BMW Blog

I've got a 97 M3. Bought it with 68,000 miles. It's up to 76,000 miles now. The brake sensor never did it's thing and the computer never told me to change the brakes but I can hear them grinding in the front. If I look thorough the M-contour rims at the front rotors, it's pretty obvious that they need replacing. There's a nice deep groove left by the pads. But the rear ones aren't so bad. Yes there is a groove, but it's not that deep at all. My question is can I replace the front pads/rotors - and on the rear just the pads?

I'd go ahead and replace the rear rotors as well. OEM rotors don't cost that much and starting with new rotors along with new pads will ensure a good base to properly bed the pads in. New pads on questionable rotors may not bed in correctly and compromise braking performance/balance.

rotors do not necessarily require replacement if micrometer measurement is above mininum thickness required and groves are not excessive.
it depends on who you listen to, as dealers always want to put new parts on your car.
however, if braking symptoms suggest runout caused by bad rotors, then replace fronts even if lightly grooved and above minimum.
it is normal for a lip to develop on outer rotor edge, but should not interfere with new pads.

Well I went back and closely expected the front and rear brakes. I didn't take the wheels off, but with the m-contour rims you can pretty much see right through the "holes". Anyway the REAR brakes still have a solid 1/4" + of pad left, but the fronts have NOTHING! Like maybe a millimeter. So I'm going to replace the front pads/rotors and leave the rear alone.

It's not surprising that the fronts would need replacing first, they're the ones tht do most of the work in stopping the car.