Hey everybody, its been awhile now. In case if you guys have forgotten, I now drive a 1998 BMW z3.
I am thinking about purchasing rotors for my z3 because the ones with the 1.9L engine are not ventilated, they are solid. Same goes for the rears. In order to improve cooling, I was thinking about purchasing some cross drilled rotors to help transfer heat. However, I am worried that the contact area between the pad and rotor will diminish.
By what factor? I have no idea. That is my question, by what factor will my braking distance worsen due to the decrease in contact area between pad and rotor? That in and of itself is probably irrelevant. The braking distance is also determined by the coefficient of friction between the tire and the pavement. The larger the rotor diameter, the better the heat capacitance and thus better cooling is primarily. Secondarily, the further out from center of rotation the more effective the clamping force is. I am not looking to increase my rotor size however because of cost.
So....if I get drilled rotors, mind you they are solid discs, it will increase cooling but decrease the structural integrity. But what about slotted rotors? Because they are channeled, there is more surface area, however, the increase in surface area is not acting as a fin (for heat dissipation). I suppose the last question is, should I say to hell with aftermarket rotors and just live with solid, non-ventilated, rotors?
Is there a difference in braking performance about how the drills or rotors are pointing backwards or forwards? Intuitively, it shouldn't matter.
Thanks guys. I'm currently a student majoring in mechanical engineering. Im already leaning toward drilled rotors (though they are more prone to cracking). Slotted rotors will help with pad cleaning and bite but I'm almost positive it will not help with cooling despite the increase in surface area exposed to the environment. I'm asking for experience.