95_993

My front pads are worn and I plan to replace them tomorrow. The rotors are true and show little grooving. Do you always need to cut rotors when replacing pads? Curious.

johnsjmc

You don.t need to cut them if they are true. It may take a little longer to bed the pads because of the existing rotor finish,.Also there is a higher risk of squeal with new pads on used rotors

lexart

I had to replace mine at about 40K miles, they were pretty much worn. Have yours measured and see if you're within spec. The replacement rotors aren't too much from Suncoast, about $260 a set, as I recall . . .

95_993

I haven't mic'd 'em yet. But, they look surprisingly good. No cracking, no deep grooves and not a hint of vibration. I have typically always replaced rotors with pads on all my other cars (Audi, SAAB, etc). But, I have read of others swapping out pads in minutes and it occurred to me that maybe Porsche engineered a little more "meat" on the rotors and I might not need to change them with every pad change.

chaoscreature

You can always break the surface of the pad a little with some 120 grit sandpaper. This helps to knock the lip off the edge of the rotor and will help seat the pad as well. The best way to do this is with a disc sander, if you practice a little you can leave a really nice swirl pattern on the rotor. I used to work at a brake shop and this combined with properly lubricating almost always eliminated squeal (and yet my Porsche still squeaks)

lexart

Mine looked about the same at 40K miles, no cracking, no vibration, no deep groves. I tracked and auto-x the car some, with Pagid brake pads, so I measured the rotors, just in case. The minimum thickness is 30.0mm, and they measure 30.6mm new. Mine measured 30.2mm not quite gone yet but enough for me to 'splurge' for a new set. Got all new OEM bits with it as well, including the anti-squeal pucks. Put is all together, bedded the pads per instructions - squeal Now after 8K miles the squeal is still there . . . argh!

cgfen

at least consider cutting off the "lip" at the extreme outside diameter of the rotor, (if one exists).
Nothing wrong with taking a few .001s off the surface if you can find someone who will cut a drilled rotor.

Edward

No need to "turn" rotors at all, IMHO. If they are still in spec, shops do it primarily because of liability: they need to know the customer will roll out their driveway with brakes that are properly mated from the very first stop. We owners can use our head and "break in" the brakes over the next tankful, seating them as we drive, under normal conditions. While turning rotors does provide a perfect surface on which to bed fresh pads, they also remove rotor material, hastening your next rotor replacement. That's your trade off.

FWIW, many mechanics I've known or spoke to over many years admit to never turning them on their own cars, nor have I on any cars I've owned (or extended family maintained) for decades. The only important consideration is thickness. If you are not experiencing any problems with the brakes and this is just a standard pad replacement, then the rotors are true. Even the ridge is a non-issue since the pads you're putting in are the same dimensions as the one you're removing. So measuring thickness is all you really need to check for. Oh, and look at the holes and make sure that any cracks don't "reach" from hole to hole.

Edward

lexart

I just RTFM brake disk inspection section, so its fresh in my mind.

Factory recommends replacing rotors if the maximum crack length is 5mm, end to end or single crack from outer hole extends to the edge of brake disk . . .