This is the reason you need to look at your rotors every time your Corvette comes off the track. The small cracks really aren't an issue, but once the cracks reach the edge of the rotor, you need to change them out. Based on what I'm noticing with C5 and C6 Corvettes, you really need to carry extra brake rotors with you if you run track events. Danny feels the best brake rotors are the stock GM rotors. In fact, a lot of the aftermarket rotors are simply GM rotors with slots milled into them. Or, with holes drilled into them for the street car crowd.