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Screaming brakes(8 posts)

Screaming brakesPaulCL
Aug 14, 2002 7:20 AM
OK, maybe not screaming, but very loud.

No problem last week, but this morning my front brakes had such a loud squeal that I hesitated using them. What could be the cause??

I checked the alignment - no problem. The pads touch the rims evenly - no toeing in. I even stopped twice during my morning ride to lightly sandpaper the pads - I had sandpaper in my tube patch kit. The campy pads are no-where near the line for replacement.

Would dirt/oil/grease/road grime on the rim cause this?? In between rides, my bike was on a rack on the back of my mini-van for 700 miles. Help. I can't stand this noise. Thanks. Paul
maybe they should be toed in nmDougSloan
Aug 14, 2002 8:22 AM
Doug is right - toe them in about 1mmOffTheBack
Aug 14, 2002 8:33 AM
That usually does the trick for me.
re: Screaming brakesclintb
Aug 14, 2002 8:42 AM
It would help to know what components you're using and the wheels. Do you have stock brake pads or not?
componentsPaulCL
Aug 14, 2002 9:46 AM
Campy record components with original/stock pads. They have about 7500-8000 miles on them. The rims are Venus Sun Rims - Speedream aerolights. The rims have only about 1000 miles on 'em. Dave replaced them after I found a defect in the original rim. Great service...but I digress.....

I just find this weird. Last Friday - not even a sound from the brakes. Today - they scream. The only things that happened in between was a 700 mile ride on a car rack (rain, grime, etc) and a little bit of wheel truing. I would understand toeing them in a bit if this had been a gradual thing, but its all so sudden and extreme....

Paul
dirt on the rim ?PeterRider
Aug 14, 2002 12:03 PM
you say rain, grime... so maybe some dirt got accumulated on the rim ?

Pierre
componentsclintb
Aug 16, 2002 7:22 AM
Paul,
The first thing I'd do is take off your wheels and get on the pads with a good scrubber sponge. The kind that has Scotch-brite on one side. The green stuff. Scrub them really good with some Dawn detergent and do the same on the rim's braking surface. You want to knock off any glaze that's built up. If that doesn't help, it may be time for a different brand of pads.

Contrary to popular belief, cast and forged aluminum brake arms should NEVER be bent. Bending a forged or cast component will only lead to cracks. Shoot an email to Campy or Shimano to see what their stance on bending a modern caliper arm is. Not a chance they'll tell you it's ok. This practice is a holdover from the old days when those parts were made from steel and had an infinite amount more flex. The pad would hit either leading edge first or totally centered and this caused oscillation in the arms which made the squealing. With that being said, if you do have a problem with the toe-in, get some Kool-Stop pads and holders. http://www.koolstop.com/brakes/brakes.html Look at the "Campi Road Holder". The holders have an eccentic bolt design that allows you to get them lined up absolutely perfect. A side benefit is the Kool-Stop pads are superb performers.
bikepartsusa.com had the Dura type holders, which I've got. They may be able to get the Campy ones as well, but they definately have the pads.

Later
It was gunk on the rimsPaulCL
Aug 16, 2002 8:26 AM
I couldn't see it, but it was there. I scrubbed the rims real well and the squeal was gone. Thanks guys. Paul