ORIGINAL: Jbauer

I know how this sounds..i really do- but my uncle is one of the engineers at Brembo. I asked him this same question- and i got more than i bargained for with a 1 hour conversation on brake rotors and pads...i'll tell you the rundown.

When you cross drill rotors- each hole is one less area the brake pad has to bite on- in short cross drilled rotors suck,will increase your stopping distance, and are useless because brakestoday don't even need the use ofdrilledrotors tovent. He told mefor serious braking, and best pedal feel stayaway from drilled. he also told medrilled rotors WILL crack in a severe raceenviroment and that with thedrilled rotors they sell- they warnon their site not to use it in a race application (maybe someone can also check this on their site)and he told me that even porsche admits- they do it only for looks.

Then on to drilled slotted. he said only a moron would run these..not only are you drilled losing braking surface, your slotted between the drills, and that there just as bad if not worse than drilled rotors.

He informed with any of the two above- he is absolutley certain no one feels a diffrence with drilled, and especially drilled/slotted unless there original rotors were worn- and that ppl with drilled rotors are suffering a LOSS not a gain and would recieve better performance from O.E than drilled.

For best braking, and a diffrence your most likely to feel- get slotted rotors. He told me he believed every car should come with slotted. The slots bite into the pad, causing friction, and the slots themselves also help remove any heat. he told me slotted rotors are the ONLY choice in rotors
and i believe him because he was important enough to be taken to Germany to work with other engineers. won't see me in any more drilled and especiallly not drilled slotted..thats that much less surface area to brake on.

ORIGINAL: tbirdscwd

I was always told the main reason for slotted rotor is to vent the hot gas that is procuced by the friction between the pad and the rotor. If there isn't some sort of slot or avenue for the hot gases to escape, under really hard braking conditions your brake can produce enough gas and retain enough heat to reduce the friction capability of the pad. Also refered to a "Brake Fade."

Of course there is another form of brake fade being the boiling of the brake fluid, but thats a whole other story.

edit: sp