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Originally Posted by Chase300
You'll never have problems on a street car with properly made cross-drilled rotors.
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Never say never.
The issue is heat cycling. If you repeatedly force your rotors above and below a critical temperature threshold enough times, they will begin to develop tiny surface cracks, which will eventually grow enough to require rotor replacement. Drilled rotors will do this significantly faster than plain or slotted rotors.
Normally this does not happen on the street. However, I have a few customers in southern Florida who drive 140mph on Alligator Alley late at night and conduct repeated high speed braking exercises. This is what I would consider full race conditions and the ideal conditions for destroying drilled rotors.
On the other hand, it is possible to take drilled rotors to a race track and not have them crack. If the track has repeated braking zones, with no long straights so that the rotors get glowing hot but never have a chance to drop below a critical temperature, then heat cycling does not occur and you can run them all day long. Again, it's all about repeatedly driving them above and below a critical temperature range that causes them to self destruct. A track with heavy braking zones, followed by long straights where the brakes can cool off is a brake killer.
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If Cross-Drilled is so bad and crack, why does the Corvette C-6, even the Z06 version, Porsche and even Ferrari equipped their cars with cross-drilled rotors? Only car I've seen with slotted is the SRT LX...and its probably because of cost. Not saying they are worse than cross-drilled, but I've been very satisifed with the performance gain I've received from cross-drilled rotors.
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In a word, marketing. The perception among the general public is that race cars use drilled rotors, even though these have fallen from favor in racing many many years ago.
You give General Motors too much credit for brake engineering (or deployment) when you hold them out as an example. In the case of the Corvette C6 and C6 Z06, the rotors are directional, but they didn't bother to make a right side part. In other words, the driver's side rotors are correct, but the passenger side rotors are backwards! The engineers designed the proper curved vanes inside the rotors for cooling, but the beancounters decided to save money by only producing left side rotors. See:
How to properly install plain, slotted, or drilled brake rotors for a bit more clarity on this topic.
As for Porsche and Ferrari, they may have a better idea about what they are doing than GM. Even with such exotic cars, the vast majority of them never see any track time. Since drilled rotors save an additional quarter pound or so over slotted rotors, there's a slight weight (and thus performance) gain to be had from using them. Furthermore, drilled rotors produce slightly better bite than slotted rotors. So if a car was NEVER to be taken to the track (or abused on Alligator Alley), then from an engineering perspective, drilled rotors are the better solution. That's why, for example, I put
drilled StopTech big brakes on my BMW 540i 6-Speed. I'm never taking that thing to the track. Not that it wouldn't be fun. But the Corvette would be far more fun.
So that's where it comes down to a personal preference thing. I look at my upgraded BMW brakes and am somewhat conflicted by my decision. I know drilled rotors made sense from an engineering perspective, since the BMW is never tracked. But many years at the track, seeing almost nothing but slotted rotors in the pits, has changed my sense of aesthetic regarding brake rotors. To me, slotted rotors look more serious than drilled rotors. That's one reason my SRT8 got
slotted StopTech big brakes.
Don't even get me started on slotted AND drilled rotors!
