Quote:
Originally Posted by LiM3y
I am surprised there are not more posts about warped rotors at the track based on the discussion here. I am also surprised that the rear rotors needed replacing at the same time as the fronts with the M3's brake balance.
Since switching to race pads, and going through a set of Hawk DTC-70's in five track days, I haven't had any of the symptoms of shudder under braking associated with either pad deposit with OEM pads or warped rotors. However I did have front rotors replaced due to small cracks forming at the venting holes. Using race pads, the kinetic energy dispersion and temperatures are the same (kinetic energy is higher by v^2) as using OEM. If the rotors were warping under these conditions, wouldn't the problem get worse with better pads?
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Agree on your warping point
. Using a more track oriented pad will definitely reduce, if not eliminate bad pad transfer.
Question though, how bad were the cracks in your discs?
Cracks appearing on cross drilled rotors is fairly normal when used at the track. As long as the cracks don't stretch from one hole to another, or worse from a hole to the outside edge of the disc, the discs should be perfectly safe to use.
I had cracks appear right after the first couple of track days with the car. Kept the discs for three and half seasons (at 12-15 track days per season). I eventually had to replace them because I had worn down the thickness of the discs. No warping or cracks connecting the holes. Stock discs are pretty sturdy. I use crappy Hawk HP+ pads, cheap and better than stock but definitely not the best out there.
Same experience with my E46 BTW (I was running EU spec cross drilled discs).