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Thread: Howling BB7s

  1. #1
    I Tried Them ALL... Moderator
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    Howling BB7s

    Why does my front 2005 Avid BB7 howl like a banshee whenever I feather the brakes? The pads are dialed in perfectly, the levers have just the right amount of pull....and the fronts still make this nasty howl- even with the brakes dry. Also, the rotors are brand-new 160mm Avid wavy rotors, and the front pads leave a dark band on the rotor surface. What is this? Are the front pads already worn? Contaminated?

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    I wouldn't worry about rotor discoloration, but can't see what you have either. Are you just now bedding your pads in? Do you have reason to think your pads are contaminated? If so, you might have luck burning out the contaminates. Are your pads glazed? You might try sanding them a bit. Are your rotors warped at all? Details help...
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  3. #3
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    The rotors are perfectly true. The rotor discolorization looks like tiny black bands around the rotor. I was able to remove some of it with alcohol, while spinning the front wheel backwards. I dunno why this somehow worked- but the noise is still there.

  4. #4
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    "The rotor discolorization looks like tiny black bands around the rotor. I was able to remove some of it with alcohol..."

    Sounds like you've got some lube on the rotor/pads, or maybe even picked up some motor oil from car-park puddles. Whatever it is, the streaks indicate contamination of some sort. Start off by cleaning the rotor thoroughly and then checking the pads. Very mild contamination can be removed by sanding the pads on a flat surface to zip the top layer of glaze off. Deeper contamination will probably mean a new set of pads.

    It's worth double checking that your caliper is correctly aligned, too.
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  5. #5
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    In addition to the previous posts, check your caliper alignment. Avids are notorious for being mounting crooked due to the float on the CPS bolts. If the pads are engaging the rotor slightly off perpendicular, might cause the vibs (howling).
    [SIZE=2]Question to a custom frame builder..."So what makes your bikes climb better?"....his answer, "Uh, your legs?"[/SIZE]

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    I also hear that the roundagon rotors are quite noisy and the cleansweeps are quieter, can anyone confirm that? When i feather the rear, it makes a really high pitch noise, feathering the front makes more of a howl.

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    If you have contaminated pads, they can be baked clean. I got lube out of my rears by blasting them with a heat gun for about 15 mins (until the smoke stopped).

  8. #8
    ~Disc~Golf~
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    i dunno if this applies to you, but i also run bb7's.
    i like to keep my bike clean - that being said, i found that too clean can be a problem (for me)
    when i alcohol'd my rotors clean (oils not in pad), i found my rotor howled under light pressure similar to that of a crystal glass - harmonics.
    some dust may actually help.
    infact, if you have the stock bb7 pads, you might try graphite (it also has worked for me).
    When i say graphite i mean the powdered stuff you get from your hardware store; lubes locks etc. Don't go choppin up pencils because they have binders to hold that sh!t together similar to a hard wax - which i think you don't want ...right?
    also on organic pads and any other combination, you might want to shy from this recommendation as i have no experience with those
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  9. #9
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    try to sand that black off the rotor as well.

  10. #10
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    Quote Originally Posted by highdelll
    infact, if you have the stock bb7 pads, you might try graphite (it also has worked for me).
    When i say graphite i mean the powdered stuff you get from your hardware store; lubes locks etc.
    Powdered graphite on my brakes??? I don't think so! This sounds like some of the worst advice I have seen on this forum.

  11. #11
    Rub it............
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    I get a little howl out of my front BB7's once in a while. Its usually when they are first applied when feathering. After they warm up, the noise goes away. I too have the roundagon rotors.

    I'll probably upgrade to the Alligator rotors over the winter and see if that changes anything.

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  13. #13
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    you say the rotors are brand new. give it time.
    When under pressure, your level of performance will sink to your level of preparation.


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  14. #14
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    Check the rotor bolts, they may be loose.

    Mine used to howl like mad too.

