irvineboy

Are you supposed to replace brake rotors everytime you replace brake pads? And brake sensor also?

Quadcammer

No to rotors. Sensors are a bit fragile so i would replace them

jtsmith18

Nothing wrong with replacing just pads but…How many miles on the rotors. How bad is the ridge on the outer edge? As a general rule you would want the rotors to last the life of the new pads. The brake sensors monitor pad thickness only. You don’t want to be driving later on with good pads but undersized rotors. If in doubt measure the thickness to be sure.

Pushinit

I agree with the other two answers but want to add that there is no absolute yes or no answer to this question. It all depends on the state of the rotors. You should ideally have old rotors turned while doing pads and if too much material is removed in the process due to warpage then they should be replaced. I have never replaced rotors at the first pad replacement, but I've known others who have needed to.

Inrev

Dealers will try to fleece you by selling you a new set of rotors. As a rule of thumb I change rotors every 2 pad changes. Still need to check wear though.

pinion

This is all probably obvious but… all of the above comments are for steel rotors… PCCBs are a bit different, they are not turned down nor are they measured for thickness and they won’t have the ridge from wear like traditional steel ones.

Schnave

Good article, with video, from PCA on inspecting the pads and rotors on a (last generation) Cayenne. The video (at the 1:05 mark) discusses whether to change rotors each time, or every other time you change pads on a Cayenne.
If you drive a Porsche, consider joining this great organization of fellow enthusiasts.

https://www.pca.org/news/you-dont-ha...-pca-tech-tips

chassis

I replace all of it pads, rotors, sensor. Standard brakes not carbon.

irvineboy

I couldn’t find where on the computer screen that shows estimated miles left on the brake pads. Does computer actually show how many miles left on front and rear pads?

fcpeuro doesn’t sell the rotors but has all the other parts. Does anyone have a good parts place that they get Porsche parts online?

KBell

Instructor. With a flash light, you look at your pads.
Get on hands and knees, and try to look thru the wheel at the thickness of the pads.
Also look behind wheel to look at inner pad.
Or just take tire off and look at the brake pads.
The computer does not show miles left on pads.
If physically not able to determine if pads are wore, then take Porsche to a independent shop.

Parts online.
Try Sunset Porsche, Beaverton Oregon.
Suncoast Porsche, Sarasota, Florida.

chassis

^this^ and I also use a plastic brake pad thickness measurement tool.

jtsmith18

Just to clarify, brake sensors don’t measure pad thickness but monitor and send a signal only when they are too thin. As previously mentioned, the only way to get a true thickness is to visually and or physically measure. Essentially the way pad sensors work is they are a wired electrical metal contact that is set in the pad that makes contact with the metal rotor at a predetermined pad thickness thus sending a signal and a light on the instrument cluster.

drcollie

Putting new pads on a worn rotor is not the right way to do it, its half-assed. There are grooves in the rotor from wear, that makes your new pads grip them unevenly. Only hack home mechanics do that and anyone that knows brakes will attest to that. At the very least, pull the rotors and take them to an Indy who has a brake lathe and have them turned so you have fresh, flat mating surface for the new pads. But now you have your vehicle up on jacks stands for a day or two until the shop gets to them, so that's not very convenient. I get new Rotors with each set of pads all around and do it right, then after the brake job is over, I will measure the old rotors and see if they have enough material on them to make it worthwhile to turn and save for the next brake job. Most the time, they do not. I don't ever let my pads get down to sensor contact, so I never replace those, just pull them off and put reuse them.

Never buy cheap rotors. I get OEM ones from ECS Tuning or Pelican Parts.

pbon

Another option is rotors from the company that makes them for the car — Porsche does not make the rotors. Sometimes you can find them. I just bought a set for my M5 for about $1000 versus $1500 for the BMW branded ones.

Put an outside micrometer on the rotor surface to measure thickness and compare to the minimum specified by Porsche, which may be stamped on the rotor circumference somewhere. Having them turned might get you through a new set of pads (probably just the shorter lived front pads). Depends in part on how you drive.

I am not sure about turning the surface conditioned rotors, but my 21 S does not have those.