Here I was trying to track down a subtle rattle from the right-front over the last few months, thinking it was suspension-related.
Coarse surfaces, sharp-edge bumps - rattle, rattle. Bloody annoying!
And today, I realised that light braking almost eliminates the noise. What a numpty
Evora Brake Pad Rattle - YouTube
It's coming apart tomorrow to see what's up with it.
Brake pad rattle can be caused by several things:
1. Knock Back, from a warped or irregular brake rotor/disc, that bumps the pads back as it rotates. Check your rotor run out with a dial indicator, and if it is over .005"-.010", turn or replace the rotors.
2. Suck Back, from sticking seals on the caliper pistons. With the car sitting still, push the brake pedal and release it, then check if the pads still rattle. The cure is greasing the piston seals with caliper specific seal grease.
3. Pad taper, caused by the caliper flexing open under extreme pressure and heat conditions, usually associated with track use. The pads will be worn at the heals, near the outer diameter, and will rattle more there, and little at the edge near the center hub. The solution is to replace the pads, or sand them to even thickness all across the pad surface if they are not too worn. Then, get more air to the discs, and consider changing to a higher heat rated pad.