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heckler
May 21st, 2007, 09:14 PM
OK, I brought my bike in to my LBS (no names as I am not happy and they are NEMBA sponsors) for a fork rebuild. Long long story short when I got it back the front disc brake howls. It didn't do that before it went in. Yeah, yeah, bring it back. I could but I don't want to.

These are Avid mech brakes. I assumed the tech had gotten grease on the rotor. I cleaned the rotor and pulled the pads and scrubbed then down with dish detergent and a scotchbrite. They were pretty bad. Still howling. I realigned the brakes (loosen the bolts,, grab the brake, tighten the bolts). No help. any ideas? I would have thought the cleaning would have solved the problem. The last time this happened I replaced the pads but I don't really want to do that as this job has already cost way too much.
TIA.

chris
Slappy
May 22nd, 2007, 10:31 AM
Pads don't seem to clean up well in my experience - probably have to bite the bullet and replace 'em. :(
heckler
May 22nd, 2007, 11:06 AM
Yeah, I was afraid you would say that. That was pretty much my experience as well. Sucks since I just dropped so much coin on the fork. Serves me right for not stripping the bike down and just bringing in the fork. Live and learn. Just adds to the pain. No one said riding was cheap though.

Thanks
mhaskell
May 22nd, 2007, 11:31 AM
Yeah, I was afraid you would say that. That was pretty much my experience as well. Sucks since I just dropped so much coin on the fork. Serves me right for not stripping the bike down and just bringing in the fork. Live and learn. Just adds to the pain. No one said riding was cheap though.

Thanks

In my mx experience you can sand down the pads a bit and hit them with brake clean to remove the top surface contamination.

Not sure if it works with bike pads however, I've still got awful V brakes. :(
S2RT
May 22nd, 2007, 11:48 AM
In my mx experience you can sand down the pads a bit and hit them with brake clean to remove the top surface contamination.


I tried sanding with a super fine grit, and adjusting caliper positions (loosen bolts/squeeze brakes/retighten bolts), and that got rid of the noise for me. Getting the calipers adjusted took a few tries and was tricky/frustrating.
heckler
May 23rd, 2007, 08:14 PM
Well, I should have some time tomorrow to play with it a bit. And then on Friday the new pads are arriving. If I get it quiet, great, I have spare pads. If not? Well, replacing them worked the last time I got grease on them.
S2RT
May 23rd, 2007, 09:21 PM
You might try brake pad lube on the back to reduce vibration noise. If you need a small amount, AutoZone has single job packets they sell at the register for $1.
Redsars
May 27th, 2007, 11:22 PM
I had a similar experience, I had my rear shock rebuilt under warranty, and when I got the bike back, the brakes had lost their stopping power and made all sorts of noise. I tried sanding, brake cleaner, everything to no avail.

Only cure in the end was new pads, which cost me as the delaer denied any possibility of getting oil or grease on the rotors
splangy
May 28th, 2007, 01:51 PM
You might try brake pad lube on the back to reduce vibration noise. If you need a small amount, AutoZone has single job packets they sell at the register for $1.

Bad idea. Bicycle brakes don't squeal from lack of lubrication on the back of the pads like cars do. The squealing is coming from the contaminated surface of the pad in contact with the rotor. Greasing the back of the pads with that stuff will more than likely just lead to further contaminaation.