dreilly36

I have a p31 with 78000 miles. Pretty sure on original rotors. The back pads are getting low and are pretty noisy. I want to replace them soon but the rotors need to be turned.

Is that ok? At what point can they not be?

Eric ATP

The rotors are cross drilled and you do not want to "turn them". If they are not out of spec on thickness or runout just install the new pads.

Eric ATP

Also if you don't care about the weight difference you can just install one piece rotors. They go for about $140 factory mb if you order online. Direct swap as they are the same... Just not 2 piece.

tpliquid

whats thickness measurement

Eric ATP

Should be stamped on the outer edge of the rotor. But I believe they are.
Fronts the rotors new are 36mm, wear limit for service is 33.5mm, Wear limit is 33mm

You need to check the runout also unless you want to be buying new calipers. If they wobble your going to destroy the Pistons and calipers.

I doubt highly with that mileage your rotors are in spec at that mileage of they where original.

AA717driver

78k mi. on an original set of rotors? Admirable restraint...

TC

Phil Chow

78K Miles...man, get some new rotors.

Merc63

I got 93000km on my original rotors, they are still doing great. Measure them. Is there any pulsation in the brake? If not, throw new pads on and watch the thickness. There is wear indicators drilled slightly into the rotor face as well.

zcct04

DReilly36 - Just to clarify - is there a reason that you think the rotors need to be turned?

ENVē

Where? And what do they look like?


I have 26k miles on my rotors and I want to swap pads because they are squealing a lot and possible loose in the caliper at times of speed. How do I know if I need to replace rotor?

Eric ATP

Guys get a basic micrometer at the very least to measure your rotor. In reality you should also check it with a dial indicator to check runout.

At 26k I highly doubt they are worn out from normal driving. If you have tracked the car or drive it hard a lot then maybe. The only way too really tell is measure and check the specs. The dealer should do that and any decent Indy should as well. Very easy to do yourself also. Bembo brakes are very easy to work on.

I am also assuming everyone is flushing their brake fluid every 2 years. 4 max.... Also simple.