How to stop Avid high pitch whistling/squealing?- Mtbr.com
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  1. #1
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    How to stop Avid high pitch whistling/squealing?

    Hello again, I posted questions about Juicy Carbon pulsing about a year ago, and ended up getting new rotors to solve that problem. Today I'm curious what causes the high pitched, constant whistling that occurs during certain brake pressures. I've searched and there are many posts about Juicy noises, but there is so much differing terminology that I wanted to pinpoint my problem with a new thread. I am NOT referring to pulsing or turkey gobble.

    This whistling is happening on 2 sets of Avid brakes for me....on the rear of my BRAND NEW Avid Codes, and on the front of my 1 year old Carbons. The fact that it's on 2 entirely different type of brake, which have 2 different kinds of pads(I'm using galfer reds on the carbons) tells me that this is most likely a setup issue rather than a rotor or pad type issue. I have read all about the differing methods of how to tighten the caliper while rotating the wheel, feathering the brake, and on and on and on...but will this work on a system that is already making noise? Or do I have to start with fresh pads? Any input would be greatly appreciated.

    ALSO....anybody have any idea how to get more fluid into the Avid systems? I like a VERY instant pad engagement and always follow the bleed instructions to the tee, but never get the super instant contact I'm looking for. I've called Avid and they said to dial the pad contact knob "in" for quicker contact, which is completely backwards based on what I feel. The more I dial it "in" the closer the lever gets to the handlebar before stopping. One more note, I do NOT push my pistons back into their bores before bleeding since I believe leaving them as-is leaves more room for fluid to aid in quick engagement. Does that make sense?

    Thanks!

  2. #2
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    You don't need new pads, just resurface them by sanding in a figure 8 pattern. You can try beveling the leading and trailing edges a little bit too.

    You're purposely overfilling the system. Don't take it too far, you want the system to be able to accomodate fluid expansion. The bleed instructions tell you to bleed with the knob in full out position. You can bleed with the adjuster set in some.

    Describe the whistling? Is it like a metal on metal sound? Or what? Just play around with it. Make sure it's grabbing the rotor correctly. Make sure that the rotor is scraping the caliper or adapter or anything. And just try a couple of the methods mentioned for centering the calipers.

  3. #3
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    Quote Originally Posted by XSL_WiLL
    You don't need new pads, just resurface them by sanding in a figure 8 pattern. You can try beveling the leading and trailing edges a little bit too.

    You're purposely overfilling the system. Don't take it too far, you want the system to be able to accomodate fluid expansion. The bleed instructions tell you to bleed with the knob in full out position. You can bleed with the adjuster set in some.

    Describe the whistling? Is it like a metal on metal sound? Or what? Just play around with it. Make sure it's grabbing the rotor correctly. Make sure that the rotor is scraping the caliper or adapter or anything. And just try a couple of the methods mentioned for centering the calipers.
    I have found that sanding the pads and cleaning the rotors every week or so keeps the Avids dead silent.

  4. #4
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    The problem is that some people take cleaning the brakes too far. You have to let the pads bed in. I do not clean my rotors unless I get something on them.

  5. #5
    Bodhisattva
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    DB,

    I've read a variety of possible solutions to the Juicy squeal problem.

    What worked for me was switching to Galfer Red pads. Did that when I got my J7's two years ago and they've been squeal free ever since.

    YMMV

  6. #6
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    Quote Originally Posted by XSL_WiLL
    The problem is that some people take cleaning the brakes too far. You have to let the pads bed in. I do not clean my rotors unless I get something on them.
    I hear ya. Maybe I made myself sound a little ambitious. I generally sand my pads everyother week and clean the rotors less often. My brakes let me know when that time is.

  7. #7
    Bodhisattva
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    Quote Originally Posted by be350ka
    I generally sand my pads everyother week


    Dang. The only time I sand my pads is if I change a rotor (which occurs rarely, if ever) or if I suspect a loss of power do to glazing (also rare).

  8. #8
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    I think that most of it still has to do with set up and break-in. I've been running the stock Avid compound since I got them over a year ago. I do run them with Hayes rotors and Hayes adapters. I have run them with Avid rotors, Hope 2 piece rotors, and some laser cut aluminum rotors. I have had ONE problem with stuttering with a Hayes rotor. It was a combination of a hot spotted (defective) rotor and an unevenly worn pad.

  9. #9
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    I noticed my would squeel if I ride through muck.

    I got rid of the squeel by cleaning the rotors and pads. I remove the pad and clean them with a strong solvent like brake cleaner/carb cleaner/acetone etc... I would then apply a very thin film of antisieze on the pads backing which touches the pistons of the caliper/body of caliper. Being very careful to make sure you dont' put any on the pad surface that touches the rotor.

    Then I would put some solvent onto a clean rag/paper towel and ripe the rotors clean.

    If your automobile ever gets squeeling brake pads. Take the brake pads out and put some antiseize onto the back of the pads. Ofcourse unless the squeel is the indicators telling you, you need a brake job bad.

  10. #10
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    Eh... Or you could use squeel-stop. Squeel stop kinda dries on and "glues" the pad in place. Antiseize is more the stuff I put on the bolts and slider pins.

  11. #11
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    Shrieking brakes

    I have Juicy 5's on two bikes and have experienced brake noise a couple of times. I clean my rotors about every other ride with alcohol and a clean rag. It's amazing how much stuff comes off. Make sure your calipers are alligned properly too. I switched to green pads made by EBC or someting like that. I have not had any noise since. As for rotors, I have the wavey ones everyone complains about. They have been pulse and all around trouble free for me.

  12. #12
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    Quote Originally Posted by XSL_WiLL
    Describe the whistling? Is it like a metal on metal sound? Or what? Just play around with it. Make sure it's grabbing the rotor correctly. Make sure that the rotor is scraping the caliper or adapter or anything. And just try a couple of the methods mentioned for centering the calipers.
    It's a constant high pitched sound that happens at a certain point in the lever throw. The pitch of the sound never waivers and does not resemble metal to metal contact. The fact that the sound goes away once I get deeper into the lever throw also tells me there is no inappropriate contact. It doesn't matter how fast I'm going, or how long the descent is, so I don't think temperature is a factor. Sanding the pads sounds like a good idea, since I almost feel like the pads might of somehow become concave, creating a pocket for the whistling/squealing to originate.

  13. #13
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    Quote Originally Posted by The Squeaky Wheel


    Dang. The only time I sand my pads is if I change a rotor (which occurs rarely, if ever) or if I suspect a loss of power do to glazing (also rare).
    I guess you could call it preventive maint. I occasionally get the turkey call deal with my 7s and find it far less frustrating to do the sanding than put up with that garbage.

  14. #14
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    Quote Originally Posted by The Squeaky Wheel
    or if I suspect a loss of power do to glazing (also rare).
    I have been getting some glazing recently that seems far more frequent than I remember in the past. What could be causing this?

  15. #15
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    As an interesting side note re: lever feel...
    I have a Braking front rotor on my Juicy Carbons and the lever contact point is considerably better than withthe stock rotor. They're 1.5mm thick rotors, so I guess there's less lever throw until the pads hit the rotor.
    As a plus side, the Braking is completely silent with Kool Stop pads (-:

  16. #16
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    DB, try a completely organic pad compound instead of the semi-metallic Avid and Galfer pads. I really like the new Avid organics for J7s.

    As always, check for sticky pistons, rotor deflection and uneven pad wear. If you do have one pad worn more than the other, don't try to recenter the caliper until you get some new pads in (at least for the recentering process).

    I agree with you on the lever throw issues. You could try to bleed them with no pads in (but something to allow you to pry the pistons back when done), but that may be going too far into overfilling.

    op
    www.msmtb.org - Mississippi Mountain Biking

  17. #17
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    Bleeding

    Bleeding my Juicy 5's was a long and drawn out process. I actually did it about 3 times till I got it right. I think the most important element of bleeding these brakes is a lot of patience. Waiting for the tiniest of bubbles to float to the top of the bottle is key. It looks like the Juicy 7's are easier because of the different reservoir design. I would think the 7's would be quicker bleed.

  18. #18
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    Quote Originally Posted by ohpossum
    DB, try a completely organic pad compound instead of the semi-metallic Avid and Galfer pads. I really like the new Avid organics for J7s.

    As always, check for sticky pistons, rotor deflection and uneven pad wear. If you do have one pad worn more than the other, don't try to recenter the caliper until you get some new pads in (at least for the recentering process).

    I agree with you on the lever throw issues. You could try to bleed them with no pads in (but something to allow you to pry the pistons back when done), but that may be going too far into overfilling.

    op
    Good ideas. I totally forgot that I used to bleed my Hayes with no rotors in and pump them til their closer to get a quicker stop, since their pistons retract so damn far.

  19. #19
    Bodhisattva
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    Quote Originally Posted by 67degrees
    Bleeding my Juicy 5's was a long and drawn out process. I actually did it about 3 times till I got it right. I think the most important element of bleeding these brakes is a lot of patience. Waiting for the tiniest of bubbles to float to the top of the bottle is key. It looks like the Juicy 7's are easier because of the different reservoir design. I would think the 7's would be quicker bleed.
    Bleeding the J7's is a piece of cake. I've never bled J5's.

  20. #20
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    Quote Originally Posted by be350ka
    I have been getting some glazing recently that seems far more frequent than I remember in the past. What could be causing this?
    Dragging your brakes too much?
    Pad compound?

    Using either a 7" or 8" rotor up front on my J7 and a 6" in the rear I rarely, if ever, get glazing. I'm using Avid OEM rotors and Galfer red pads.

  21. #21
    Bodhisattva
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    It's easy to overfill the J7's & I did it one time accidentally.

    I recommend bleeding with a rotor of spacer device in place. Make sure the pad contact adjustment knob is all the way out when bleeding.

  22. #22
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    Quick update on getting quicker stops

    I pumped the brakes with the wheel/rotor out which brought the pads closer together, then I bled the brakes. This worked GREAT for getting a much quicker engagement. In fact, it worked so great that I'm going to have to go back and separate the pads with a flathead screwdriver and the lever bleed screw uninstalled in order to get rub-free wheel rotation.

    I still haven't sanded my pads to get rid of the whistling. That's next.

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