Contour Enthusiasts Group Archives Forums Modifications Brakes 2!! busted brake rotors

Driving home on a 2 lane highway last night when I got stuck behind a line of 6 slow cars. I pull out to pass and #3 pulls out right in front of me, then #2 pulls out and almost pushes #3 into the ditch (I guess theydon't know to check their mirror 1st, idiots). Anyways I stand on the brakes and avoid any problems, BUT I start hearing ginding from the front end and have a very soft pedal. Turns out I cracked the left front rotor and sheared the mounting area off the right front. Both were Autostop cross-drilled, put em on last Sept, maybe have 15k on them. Fortunatley I had the old OEM rotors to switch with.

Any ideas why that would happen, I've done harder stops on the track?

Were the brakes cold (i.e. cold ambient temp and long time since last braking)? I bet at the track your brakes are warm and stay warm, but the thermal shock of hitting them hard from cold made the rotors expand fast enough to propogate some microcracks introduced during the drilling process. But you say you have a full winter on them.