ahhh! so i had time to change my rear brake pads tonight. they were kind of a B but i have the piston tool so it made it seem easy. threw on the hawk ceramics and had em back on the rotors with some trouble but finally got em on. i had the whole caliper assembly off. swapped pads, turned pistons and put em back on. my guess is warped rotors being the main problem....both rears scratch really bad going down the road. did my heat cycles for the brakes..stopping and going and so on and it seemed to get worse. then something really mind boggling happened. when i got home with it....i put her away in the garage, scoffed and stomped my way to the house door. well as i got out i hear a really weird noise...kind of like the car(rear end of the car) was settling or something ??? it sounded like the pistons were pushing on the calipers to engage park or something and it wouldnt. as if it were gripping the pads hard then letting go...then gripping then letting go. i dunno....really weird. did it for about 3 min then quit. this sound like anything you all have heard? is there any way to install your calipers and brake pads completely wrong? im stumped. almost afraid to drive it now. let me know asap...im gonna hit the hay and check this thread in the morning. a complete set of rear brake pad changing instructions on a s197 would be great too. thanks!