mudman2

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Cayenne Nick

I was just at the dealer Tuesday for my spring oil change/check up. I was informed that my front pads are down to 4mm and the warning light will come on at about 3.75mm. As well, I was informed that you must change the rotors when you change the pads. I have had a lot of other vehicles over the years that I have changed the pads but not the rotors unless they were pulsating etc. Is it a must that the rotors be changed when I change the pads? Thanks in advance and thanks for th DIY.

Andy E.

Michael, where did you source these from? Is there a big enough difference in longevity between the stainless and the cast rotors to justify the hike in price?

Slow Guy

I haven't had the pleasure of changing them on the Pepper yet (they were just replaced when I bought it CPO) but I suspect the rotors don't wear out completely in 1 set of pads it's just they don't have enough life (thickness) to last through a second set of pads.

As I understand it you can expect to change the front rotors every time and the rears every other time. Now if you want to push your luck (or just change the pads a little early) replace the front rotor every other time too. However, I wouldn't recommend that unless you are able to monitor the rotor thickness between pad changes.

Andy E.

Porsche and Mercedes-Benz dealers have adopted a new habit when it comes to brake jobs. My S.A. advised me that it no longer pays them to remove the rotors and re-face them at their high-labor rates as there is usually no guarantee that there won't be a brake squeal or pulsating pedal afterwards. Provided that the rotor thickness is well within the norm, replacing rotors avoids the dreaded potential brake squeal when re-using machined discs.

Even if the used rotor surface is fairly smooth and non-grooved, there is always the raised inner raceway and raised outer rim of the rotor that remains. If the rotor is not replaced or machined, the new pads may rub on these raised surfaces which will surely create a squealing sound.

medtech

Nick,

I bought the CS w/ 35k on the clock and I'm not sure what was done to it by the prior owner (other than routine oil changes, etc).

At 62k sensors went off and I changed the front pads w/ Hawk Dustless. At that time I chose to leave the rotors alone. They had a lip on them, but otherwise seemed fine.

By 70k I felt that the front rotors had too much lip on them and the pedal travel had increased considerably. The pads were still fine. (unfortunately I didn't have a rotor caliper to measure them). When I took them off they were worn, but no real warping or uneven surface wear (and I had no issues w/ pulling to one side or vibrations during braking).

At that time the rear pads were low, but the sensors had not yet gone off.

The car functioned and braked just fine.

I changed the pads and rotors all the way round at 70k, using Hawk Dustless pads and zimmerman rotors (FYI NO brake squeal at all since going with the Hawks).

IMO the rotors will last you about 1.5-2.5 pads, if you push it. But that means you will have to service the car an extra time, and the pads/rotors will never be on the same schedule. The rotors themselves are relatively cheap (if you DIY) so it really doesn't justify your time/money not to change them at the same time.

(Disclaimer: Once again I don't know what the previous owner did. They may have changed the front pads before I got the car, I doubt they changed the front rotors and I highly doubt they changed the rear rotors. So that means I likely got about 60-70k worth of hard city driving out of all 4 rotors, not bad IMHO)

juejaimon

I see many diys for the front rotor replacement... has anyone seen any for the rears?

TIA

medtech

The rears are essentially the same as the fronts with a few additional tools needed. If you read thru this entire thread, I think we have addressed the rears (verbally, but no pics).

The main issue with the rears is that the bolts holding the calipers and rotors are often "frozen" in place. It is a cramped working space, and you obviously don't have the luxury of turning the wheels in order to get better access. Therefore you may need to work out some type of breaker bar solution on a swivel or angle. I would also suggest hitting the bolts with WD-40 and letting it sit for about 30 min to loosen them up a bit.

The other issue is that you will need a special set of XZN sockets. (Why they use a different bolt on the rears is beyond me.) These are essentially a 12 star torx bit. They are only used on german cars and you will not be able to find them at sears or the local auto parts store. They have to be ordered. I ordered a set of "VMF XZN100 4m thru 16m" off amazon.

Hope that answers your Q.

If you run into any problems, PM me.

juejaimon

Thanks medtech. I have a set of XZN ordered that has the 16 Mil within. If I recall, the rear brakes are a disc and hub combo. I attempted to change it last year but didn't have the XZN bit. After seeing the combo status, I felt unsure of myself to do the job.

medtech

I think the "hub" you are referring to is the parking brake. Although it looks like one big unit, it's not. The rotor goes on like normal and just sits on top of the parking brake assembly. The extra screw in the rotor is just to cover the parking brake adjustment screw.

cordsig79

Craigslist trolling pays off again. Found set of 2 Zimmerman rear rotors for 125 for the pair.

I am assuming all rears are 330 and since mine is the BASE, it should definitely have 330mm correct

seankrider

Didn't see a lot of info on changing the front rotors, so thought I would include some pics and a few tips:

(1) Trick on the rotors is removing them without taking off the hard brake line (coming out of the center of the red calipers, with the nut):

seankrider

(2) Brake line is attached to the vertical pivot bearing in two places; this is the upper bracket and bolt (looking out the wheel well from center of vehicle):

seankrider

(3) The bottom bolt, further down the pivot bearing (slightly out of focus, behind the c-clip; again, looking out wheel well):

seankrider

(4) Unbolting the lower connection - could not reach with any socket setup, so used a hex-key set (soft-line pulled out of c-clip to better reach this one):