KevinC - SJ,CA

I did replace those rotors shortly after that picture was taken. Even the deepest valleys didn't go beyond the 2mm wear limit, but the cracks were bothering me and it was a convenient time to replace them. I have since replaced another set of rotors. Again, they had a substantial amount of wear remaining, but the cracks radiating from the holes were worse than those shown here, and were starting to get very close to the outer edge of the rotor. I would have gotten significantly more service from the rotors if not for the holes.

I tracked a '98 Boxster for quite some time with the vented, but non-perforated rotors (I wouldn't call them "solid"). I was very happy with the performance of those brakes. I guess I am just not sold on the arguments about the benefits of perforated rotors regarding cooling and out-gassing.

I could make an argument that the cooling of the hardest working outer portion of the rotor suffers because the holes allow some of the cooling air to escape from the internal vanes before it reaches the outer edge of the rotor. (Notice how the inner portion of my rotor is in much better shape then the outer portion.) The holes also slightly reduce the mass of the rotor, reducing its ability to absorb heat, producing slightly higher rotor temperatures.

As for the benefits of the perforations in dealing with out-gassing from the pads - I don't believe this is a significant problem with modern pads which have been properly bedded-in. I certainly never experienced pad fade with the unperforated rotors of the '98 Boxster, and I don't hear this complaint from my track buddies who continue to work those brakes very hard.

NetManiac

I would think the slotted rotors would be the best of both worlds. You get the venting and cooling without having to worry so much about cracks.

I also worry about the cracks in my rotors, but keep being ressured that until they actually connect there is nothing to worry about. I have a complete spare set I take with me to every track event though.

Alan Herod

Kevin, I agree with your position concerning drilled rotors, but have no quantitative data to back it up. I have had great success with slotted rotors on the SC - they did begin to crack, similar to the cracks in the drilled rotors shown, after they were probably below the wear limits. The SC's rotors are 'thinner' to start with. I have heard that some have had difficulty finding non-drilled rotors (as in don't exist) for the Boxster S and the 996. I can not verify the veracity of that statement.

I purchase my rotors from Paul Weston.

JeffES

As to outgassing as an issue, do a bit o' Googling (is that a verb??). It's a very serious issue, especially as braking loads increase. Several automakers have had serious issues - the most notable being GM's light duty trucks w/vented rotors - the pads would accumulate so much debris & gasses that the pads would be forced back off of the rotors. Their first solution was to "slot" the rotors, a better solution than perforated, BTW, but the $$$ were prohibitive. I agree w/ "net" and Alan (above) that slotted rotors, while a bit $$$, seem to be the best of both worlds.

J
PS - of course, you're correct - where I said "solid" rotors, I should have said "vented".
PSS- I know it's been debated ad nauseum, but I've never found solid data on slotted vs perforated. Anyone??? I'd tend to vote slotted, but if there's evidence.....