My disk brakes won't stop screaching

[dugthet]

I bought a specialised hardrock 2008 series in september of 07, and at most 2 weeks afterwards when ever i went on trails the front brake would screach like hell, as i used it more it'd screech more often. Now the front and back brakes screech when i cycle along a flat road and brake.
Both brakes are avid ball bearing 5's
can someone please give me some idea of what's wrong and what to do about it?
thanks

 

[GrumpyGregry]

don't set them up according to the avid instructions but try this instead. worked on mine a treat but I still upgraded to BB7's first chance I got, though the BB5's are going on a drop bar singlespeed mtb I'm building!

 

[dugthet]

hmm

i tried that and still the screeching occurs, but like everything else ive tried it isnt there until ive used the brakes once, then the second time it comes back.
thanks anyway

 

[byegad]

I have BB5s on my Ketttwiesel and they squeal in the wet no matter what. The lighter they're applied the worse they get although they squeal under VERY heavy braking too!

I regard it as an extra warning sytem, if I'm braking then I want people to know I'm there.

 

[Yellow Fang]

I had a problem with my rear disc screaching. According to the LBS owner, you're supposed to wipe them clean using a special cleaning spray. That didn't work. Then he got a special facing tool to make sure the brake mounts were dead straight. That didn't work neither. Then he said he just didn't know what was wrong with them. However then it stopped screaching. Either they eventually bedded in properly, or just taking the wheel off and putting it on again did the trick.

 

[Angelfishsolo]

+1. This happens with car brakes as well. After a while the problem just goes away. The screeching is quite freaky but far better in my books than grinding.

I had a problem with my rear disc screaching. According to the LBS owner, you're supposed to wipe them clean using a special cleaning spray. That didn't work. Then he got a special facing tool to make sure the brake mounts were dead straight. That didn't work neither. Then he said he just didn't know what was wrong with them. However then it stopped screaching. Either they eventually bedded in properly, or just taking the wheel off and putting it on again did the trick.

 

[GrumpyGregry]

its often to do with high frequency vibrations which are normally above our hearing threshold. when the mass of the disc pad changes the screech continues but becomes inaudible. a fat blob of coppaslip ?spelling? used sort it whenever I had to put new pads on my Laverda. (Italian motorbike)

 

[Globalti]

Your pads are contaminated with brake fluid. Clean the discs with alcohol and put the pads in the dishwasher.

 

[arallsopp]

Your pads are contaminated with brake fluid. Clean the discs with alcohol and put the pads in the dishwasher.

Must be awful clumsy to get brake fluid on a set of mechanical brakes. No wonder they screech. I got a similar noise when I bent the rear derailleur on my fixie...

 

[GrumpyGregry]

Your pads are contaminated with brake fluid. Clean the discs with alcohol and put the pads in the dishwasher.

nope. only does it with brand new pads and cleaning the disc makes not a jota (boom boom) difference. New pads and new floaters were a sound for sore ears for about the first 50 miles....

bugger I'm in the wrong forum - these blokes don't have triples in the way I do!