Bill Wagner

I took my car to a local p-car shop today, primarilly to get new tires put on. This shop does not have a good reputation, but I figured they could handle some simple tasks (tires, balancing, and checking out the squeal from my brakes).

As far as the squeal from my brakes went, I took in a TSB about it and brake dampers. I was assuming the work would include new dampers, and maybe turning the rotor and putting on new pads. Like I said, this place does NOT have a good reputation. In any case, I got a call from the tech and he's claiming my brake pads have dried out and glazed the rotors. I told OK, then turn the rotors. His response was he couldn't turn the rotors because Porsche doesn't recommend it. He's also (surprise, surprise) recommending what amounts to a complete overhaul of the rear brakes...new rotors, new pads, new dampers, etc. etc.

My question for the day: Is turning rotors not recommended. If not, then why does my 964 spec book provide information about the limits of turning the rotors? (I suspect I know the answer to this question, I just want verification).

Thanks in Advance,

Bill Wagner

Randall G.

Hi Bill,

I don't have my receipts in front of me, but I'm 90% certain that I've had my 964's rotors turned before--by a very reputable shop.

That said, I have replaced all my rotors at least once, and might have replaced the fronts twice (again, I'll check my receipts tonight). The 964 rotors seem to be pretty soft (price we pay for that wonderful braking power), and apparently you just can't get that many miles out of them.

Tom Sharpes

Both the front and rears on my car have been surfaced. I think he is trying to take you for ride.

Randall G.

Hi Bill,

The history of my car's brakes:

(R) 28k miles = Replaced rear pads
(F) 34.4k miles = Replaced front pads
(R) 50k miles = Replaced rear pads, machined rotors.
(F) 63k miles = Replaced front & rear pads and front rotors.
(R) 86.7k miles = Replaced rear pads and rotors.
(F) 90k miles = Replaced front pads and machined rotors.
(R) 104k miles = Replaced rear pads.

Summary =
Replaced rear pads x4
Replaced rear rotors x1
Replaced fronts pads x3
Replaced front rotors x1

Incidentally, I have never seen the brake wear indicator light in my car--ever. I get the impression it's worthless.

Steve Nugent

Had a major brake squeal problem when I got my '91 C2 in January - sounded like a trash truck if I just touched the brakes. Took it to Jose at Autobahn in Fairfax, who did two things - turned the rotors and installed Metalmaster pads front and back (no problem on the front four piston calipers, but its apparently a little tricky to put these on the two piston calipers in the rear - Jose needed to modify them a bit). Result - driven about 5,000 miles so far without even the slightest hint of a squeal.

J richard

On older cars Porsche did not recommend refacing the disks unless absolutely necessary due the reduction in the thickness of the wearing surface which can lead to cracking and the additional mass which helps dissapate heat. The only time it was nescesary to reface the disks is if there has been metal to metal contact, the disk is cupped too severly or it has excessive runnout/warpage. I don't know if they have changed their thinking on this but it always made sense to me. Unless a disk showed grooving or chatter marks, I brightened them up with sandpaper or a 3M pad, slapped in new pads and they always worked fine. Like all new brake jobs you must wear the pads into the disk, this happens slower than a resurfaced disk, oft times a regrind is so coarse you loose considerable pad during the process. On cars with the wear sensors (basically a wire that is cut by the corner of the disk when the pad is worn) if the disk is cupped and sharp at the edge it can prematurely cut the sensor wire before it is really time to replace the pads, those should be resurfaced as a matter of course.
The questionable recommendation you got could have been a misinterpretation of old porsche guidelines.

Berkley

According to the service records on my 1991 C2, the previous owner had the rotors removed and machined by an authorized dealer at 23,000 miles ( in 1997 ). The car now has 29,000 miles and I had the rotors, pads and sensors replaced two weeks ago at a cost of roughly $1,000. Fortunately, I had a " sort out " arrangement with the prior owner as a part of the purchase agreement and this work was for his account. Any further work on the old rotors would have taken them under the minimum specifications set by Porsche ( per the dealer I am using now ).

Interestingly, the warped rotors were not noted in the PPI, but my first higher speed drive after buying the car revealed that the rotors were history. With a low mile porsche that had very limited use in four years, I expected some surprises .... but the price of admission can get heavy quickly. I was lucky this time.

Bill Wagner

Thanks for the responses everyone.

This particular shop has earned something of a reputation for "throwing parts" at a job. All their mechanics are commissioned, meaning they get a "cut" of all the parts they sell. I think the work to finally resolve the problem will be done elsewhere...maybe by me if I have the time.

Thanks,

Bill Wagner

Adrian

Dear Bill,
I have checked the manual. You can resurface the rotors as long as you stay within the prescribed tolerances,
Ciao,
Adrian
911C4