XT brake squeal arrrrgggghhhh

Discussion in 'Mountain Bikes' started by dmuhlbaum, Sep 7, 2004.

  1. dmuhlbaum

    dmuhlbaum New Member

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    Hiyah,

    Have retrofitted several-year old XT brakes linear pull (ebay special) onto my ancient Trek 990 (dates to 1989, came with cantilevers). Replaced levers with new LX at same time. New cables, new housings.

    Result: Stops great, but I have insufferable, intractable brake squeal. Tried toeing in, toeing out, no toe (that's what's recommended for parallel-push, I hear), camel toe, you name it. Tried sanding the rims, sanding the pads, Koolstops, Shimanos, Aztecs. Squeal squeal squeal.

    I'd love any ideas on a solution so I can ride this thing without being totally embarassed.

    I'd also be interested to understand more about Why Brakes Squeal? What's really going on? Is it the wheel that vibrates?

    I, and my riding buddies, thank you in advance.

    DM
     
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  2. Juba

    Juba New Member

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    Before I begin I have to say the camel toe comment caused me to blow coffee over my keyboard. But I suppose that will teach me to drink coffee this late in the day...

    The XT V-brakes are well known for their insufferable squealing on the front end of a bike. About the only good news is you are not alone here, and that is a stretch. I have had similar issues with my XT front brakes on my old bike, and basically what you will probably end up going through is just keep trying things until you hit that one thing that finally quiets those brakes up. It sounds like you have hit most of the suggestions already, but here is the order to run through:

    -Resurface the rims with a fine steel wool. I would avoid using sandpaper, it scuffs the rims too much and might contribute to the noise (an old trials biker trick was to heavily sand the rims with course grit sandpaper and smear the rims with a thin layer of tar, which generated amazing stopping power, but squealed like a stuck pig). Resurface the brake pad surface with steel wool, or run the brake pad surface across a sheet of fine grit sandpaper laying on a table.

    -Ensure everything is correctly tightened. If your fork has removable brake bosses, is it possible they have come loose?

    -Play with toe in various degrees.

    -Take the pads off your rear brakes and use them for your front brakes.

    -Purchase new brake shoes. Kool Stops will do the trick for somepeople, most all of the Aztec pads I have ever experienced always seemed to squeal when wet, so I think they are a poor choice for trying to fix a squealing problem. Maybe try a no name pair of brake pads, which tend to be made out of a harder rubber.

    -Reverse your brake pads so the left brake pad is in the right hand side and vice versa. The long side of the brake pads will be facing the wrong end of the bike. ***This goes against the manufacturers recommended installation instructions, so use at your own risk***

    What I ended up having to do to get mine to finally shut up is running the brakeshoes on the reverse sides, with a barely noticable reverse toe out, I can put a piece of paper under the toe'ed end, but I could not slide a business card under it.

    Brake squeal is caused by your brake shoe grabbing and releasing, kind of chattering along the rim. Since the chattering is at such a high rate of oscillation, it ends up sounding like a high-pitched squeal. A brake shoe that does not squeal maintains even friction on the rim.

    Cheers,
    Juba
     
  3. dmuhlbaum

    dmuhlbaum New Member

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    Thanks for the extensive reply:) . Yup, I (and one shop) have tried a number of those already, but not necessarily in that order, and not necessarily in that combination. Will try beating on the thing some more. It takes a very calm mind to approach this, and with two children under 3, I am rarely of said mind.

    One thing I discovered in my online rummagings:

    Item: XTR/XT® M739 V-Brake® Tune-up Kit, available at Speedgoat for $5, . Not very clear what this is. Google not much help. Neither my bike shop, who found it in the catalog and wants $12 a pop. Thinks it's got something to do with the parallel push thing. Might gamble on it.

    DM
     
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