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Thread: HorrificHOWL

  1. #1
    SRR
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    HorrificHOWL

    I've been relying on good V-brakes and ceramic rims for years without any complaints, riding aggressively on Washington trails that are wet for much of the year. The only time I've noticed any shortcoming with this setup is when it is wet and very cold at the same time or when conditions are wet and the rims are old. So, since we've had a colder/wetter winter than average so far this year and my rims are starting to look polished, I decided to spring for a trial BB7 up front on one bike (my dedicated winter rig) for only a slightly larger investment than a fresh ceramic wheel. Result: despite fastidious care in setup, a HOWL is generated when it's wet that can be heard three terrain features away !!! Yeah, I understand a certain amount of squeal is normal with most disk brakes, especially when it's wet, but I'd rather plunge over a cliff at the next switchback than have to listen to this every time I reach for the lever! Plus, although the brakes work more consistently stopping-wise when it's wet, they're not any more powerful than my V-brakes are on a fresh ceramic wheelset, and seem even less so when conditions are dry. Anyway, since the conditions where V-brakes/ceramics fail in my experience are rare and momentary, I'm almost tempted to rip off my new parts and revert to the old, which will waste a good chunk of change, since I'll still need to replace that old, tired ceramic rim. I can't tolerate the howl under wet conditions, particularly as they are precisely the conditions which the disk was intended to target -- otherwise, braking is simply not an issue for me. So, since I don't like to twiddle much or experiment -- or fix what ain't broke -- or even read the magazines any longer, my question to you disk users out there is: what should I try next before resorting to drastic measures (that is, putting it all on eBay)? I've cleaned the rotor, lightly re-surfaced it, applied disc brake goo behind the pads, set up everything strictly IAW manufacturer's directions, and everything should be worn-in by now.

    So give me some ideas, so that I can be confident that I've done all I could before I throw it all away and order a new ceramic wheelset -- or let me know that it's a problem I must live with, so that I can do that right away. I've searched elsewhere already and that hasn't helped.

    Last edited by SRR; 02-09-2007 at 12:55 PM.

  2. #2
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    No experience with bb7's, but my shimano hydros, squeal when wet, but are much quieter, and better with koolstops pads.

    Just bought some new ones too swap up the stock XTR's that I just upgraded, cause the rear is squealing in the snow.

  3. #3
    SRR
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    Thanks, that's my first instinct too, particularly as I'd moved the brake to a rigid fork after running it briefly on a suspension fork, which exploded on me. There's some chance the pads got contaminated then from some oil but I don't think so. Fresh pads would settle the issue and allow me to start over. Some riders have indicated that wet weather pads are more inclined to squeal than dry ones. One guy I know runs a wet pad on one side and a dry one on the other and swears he's never had any squeal. But damn if I'm gonna buy two complete sets of pads just to try that! It's frustrating going through this nut roll again -- part of the reason I've resisted disks for so long -- because I've been through it before with rim brakes and ultimately emerged with a combination I was happy with (V's/ceramics). Now I feel I'm starting all over again with no really distinct advantage and certainly less patience.

  4. #4
    Are you talking to me?
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    Have the Tabs faced.

    Most good shops are going to have a tab facing tool, to make sure the caliper is straight.

    it is an IS tabbed fork, right? not Manitou's post mount?
    gfy

  5. #5
    SRR
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    Yup, it's IS alright. Don't imagine it's a facing issue, given the way the BB7 is self-aligning. It is however a 6-bolt rotor on a center lock hub, via an adaptor, so I decided to eliminate that potential culprit by applying some disk goo to the rotor/adaptor interface and the splines on the hub also. In the process, I discovered a directional arrow on the rotor indicating that I had it the wrong way, so I flipped it. More to follow when I get a chance to see if any of this made a difference.

  6. #6
    SRR
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    Same-o

    No change, even when it's dry now -- howl is only slightly less horrific under hard braking.

    Oh, well, unless I got lucky somehow -- and quick -- this gear is going to the discard pile and the V's are returning, tired rim and all. At least when I can't stop as well, I can concentrate on what I'm trying to accomplish. This disk is just as likely to hurl me into the trees because it's so distracting that I forget what I'm trying to do !!!

  7. #7
    Meh.
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    The BB7 is not self-alligning. It has the CPS washers which are orbital and can make up for small flaws or misallignments.

    As for the pads, if you got oil or any sort of contaminant on them. They are absolutely trashed. You can try to burn the contaminants out, but it will not be 100% again.

    Clean rotors with alcohol.

    Take the time to bed the pads and rotors correctly.

  8. #8
    neutiquam erro
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    I've set up a few sets of BB7s now, and don't have any problems with howls (outside of the normal break-in period). Perhaps I am just extrememly lucky. And, I'm sure that because I've now made the claim publicly, the MTB gods will punish me with howls on my next ride...

    I digress. The only thing I can offer is that there's some trial-and-error and patience required with the BB7 set up. I don't doubt that you did a good job of carefully following the set up instructions, but I had to go through the set up a couple of times to get it dialed right. Set it up in the stand, take 'er for a spin around the parking lot, tweak, put her back in the stand to look at clearances, re-adjust, and so on. It takes some time up front to do that process, but it's been well worth it for me. Simply doing the set-up sequence once (even very thoroughly by-the-book) without re-attacking after a ride or two guaranteed me howls.

    Hope this may help; keep tweaking and be patient. They can take a while to break in.

    Cheers, Chris

  9. #9
    SRR
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    What you describe is what I've been doing, so I guess I'm the unlucky one. I'll just have to keep shaking my can of chicken bones and give it a little more time, I suppose. At least this, along with what XSL_WiLL had to say a moment ago, confirms that my situation is abnormal and that I should be able to rectify it somehow -- eventually. I don't expect to eliminate every occasional squeal but this howling has got to be curable, which is what you guys seem to confirm. That's heartening. I'll give it a little more time/tweaking first and then perhaps start over with new pads, if that doesn't work. Anyway, thanks for the encouragement.


  10. #10
    SRR
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    Quote Originally Posted by XSL_WiLL
    As for the pads, if you got oil or any sort of contaminant on them. They are absolutely trashed. You can try to burn the contaminants out, but it will not be 100% again.
    I'm curious, if pads get contaminated how does this exhibit itself, reduced stopping power, noise or both? My stopping power is good, although there's some chatter at the extreme end when it's wet, hill is vertical, and I'm attempting to come to a complete stop quickly. But I expect that's normal. I wonder, is there any truth to wet condition pads tending to be noisier (in the wet) than dry, or vice versa? This would be nice to know, if I end up ordering some new ones.

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