  15. #15
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    Quote Originally Posted by gmcttr
    Powdered graphite on my brakes??? I don't think so! This sounds like some of the worst advice I have seen on this forum.
    ok, would you explain the error of my ways? thanks
    Honestly... ahh I give up

  16. #16
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    Quote Originally Posted by highdelll
    ok, would you explain the error of my ways? thanks
    you mentioned yourself that the stuff is used to lube locks. lubricate => reduce friction.

    applying a lubricant to either pad or rotor would reduce friction between the brake pad and rotor.
    When under pressure, your level of performance will sink to your level of preparation.


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  17. #17
    ~Disc~Golf~
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    Quote Originally Posted by rkj__
    you mentioned yourself that the stuff is used to lube locks. lubricate => reduce friction.

    applying a lubricant to either pad or rotor would reduce friction between the brake pad and rotor.
    yeah...it's a lubricant under light pressure. Sintered/semimetallic pads use graphite as part of the friction compound.
    Hey, all i'm sayin' is that it worked FOR ME. It is easily cleaned off if it doesn't provide satisfactory results. OR just don't do it and find another solution - no skin off my back. To someone above saying 'the worst advice" in these forums...really? man...sorry about that.
    Honestly... ahh I give up

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  19. #19
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    This is for frdfanc mostly

    I looked at barkleyfan's link for the Permatex Disc Brake Quiet and wanted to know more, so went to the Permatex site and check out the first bullet point in the product benefit list http://www.permatex.com/documents/td...tive/80077.pdf

    Now, whether this would work for a mountain bike disc brake, anyone try?
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  20. #20
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    Coming from an automotive background of almost 13 years, its possible that it may work.

    But this is a type of application that goes to the backside of the brake pad and not the friction surface. I've had mixed results when applied to automotive brakes.

    Might be worth a try Bikin.

  21. #21
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    [quote=Bikinfoolferlife]This is for frdfanc mostly

    I looked at barkleyfan's link for the Permatex Disc Brake Quiet and wanted to know more, so went to the Permatex site and check out the first bullet point in the product benefit list http://www.permatex.com/documents/td...tive/80077.pdf

    Now, whether this would work for a mountain bike disc brake, anyone try?[/quote


    I tried it. Seemed to work for me. Could have been simply reseating the pads, but I reseated them the same way I had them in there before. Only thing I can think of beides the Permatex that could be different is that perhaps the spring was seated slightly different.The pads should actually reseat the same I would think, judging by the design.

  22. #22
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    I too have just installed some BB7 and they squeal like little pigglets when you twist their tails... Anyway, I just think it's because they're bedding in (I hope), I'll see later if it's a setup noise or I have to do something about it (maybe start bringing an IPod )...

  23. #23
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    Quote Originally Posted by highdelll
    ok, would you explain the error of my ways? thanks
    A few minutes with google turned up this. Improvement of Friction Brake Lining Performance. Basically, it states that graphite is indeed used in brake linings to reduce noise. Ouch...that burns. Bear in mind that this is modified graphite and bonded within the material.

    It does make my initial response seem way overboard. My apologies to you Sir.

    I did find another reason why using graphite on a bicycle may not be the best idea. A part of the Wikipedia article on graphite is as follows.

    "The use of graphite is limited by its tendency to facilitate pitting corrosion in some stainless steels, and to promote galvanic corrosion between dissimilar metals (due to its electrical conductivity). It is also corrosive to aluminium in presence of moisture. For this reason, the US Air Force banned its use as a lubricant in aluminium aircraft [5], and discouraged its use in aluminium-containing automatic weapons [6]. Even graphite pencil marks on aluminium parts may facilitate corrosion [7]."

    I won't be trying it, but if it works for you, great. Again, sorry for the initial response.

  24. #24
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    Avid's organic pads are much quieter, in my experience. They also have a little bit better modulation (but wear quicker, and are less effective when wet).
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  25. #25
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    Quote Originally Posted by frdfandc
    Coming from an automotive background of almost 13 years, its possible that it may work.

    But this is a type of application that goes to the backside of the brake pad and not the friction surface. I've had mixed results when applied to automotive brakes.

    Might be worth a try Bikin.
    Not a problem for my brakes, but just thought you might like the Permatex spelling error...but am curious if the seating interface in bicycle disc brakes might benefit from such a product...
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