Disc Brake Noise Bothering You?
 

This weekend I tried something that I have not heard mentioned here. I removed my Shimano L05A-RF pads, taped up the resin friction material, and sprayed the back with CRC Disc Brake Quiet. I let dry overnight before reinstalling. Man, are these quiet!!!

I have not put them through their paces or a wet ride yet. Maybe worth a try if all else fails. Cheap and quick.

so basically...
 

a thin buffer between pistons and the back of the pad?

Yeah sounds like it. Which kinda makes sense because thats what you need to do for car brakes not to squeel.

Interestingly enough, I have been experiencing front brake rub after heavy braking on my SRAM Red discs. Last night, I put the bike up on the stand, pulled the pads, and cleaned around the pistons and the backs of the pads. The gap between the pads with the wheel removed is slightly larger using a feeler gage. I guess it's something I'll need to pay attention to.

Update if this works in wet! :cool:

Yes. This is the theory. Its like a silicone rubber on the backing that keeps the pad and rotor from harmonizing.