Stinkfoot

Hello All,

I'm new to the forum having just bought my first AMG, a 2008 C63. It's without question the most fun car I have owned. I appreciate the value of a good forum and I'm happy to find so many involved and knowledgeable owners here.

Yesterday, on the way to the dealer to have a warranty issue repaired, the check brake pad light came on so of course they pushed me for a brake job. The service writer explained that the front rotors are just at minimums and can't be reused. I have not measured them myself yet, but I'll assume they are at least close.

So here is my question: The "minimum" (the value stamped on the circumference of the rotor) appears to be the minimum thickness to which a new set of pads can be installed. That would be different in my mind from the minimum value that is functionally acceptable, given that the next set of pads will further wear the rotor well below the "minimum". The parts guy told me that most folks get two pad sets per rotor. It would seem to me that the minimum is then 50% of that "functionally acceptable" number. So my point would be that, give or take a thousandth or two, there ought to be some flex in that spec. for an involved owner.

I get that brakes are important, but I'm loath to toss a good set of rotors. My years on this Earth have taught me to approach dealerships with grains of salt. I'd appreciate the opinions of others on this matter.

Thanks

SF

olszowa12

I'm not sure if that's what you're asking but I always drive 500-1000km after the "change brake pads" light comes up.

mzcloud

I am in the manufacturing/distribution brake business. The MIN Thickness stamped on the rotor is the minimum thickness the brake rotor can function. If it not safe to use the rotor if it falls below minimum thickness. In other words, if you put new pads on the rotor and the rotor is 1 or 2 mm higher than the minimum thickness, I suggest get new rotors because within 10,000 KMs, it will be at the border line. But usually one rotor can last 2-3 pads.

mzcloud

The change brake light is an indicator for the brake pad only, when the light is on, there is still approx 25% pad life remaining. So driving 1000km is definitely fine, unless you are doing extreme braking, can probably drive few thousand kms.

Merc63

Does the car have performance package? Two piece front rotors?

It will have the min thickness stamped on them. Measure with a caliper to see how close you are. Mine (2pc) were down 1mm after 45K Km. I put new pads on all 4 corners and all was good. From the measurements I took, there is 3mm of wear from new to the limit. You should be able to get around 80K-100K Km from the front rotors.

If you don't have the 2pc rotors.. News ones are only 200 bucks... The 2ps are like 1300 each.

DuaneC63

I've never been able to just pop a new set of pads on any AMG I've owned. The rotors were always too worn and had to be replaced and this was at an indy they showed me both the allowable spec and the actual measurement of the rotor thickness. Personally the brakes are too important to skimp on. I usually have everything replaced.

DuaneC63

And if you have ceramic rotors they are about $4K each. Your basic $20K brake job with new pads and labor (its called the Porsche experience).

olszowa12

Stinkfoot

Thanks for the comments guys. I do have the one piece rotors, BTW. I might have given the impression that I'd be likely to skimp on brake maintenance. I will not. I just want to understand the situation before I order parts.

I had a look this morning and came away no wiser for the effort. It is unclear to me whether the rotors are measured individually or as a pair. I looked at the edge of the rotors for a stamped marking and found none. I did find a "14" stamped on the inside of the inboard rotor. 14mm is greater that the lip.

I measured them as a pair and got 35.25 mm then measured the lip and got 36.1 mm. Wear appears to be less than 1mm between the two if one assumes the lip is unworn. On the other hand, if the 14mm is the spec for each rotor, then I'm significantly under.

Mort

from james @ ACGSD

Front rotors 36mm; service limit 34mm; wear limit 33.4mm

You measure the total width of the rotor friction surfaces.

The spec is stamped on the outer lip/edge of the rotor.

Your rotors sound like they are fine for reuse.

Stinkfoot

Thanks Mort. I do appreciate your help.

The service limit and wear limits are what I was alluding to in my first post.

I looked carefully around the lip/edge/ circumference of the rotor and saw nothing. Oh well.

Dave

Jon2007E63P30

For a 36.1mm initial thickness, I have seen 33mm as minimum (1.4inch, 1.3minimum)