gtp420 said:
It kinda depends.I think all you need is slotted. If its a good drilled rotor then the hole should be cast in to the rotor , the cheaper ones are drilled out. The problem with cross drilled rotors is that they crack.
Uh, wrong. The only rotors that have holes casted into them are the (this is where I can't rember) I believe it was the ceramic rotors for porsches. Normal rotors are drilled.
Again if it's done correctly cross drilled rotors function just fine, but are known to crack. However, with newer pads slotting and cross drilling isn't even necessary. So, both are more for looks than anything else.
I have slotted and cross drilled on all four corners simply because of cost. I did a 5 lug swap along with 26mm 300zx brakes in the front. Finding oem blanks in that sized turned out to be slightly difficult. Brembo only made the 30mm rotor (and when i found the rotor I needed it was expensive). So ebay sold me front Z rotors for cheap and the rear rotors i got that were slotted and cross drilled (again, I just did a 5 lug conversion in the back, no z brakes) were just cheaper than getting blanks. I figure that if/when i start to see cracks in my rotors I'll just spend the money and make sure I get some zinc coated ones that won't rust nearly as much and at most I'll just get slotted ones.