GTP Rotor Coating Question

My question is about the coatings on the GTP rotors. Picked up a supercharger over a year ago from the junkyard with the hopes of eventually using the rotors. Pulled out the rotor pack today and was at first disappointed in the condition of the coating on the rotors. After cleaning them a little, I'm not sure what I'm looking at. There is a fairly thick black coating on parts of the rotors. Underneath, there is a very thin very smooth silver grey coating. Did they use mulitple layers on the rotors or is that just carbon buildup? If its carbon, its pretty tough and on there pretty good. The rotors I've seen in pics always looked like they had a black coating.



I can tell the grey silver underneath is a coating because it chipped in a couple tiny places and bare metal is exposed.





I can't remember the exact year of the GTP since its been over a year, but I'm guessing late 90's or early 2000's, if they were even made then. I guess my question is, are these any good?

Yes they are still good. If you overdrive them, that will speed up the flaking.

Justin

So is that black layer just carbon buildup then?

if you cleaned them you might as well not use themit will be more trouble than its worth. If you overdrive them it will blow the coating off of them and by removing the black carbon off of the rotors it will flake off even easier. Best advice is get another set that are black and do not clean them and dont overdrive it.

STEVE29 said:

So is that black layer just carbon buildup then?

Click to expand...

Yes, the GM 3.8 is very bad at this. Requires cleaning TB, intake and several other parts due to the design, but that engine lasts forever if properly maintained. 275,000 on mine.

I used Throttle Body cleaner before, not brake or carb cleaner, with success to clean carbon off of the rotor packs to not damage the coating. The set I cleaned this way was ran at 20% OD for quite a while in a ported 94 blower I used, and when removed for the AR the coating was still intact. But like everyone else has stated, once they start to flake its a matter of sometime when all that coating will end up in your intercooler.

Well should I try to clean the carbon off, or just let it be? I'm kinda leaning to just leaving it on there, would that cause any problems.

Just leave it on there.

Justin

read alot on this

Leaving the carbon on there will actually help the rotors seal thus performing better.