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YOUR RESEARCHCan I turn my rotors?
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Replace em yet haha
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Suggestion
Measure the thinnest part of the rotor and make that that's more than the min spec stamped on the rotor or in the repair book.
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Suggestion
They weren't really worn(well within spec.) but there was wavyness that you could feel when running your finger down the rotor.
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Suggestion
Some shops use a grinder to grind the rotor surfaces and a grinding wheel less afffected by any casting scale in holes.
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I just did my 60k service and this weekend or next I will do my brakes, flush the fluid, etc.
AFAIK these are the original rotors and they have a slight lip on the inside and outside of each rotor. More on the front than the rear but all 4 rotors do have a slight lip. I think they are still in good enough condition to simply put a new set of pads on and not worry about them until the next time my pads need replacing.
So can I have these rotors turned? If not, how much are new ones?
Cross drilled rotors are harder to turn and in doing so often results in some issue in consistency of thickness. The cutting bit can be miss guided when hitting the holes. It's possible but not as easy. If you do decide to try, have someone who's done drilled rotors before. Often, it's simply not worth the effort.
Not sure what you mean by a "lip" in your rotor. If you have varying thickness that requires turning, you should probly just replace it. Measure the thinnest part of the rotor and make that that's more than the min spec stamped on the rotor or in the repair book.
I had cross drilled rotors on my 280ZX Turbo and Nissan's Competition Dept. said they couldn't be turned. My dealer says the same for the 996.
Brakes have always been a Porsche strength and I'd be leery of deviating from the company line.....
When I brought my 2001 in for a routine service with 15,000 miles on it they called me and said I needed new rotors. I went down to the dealership and the lip on the rotor was barely enough to catch your fingernail.
The service manager told me it's Porsche policy to replace the rotors if there is an edge, I told him fine, then you pay for them. I made such a big deal about that they in fact did pay for the rotors.
No way a care with 15K that's never been tracked would need new rotors!
If you turn CD rotors they don't dissipate heat nearly as well, and in turn, the structural integrity of the discs are compromised.
It's a couple hundred bucks for new rotors. Small price to pay for safety (though I do understand the argument about not replacing anything unless absolutely needed).
I just had the Porsche Dealer turn my cross drilled rotors. They said usually, there is not enough thickness to turn them, but after measuring the rotors, the Dealer turned them.
general rule is if the "lip" is more that one millimeter then its time to get new rotors. The independent shop i use to work at turned rotors all the time but i refused to do it. Not good to go under min spec and its a Porsche not a Kia...we use the brakes a lot harder than most cars and why would you want to take material off the rotor. My .02 cents...
I had some old AP Racing CD rotors turned, also, and never heard that CD rotors would not be turned before this day; even if the explanation above could make sense...
As long as rotor thickness not at minimum CD rotors dissipate heat just fine. What's the difference between a rotor reaching a thickness -- still not yet at minimum -- by wear?
One problem is if CD rotors do not have drilled holes but cast then as rotor is turned cutting tool encounters cast scale which is hard and cutting tool can deflect a bit and each hole will have a tiny series dips after it.
Some shops use a grinder to grind the rotor surfaces and a grinding wheel less afffected by any casting scale in holes. IIRC some company makes a rotor grinder than mounts on car and can refinish rotor surfaces on car. I would hope the grinder has a superb vacuum system though to keep any grinding dust from getting on any suspension component or on car's glass or painted surfaces.
After refinishing rotors all holes should have enough chamfer so even if rotor wears down to its mininum thickness any casting scale can not come on contact with the pads.
If the pads encounter casting scale pad life will be short.
I'm pretty sure genuine Porsche CD rotors have holes cast in but are then drilled to remove scale or probably have enough hole chamfer to keep any casting scale in hole coming in contact with pads.
Sincerely,
Macster.
I don't understand why people turn rotors in the first place... They're either close to the min thickness and deserve to be replaced, or they don't really need to be turned - it's just a way for a shop to charge you a little extra. (And, usually, since fixturing the rotors onto a lathe is a secondary operation (secondary to both the original machining process and to your "on-car lathe" - as Marlon points out) there will be an inherent alignment problem that will cause the "turned" rotor to be non-concentric and have more run-out than before.
Way back in the day, when rotors were quite narrow (and usually solid) they could warp - so turning them was useful in reducing that warp. But, in today's modern rotors (and especially well-designed high-performance ones), I feel it's a waste of good time and good money.
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Resurfaced mine at 40k. Vehicle now has 55k. Car initially had a really bad pulsation coming from the rear(verified by pulling up on the e-brake). Removed rotors and sent to a machine shop to resurface. Pulsation gone. They weren't really worn(well within spec.) but there was wavyness that you could feel when running your finger down the rotor. Cost $60 as compared to a couple of hundred. Spent the extra money on a new set of floor mats.
