them and then we will send your brakes back to you." NICE eh? They also told me to change the pads, and I replied that they could send me some since they sold me the crap ones from the start - he laughed at me. Internet buying is what it is sometimes, but still: Rose-Versand is a major seller across Europe, based in Germany. I was on the other hand lucky to buy these XT 785s for only 150, but deal or not I expect it all to function correctly, whatever I buy for whatever price, and that is a good thing about the consumer protection laws in Europe - EU law says 2 years on basically everything. so the standard 90 day warranty that used to be the norm in USA a laugh.

    I have ordered at a good price from my LBS Ice tech rotors for front and back, and plan to put on the ice-tech pads as well.

    I switched the front with the back pads and noticed that the front was eating them at an angle, great news too. I rode down one tiny asphalt hill and did not hear the rumble on my way home from the bike shop. Tomorrow I will test them when we go for a ride, and also Monday is time for some mountainclimbing (over 1000 meters....) followed by some kick but singletrack in La Pedriza park outside Madrid.

    bottom line: Kona service good, My LBS (trek shop) good. everything else is debatable at this point. I think the brakes/pads may be the cause at this point.

    Problems or not, I am a lucky duck to be living in Spain :=)

  12. #12
    Dissolved member
    Reputation: StiHacka's Avatar
    Join Date
    Feb 2012
    Posts
    3,344
    I have just installed a new Ice tech rotor and new resin pads and bedded them in and the problem seems to be gone, I am keeping my fingers crossed. The difference is big, there is no way the ice tech rotor with its massive aluminum carrier can vibrate as violently as the thin Avid rotor.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •