Does one need to remove grey coating from surface of new E500 brake rotor

Hi,
Installing new brake rotors on E500. Notice that they are coated in dull grey finish, that is no metal is exposed.
I tried to rub it off using mineral spirits type solvent. Didnt work. Do I actually need to remove the finish before installation? If so, do I need to remove from the entire rotor, ie hub mounting area etc? What should I use to remove it.
Is the grey substance an anticorrosion protectant ?
Thanks and regards
farrukh

1994 E500 53K miles - triple black
1995 E320T 60K miles, Starmark, E500 suspension upgrade

[Fintail Fan]

Yes, you do need to remove that dull grey finish before you use your new rotors, as that is an anti-rust protective coating. If you don't remove it first, you will damage the rotors and clog up your pads. To remove it, just spray them down liberally with any brake cleaner spray; no scrubbing should be necessary. If in doubt though, just ask the parts person at your local MB dealer. Also, you don't have to clean off the whole surface, just both sides where the pads touch the rotor, though a little overspray won't hurt.

1962 MB 220SEb Sedan 189,000
1963 Vespa VNB4T 125 motor scooter 11,500
1992 MB 300TE 4Matic Wagon 137,000
1995 Subaru Legacy AWD Wagon 98,000

[jgl1]

The grey coating prevents corrosion and is impervious to organic solvents; it does not need to be removed before rotor installation. The coating is removed by the action of the pads contacting the rotor; no rotor damage will occur nor will the pads become clogged by this coating.

M-B switched to this coating several years ago and released an S.I. stating that the coating was not to be removed.

[daddiojiggy]

i'd like to know

[Gilly]

jg1 is correct, there is a service info bulletin as jg implied. Also speaking from lots of experience, I never remove the coating and never have had a problem.
The previous material they used for rust protection, which looked like kind of a clear/blue paint, did have to be removed, not the current coating.

Gilly

[RPM55]

I agree that the coating does not need to be removed. You will have some brake vibration/pulsation until the coating is worn off so dont be surprised and think something is wrong.I have installed many of these rotors this way with no problems.

thanks all.
given the rather limited amount of time I have, Im glad I didnt screw that one up and have to redo it... :-)
best
farrukh

[Fintail Fan]

(Oops, goofed and did this reply as an original post, sorry for the confusion as a result.) Anyway, perhaps you all are right in your respone to fhmajid, however when I purchased new rotors for my '92 300TE from the MB dealer a couple of months ago, I was told specifically by them, unsolicited, to be sure I removed the grey coating before I used the rotors or what I said in my earlier post would result. If I were you, I'd call or visit your local MB parts department and ask them, to be absolutely sure. Maybe my guy was wrong, (thus I am too), but I don't know why he would've said that if it wasn't necessary.

[Gilly]

I can't complain about parts guys too much, I know they can be a great help. If a parts guy gave you the info, it may be dated info, ie relates to the previous type of coating.
No harm will come if it is removed. In the shop, where we are striving to make good time on a repair, if we are told we don't need to remove it, by all means we will not, we are "losing" time if we do.
If however you are nervous and want to remove the coating for some reason, here is what I have found:
Usually for some odd reason, one of the rotors will have the parts sticker on it (part number, etc). almost always it is on the contact area of the rotor. This of course should be removed. To remove it I soften the paper and glue with brake clean and scrape it off with a single-edge razor blade. The gray coating seems more than happy to come off as well. I would say if I really wanted to remove the coating I would try to scrape it off with a single-edge razor blade first, and if it seemed like it was unwilling to come off with just the scraping I would use a little brake clean as well. The rotor is very hard steel, the razor blade shouldn't affect the contact surface in the least.

Gilly

[csnow]

Just wanted to add that...
Many aftermarket rotors do have a coating that needs to be removed prior to install.

This varies, however.
The ATE rotors I put on last had an enclosed warning note that the coating should be left intact, while the generic detailed instructions said the coating should be removed.

[mushedroom]

i got power disc ATE rotors and it says specifically on the box do not remove protective coating