Do some 12A rotors have a anti-scuff coating?
 

I just tore down a 12A and while cleaning the rotors I found they had some type of coating along the edge of the rotor just outside of the side seals. It appears to be some kind of plastic material and the only purpose I can think of is to prevent scuffing against the side housings.

I didn't notice it until I had scrapped a lot of it off so now I wondering If I ruined the rotors. Will they be ok without this coating?

My prior engine building experience is with 13Bs and I have never seen this coating.

yeah they did have something on them, nobody knows what it is, and they seem to have discontinued using it at some point, it'll be fine without it.

it seems to be something that takes up the space between the rotor and side housing, which should lower unburned HC's slightly.

the other coating that is interesting is the 2009 Rx8's had some black coating on the rotor faces to keep carbon from sticking

Thanks!!

i know the S1 Renesis seemed to suffer from a disproportionately high level of failures that got linked to carbon buildup, but ... really, Mazda? really? you waited 'til just about the end, to decide something like that would have been a good idea? [insert facepalm]

... and at 5 years or younger, i'm guessing it's a bit early to judge how well it works just yet.

J9fd3s, do you have any specifics on what kind of material it is?

i think they might have had to see what broke, before they really got after fixing it, but yeah not exactly "speedy"

it is too early to tell if it works or not, the 09's seem to have less random failures, but the bell curve is ALWAYS at the 6-8 year mark, and we're not there yet…

no info on what the coating is, its black in color, and goes on the rotor face. no mention of it in any of the literature *shrug*