Rotor Question

My OEM brake pads are about shot at 20,000k, I'm going to replace the pads with Pagid Blues. In any event, the Porsche dealer says that it is necessary to always replace the rotors with each pad replacement. I've never done this on any other vehicles. Is this really necessary or is the dealer just trying to make a sale. My current rotors look like they are in good shape but I haven't been able to mic them. Thanks for any suggestions.

Some cars have very thick rotors. Some don't. They should be checked for thickness with a micrometer and also for runout. That requires a dial indicator. The standard rotor prices are generally inexpensive. If they pass the two tests above and aren't cracked, then they may be reused. IMO, however, I would change mine, as they do have some wear, and may were too thin before the next set of pads wear completely. Then there would be a safety problem.

I changed my pads at 26k miles, and had two years of road driving and many, many autocrosses, and probably 8-10 DE days on them. I didn't change the rotors because they weren't cracked and there was not even a noticeable lip on the very outside edge from wear. Check the thickness on them, but if there's no cracks between the cross-drilled holes, and there's not very much wear, then they probably don't need replacing. The Pagid blues will wear your rotors more than the OEM pads did, though. brad

there have been other threads on this. But my first blush is that the dealer is not very helpful to recommend rotor change without even doing a thickness measurement. PS.. what is the specification for minimum thickness for our rotors?? Back to personal experience. After running through a set of OEM pads after <8k miles and 2 DE's, my dealer recommended pad replacement, did a micrometer check of the rotor and saw no signicant wear. I've since reved up to Pagid Orange and added another DE. So, how soon will I need another set of rotors?? I'd like to measure them myself to make the decision... or at least "watch" the tech do the measurement, and then decide. Any other expieriences?? D

26K miles and no noticeable lip? Wow, I have easilly noticeable lip with 2K miles with Pagid Blues. Maybe I need to become less lazy, and throw stock pads for street use. Still searching for the lazy brake pad - good for street and track. I can live with the squeaking from Pagid Blues, but rotor wear seems greately accelerated.

Yup - One thing that seems to go unmentioned amongst the "I'm switching to racing pads" talk is that when you go to more aggressive pads, you're going to get more rotor wear... in some cases, depending on the pads, a lot more rotor wear... something to figure into the costs. I realize others have trashed the OEM pads for the track, but they seem to work just fine for me... but there must be something about my driving style that is easy on the brakes, since I'm an instructor, run in the advanced and instructor groups on the track (and keep up quite nicely with lots of other very fast cars and drivers) and yet I don't go through a set of OEM pads in 2 track days. YMMV. brad

I'm also curious to know this. I know it's stamped on the rotor, but short of taking the wheels off and looking at that, someone has to know.

I've got almost 20,000 miles on my car including hard track time with agressive pads and my rotors aren't shot yet, although they are cracking from the holes but no cracks as of yet between the holes, I don't really have much of a lip either. I'll keep running these until the cracks get closer together or I get a bigger lip on the rotor or they mic out of spec, but again, I've put my brakes through a lot of punishment and I'm not looking to replace rotors yet, hard to believe you'd have to with stock pads at just a few thousand miles more than me. As others said more agressive pads will wear your rotors faster so be prepared for that. Honestly I see no reason to run track pads on the street anyway, it isn't like you are going to get them heated up in daily driving to where the brakings distances will be any better...

20 million miles on a set of pads is truely amazing...

You're really not supposed to turn a set of cross drilled rotors. Idealy, you want to mate a new pad to a fresh rotor or a freshly turned rotor. That is why the dealer said to replace the rotors. Each pad wears a bit differently and creates a different wear pattern in the rotor. If you just swap pads, you won't have an ideal contact patch. That is why I've never understood (other than a cost savings) why people change pads in and out for track events. You should have a second set of rotors desiginated for the 2nd set of pads too.