Rick Kim

Porsche does not have drilled rotors. the holes are cast into the rotor from the begining (nt)

silvertip

cross drilled rotors, unless they are cast in like porsche or (maybe other mfgs?) tend to crack at the outer edges of the holes. Even the cast ones do that but not as soon, but it does let some of the hot gas's from the brake pads escape. Gas slots do the same but does not have to worry about cracking holes and the rotors will last longer. So either is good for its intended purpose of eliminating hydroplaning via pad gas against rotor under hard/track use. Bottom line on cross drilled is they are lighter for unsprung weight, but longivity (sp) not their long suit. Gas slots do the same, but obviously weigh more. But both will also help in the rain since it will wipe water as well as gas - instant grip! Which would I personly choose are gas slots. I have been using them for years and they are great with no problems at all. Not as pretty as cross drilled though. Although as a final note, some brake pad mfg's do not recommend either since their pads may require all the rotor surface that they can get. About 4 to 6 years ago "performance friction brake pads" did not need either because they left a coating on the rotors which caused instant grab which was good, but I didn't like them that much because they coated your rotor with their brake material and was hard to blanchard grind off if you were trying to get rid of a slight warp after a hard track day. As a final note, you might want to try frozen rotors at "frozenrotors.com" I think that is their site. They tend to not warp as easy as non treated rotors. Whew! hope this helps alittle.

Boss Hogg

correct on this matter. Racing cars, of course, do not use cross drilled brakes.

Geza

that excess material at the outer edge of the rotor (caused by the pads wearing the rotor) is preventing him from removing the caliper. Wedging something between the pad and rotor will force the caliper piston in, thus generating more play at the caliper/pad/rotor interface; with enough play, the caliper/pad will clear the excess material. It then can be removed easily.

I don't think your memory is bad; it's just that your most recent experience has been with the brand new rotors (which didn't have the excess material on them) from your S4, correct? :^)

OTOH, Maybe I misinterpreted his question.

Are you doing the Summit Point QCUSA event this year?

Geza
99.5 Avant 2.8qMS
97 Boxster

Warren Wang

Yeah, I'll be at Summit a few times this year. Probably like 6 track days up there, 2 of them being for the QCUSA event.

I'm also gonna head to VIR near the VA/NC border for 2 days, and Mid-Ohio for 2-3 days. Plus auto-x's when I can stuff them in there.

Re: the calipers. If you've loosened the caliper on the A4, I think you can just push/pull against the caliper and it'll retract the pad, rather than wedging something and scoring the rotor/pad. Hope this makes sense.

Warren