so i bought stoptech 355mm BBK (1 piece rotor) in May. Since then, i've done 4 track days and 1 autocross. After 3 track day, I saw some cracks on the surface. My friend's stoptech has the same kind of cracks so no problem. but after 4th one which was last Friday...i found some abnormal cracks. I actually can feel the crack with my nails.

this rotors are technically 4 months old with 4 track days...is this normal?


http://www.sokikuya.com/m3/rotors/IMG_0581.jpg

http://www.sokikuya.com/m3/rotors/IMG_0578.jpg

"Generally" you are ok unless the cracks go all the way to the outside of the rotor.

We've been fighting rotor cracking problems for a while. Eventually, we found we were over cooling the rotors...we've since removed the cooling ducts, gone to a rotor with additional vanes, and the rotors now run perfect temps and don't crack excessively.

Improper heat cycling of the brakes, and parking the car immediately after any session on track will have poor results to rotor wear and cracking. Also take the cool down lap serious, do a couple laps around the paddock if needed. You want a nice gradient of temp decrease after you pound the rotors for 30-60minutes. LOTS of heat is being generated and as Bryan mentioned if the cooling on track is not optimal (too much or too little) you can cause problems. Also depends on how the rotors were bedded in and what pads you are using.

I'm going with the new Performance Friction Direct Drive rotors for thier new design that will allow them to last longer and have better wear.

i am using PFC97.

i dont have cooling duct or anything. and i always try to lap around paddock...

Any chance you were at a track(s) that were particularly hard on brakes, such as Blackhawk Farms????

I know one of my local tracks (CMP) will put some serious heat into the brakes on just about any car. Those rotors look fairly normal for those driven hard on a short track/track that is hard on brakes in a 3300lb, 333hp car but they look like they have been exposed to some serious heat if that is after only 4 track days.

I can probably toast a set of brakes in one good weekend at CMP whereas they would probably last 4-5 weekends at Roebling or VIR.

lol right on, i was at blackhawk for 2 days. that was my third one. and then i just came back from autobahn countryclub south track.

are they still drivable (or trackable)? or do i need to replace them?

i am using PFC97.

i dont have cooling duct or anything. and i always try to lap around paddock...

Look into ducting. :D

the "expert" advice i have always heard is that if you can snag your fingernail on them, then they are too big and the rotor needs to be machined or replaced.

take that for what it's worth.