Jon,

Don't make me take out the n00b stick...

https://www.rx7club.com/1st-generation-specific-1979-1985-18/identify-these-rotors-708362/

 

the later rorors have a "N" stamped on the rotor face

 

Damn.. yup so they're not S3 rotors. Looks like I'll have to get my hands on a fairly accurate scale to doubly confirm exactly what they are.

As I said the entire rotating assembly is going to be rebalanced anyway, so it's no big deal which rotors and counterweights I have since they'll balance the whole shebang. Plus, I'm going to need to get a counterweight since I'm going lightweight steel flywheel, so at least now I know what I'm looking for.

Too bad, I was kind of hoping to use the lighter 83-85 rotors in my "Ultimate Streetable 12a" build...paying to have them lightened is just beyond my $4k build budget.

Jon

 

I will try to find the N in my set...

just in case

 

oh, just one thing

didnt the chamber on 78/80 rotors had a different shape? like 13b rotors?

 

I can almost guarantee you that those have been glass bead blasted.. DO NOT PUT THEM IN A OVEN! I did that with a intake that i blasted to powder coat them.. The glass thats almost certain inside the rotor will turn into a slurry and be almost impossible to get out..

I would put them in a bath with diesel or kerosene and let them sit there for a while. Then scrub them with a household brush (like the one you do the dishes with). If you have a paint gun, fill it with thinner, and spray them down. Then compressed air. Repeat if needed.

 

I wouldn't have purchased those rotors. But since you have them, I wish you luck.

 

I've used blasted rotors before. There's nothing wrong with it as long as they are cleaned really well afterwards. There are also different types of media that can be used. I'd never use sand to clean a rotor but walnut shells (I'm serious!) would be fine. Some media is meant to clean. Other is meant to do more. I wouldn't have blasted the bearings or stationary gear faces. I always pressed mine out first (bearings) and then used new bearings later. The gears I always just masked off really well.

 

I didn't realize they were blasted when I saw them on e-bay...

Too bad it costs so much to have RB snap-ring a gear in there, or I'd just have the stat gear part replaced along with the rotor bearing. Then there'd be zero contact between the rotor's blasted surface and anything inside the engine.

Cool, so you've had no binding issues with the apex, side or oil control seals binding in their slots because of the near-microscopic matte finish the blasting gave it?


I'm hesitant to use these in my "Ultimate 12a" build... But since the worst I can conceive of happening with them is seal stickage, I think I'm going to run with these anyway and see. If a seal sticks, it's not the end of the world - a soft seal kit and a new set of rotors and I'm back in. Though re-clearancing all the seals would suck... And if it somehow had an effect on the stat gears that could be fatal...

Gah, I'm going to have to think about this one really seriously. You never know though, there may be nothing wrong with using them, since we haven't really had someone come out and say "I used rotors like that and forked my engine".

I've still got many parts to collect, so I've got plenty of time to think. Right now I've got rotors and an e-shaft. I've got irons that I can get ground down and re-nitrided and passable rotor housings, but I may end up replacing those with new or closer-to-new parts.

Jon

 

I've never had issues at all with seals sticking. The finish isn't as rough as people make it out to be. I've always used new seals and have clearanced them. It's always worked fine for me. 2 engines built this way. Yes it was 2 cars!

 

Jon, you don't need to worry about a seal sticking. Just take the time to clearance them and they will be fine. .002" is your magic number.

 

Nice pics...

 

Cool, will definitely do. So it's set then - I'll run with these rotors and we'll see how it goes


Leesha - thanks for the comments. Whereabouts in Canada are you?

Jon