There are a lot of misconceptions about slotted and crossdrilled rotors. I have read many of the posts in this forum and feel that I can add some helpful information. I have been in the performance brake and racing industry for a number of years and this is what I have learned from my own experience and the experience of others. Slotted rotors and crossdrilled rotors have absolutely nothing to do with keeping the brakes cooler than stock rotors. The main advantage to using slotted or crossdrilled rotors is that they will allow the brakes to operate properly at a much higher temperature than will stock rotors. When brake pads get hot,(even the newer friction formulations) the resins that bond the friction material together develop rise to the surface of the pad and develop a gas. This gas will actually float the pad away from the rotor. The same theory which makes engine bearings last so long, there is never any metal to metal contact because there is a very thin cushion of oil separating the two parts. Generally if the brakes get hot enough, they will lose their effectiveness and a spongy pedal will usually result. This spongy pedal is caused by one of two things; boiling brake fluid or the fact that you are trying to compress the gas that is floating the pad away from the rotor. What slotting and crossdrilling does is to allow a path for this gas to dissipate, while allowing the pad to maintain a good, solid, contact with the rotor, thus maintaning effective braking. Slotted rotors accomplish this much better in everything except all out race cars because they generally have a much longer life expectancy than crossdrilled rotors. Crossdrilled rotors usually crack because when cast iron parts are drilled, stress risers are developed which generally develop cracks after many consecutive heat cycles which can ultimatly lead to rotor failure. Additionaly, crossdrilling removes significantly more friction surface area from the rotor than slotting does, allowing a lower braking capability over stock or slotted rotors. The only real advantage to crossdrilled rotors is the reduction of unsprung weight that they offer, which makes for a considerable handling advantage in all out race cars. And the cracking isn't an issue, because very few heat cycles are seen before the rotor is replaced. Slotting does everything that crossdrilling does, with the exception of the weight reduction issue. The only difference is that they very seldom crack, they do not eat the pads as fast as crossdrilled rotors, and because they have more friction surface and mass than a comparable crossdrilled rotor, warping and temperature are greatly reduced. I hope this helps anybody who is interested...feel free to email me if any questions come up @
pmccle3928@aol.com 
