I'm pretty sure they are 83-85, but I need some help identifying them. All I have left from the engine are the irons.

BTW, if anyone is interested, I am selling them. Do not respond in here since it is the tech section, PM me instead.

 

3mm apex seals maybe glse rotors

 

^They're LDR rotors, not the standard MDR that the 13B uses.

Soak them in a bucket of 50:50 water and Zep industrial purple cleaner for a day, and wipe with a brush to get all the crap off of the metal, then spray with compressed air, WD40 and more compressed air, then post more pics.

 

isn't the purple harsh on aluminum??

 

Rotors are cast iron, and yes. I threw an old aluminum piston in the bucket for the hell of it, and it became porous and black, like pavement. My rotors looked brand new with no carbon/brown/varnish on them. Even though my bearings looked perfect after the cleaning, I changed them anyway.

 

Well I'll throw one thing out there : They should be 12a rotors So that will eliminate a great many choices of what they could be.

I'm going to be acquiring these from alexdimen and was wondering if there was a way to find out if they were from an S1, S2 or S3 motor just by looking at them. I'm hoping they're 84-85 rotors because that's what I already have the rotating assembly for.

And yeah, these will be home to a set of "Race Rotor Bearings" from either Mazdatrix, RacingBeat or Atkins, so alex if you've got some cleaner, soak away!

Jon

Edit: I bet if we got Jeff20b in here he could figure them out.. he's really good at identifying engine bits.

 

Well, Jeff responded in another thread that if there is a cast "N" in the combustion dish, they are 83-85. The "N" is near where the rotor will say "F" or "R" as in front or rear.

 

kind of looks like my SE ones but i think it might be the 84-85 12a

 

Damn... I've been struck by the "Search n00b" stick. I definitely should have been able to find that, had I actually bothered to do a search.

Alexdimen, any pictures of the combustion recesses?

 

Yes, pics of the bath tub's shall clarify this!

 

Thanks for the responses. They are not 3mm. It was from a 1st gen 12A. They are DEFINITELY either 81-82 or 83-85.

I did some searches and came up with nothing about identifying rotors.

Dish pictures this weekend.

 

https://www.rx7club.com/1st-generation-specific-1979-1985-18/diff-12a-rotors-front-rear-706455/

Should be 3mm if it's from any 12a engine 79-85.

 

Yeah, all 12a rotors were 3mm. They only went to 2mm in the FC 13b.

That's perfect though because those pics look 3mm, and that's what 12a rotors should be, so everything's on track.

I guess it's not a huge deal if it's 81-82... just means I'll need a different set of counterweights. I'm getting the rotating assembly rebalanced for high-rpm anyway, so no biggie.

I still want to see those pics this weekend though!

Jon

 

Not ALL 12A rotors take 3mm seals, the early twin dizzy ones had 6 mm carbon seals, lol.

 

That's true, T.

Also, besides the width of the rotor, you can tell 12A vs 13B as the 12A has an asymetric combustion dish (F rotor, R rotor), while the 13B has a symetric dish (interchangeable).

Jon is such a n00b. Actually, I just remembered that recent thread that waysrx7 posted a link to. I didn't search. In the pic waysrx7 shows in that thread, at first it is hard to see the N and the R. But if you look hard enough, you'll see them.

 

'74-'75 12As had a symetric combustion dish.

 

Yeah, should have mentioned that was for '76 on.

 

*laughs* you guys are the most "l33t" rotary geeks I have ever met.

It's freakin' awesome.

Jon

 

Looks like 83-85 12a rotors to me i think previous one's have the F & R on the middle of the combustion cup not at the top like these do

 

Looks like I just missed the n00b bullet and it caught you Jon.
At least they were nice about it though.

Well that's enough post whoring for me.

 

Oh, oops... I only checked the seal to wall clearance with the used seals that came with it... so I never measured the whole width of the groove.

I know these are 12A rotors for a fact. I personally pulled this engine from a car in the lot at chesterfield auto parts.

I've got the rotors in front of me. They have F and R stamped in the dishes. There is no N. So, that makes the 81-82?

 

Yeah, or '78 to '80. What does the front counterweight look like? Half circle or less than half circle?

'78-'82 had the same weight rotors but the front counterweight was different. When Mazda went to a lighter flywheel in '81'-82, they had to use a lighter front counterweight (the pone that looks like less than a half circle). The rotors themselves remained unchanged from '76-'82.

'83'-85 front counterweights are more of a quarter circle.

 

Here's a chart to identify what rotors you have.

http://www.mazdatrix.com/faq/rotorwgt.htm


You have to take all the springs and seals out of the rotor, clean it, and then weight it and use the chart to identify what 12a rotor you have. I just pulled my engine apart and I had no idea what was inside. My rotors came out at 9.5lbs each so I have the 83-85 rotors. My rear flywheel was out of an 80-82 12a. So there was probably a balance issue with my motor.

 

Here's the link for the flywheel.

http://www.mazdatrix.com/faq/flywheel.htm

 

I appreciate the input guys, but I've already discussed the flywheel (sold a while back) and that it's definietly either 81-82 or 83-85.

I will try weighing the rotors too and look at the front counterweight. Thanks for reminding me of that.