Join Date: Jun 2001
Location: Bergerac, France
What pads/disks are you using now?
Alot of the time when you use 'performance' pads, once they get hot their coefficient of friction goes up, so you don't need to press the brakes as hard to get the retardation you need. Because the pads are effectively loose in the caliper and not squeezed between disk/brake piston, they are free to vibrate, which they do, causing the noise.
The most common way to try and cure this is to slap loads of copperslip on the REAR of the pad to effectively 'stick' it to the caliper. I'll repeat that, the REAR of the pad.
The other way is to file a chamfer onto the leading edge of the pad.
Given that pads these days wear the disks out in record time, I would say you were wasting your time by sandpapering the disk faces. However if you do want to try that as well, jack one side of the front of the car up, whip off the wheel, stick it in gear and just come off the clutch. If you have a LSD make sure both wheels are off the ground.