They tend to make a tiny bit of a low-tone sound just before you come to a stop if you are lightly applying the brakes....and a tiny bit (also low tone, no squeak/squeal) when backing up and using the brakes. Doesn't bother me, and when stopping harder or if the brakes are warmed up, no sounds. My W126 makes no sounds at all with the same rotors, only the W124 does. The W126 used to squeak a lot when backing up with my old (ATE) rotors, now it has no sound.

On the W124 I have Mintex pads in front and PBR organics in back (I think)....on the W126 I have PBR Advanced Ceramics in Front and PBR organics in back....both cars have awesome brakes.

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