I have an 88 r 30. westeren 6/8.5 drop. I cant get the calipers to stop rattling. I have put new slides and spring shims on it, but a few trips later, they rattle again. I HATE rattles.
CRC makes a pad quiteing agent you can try, its kinda a orange color glue stuff. we use it a lot on race cars when we are testing to get the pads off the rotors and reduce drag, we use it between the pad and the piston
Although I'm a noob here, I have been a mechanic and racer for years. We use a product made by NAPA called Sil-Glide. It is a non-melting grease that you can lube slides with as well as the back of pads (obviously non-friction side of pad). This works better than brake bad "shims" that can themselves cause rattles and squeaks).