Post by
C-Kwik »
https://forums.nicoclub.com/c-kwik-u426.html
Tue Aug 29, 2006 9:40 pm
Cross-drilling and slotting were designed with a purpose. Slotting helps wipe the brake pad surface exposing fresh pad material. Wears a bit faster but increases the original bite. Cross drilling also can help wipe the surface but also allows outgassing should you be running on the hot end of a brake pad's temperature threshold. Brake pads vaporize beyond a certain temperature and when this happens, it traps a layer of gas between the pad and the rotor. It makes it difficult to stop when this happens and when it's bad, the pedal will still be quite firm, but the brakes end up quite useless until they cool down some. With the venting, it has some cooling properties as well. But with both, you have to be careful. Slots should not be very deep. They can easily become a point at which cracking can occur if some company decides they can machine too deep without some level of thought put into this. I'd speculate it would probably be safe as long as the deepest points don't breach the minimum thickness levels.
For cross-drilling, You'll want to look for rotors that have the cross-drilling cast into it rather than drilled. These tend to be pricey, so don't expect to find any. The next best thing would be to look for holes that are radiused(rounded edges). Drilling the rotor can leave sharp corners that are a possible stress point when subject to a lot of heat. Radiusing helps to eliminate this issue, but I'd still be careful if it's drilled. Perhaps if you go with a bigger than OEM braking system, the drilling will be less of an issue as temperatures should be lower. As an example, the popular Z32 upgrade on a S13/S14. I used Stillen cross drilled rotors at track events and never had a problem. Their cross-drilling does have radiused edges.
Stick with quality brands. There are differences in the metal content between premium rotors and your bottom of the basement cheap rotors. This can affect everything from wear, to heat management, corrosion, noise, and and warping.