FB_MItch

So you can get a backstory on my 1979 RX7 GS in my build thread listed in my signature but my car finally gave in after blowing small amounts of smoke on and off it got to the point where it was blowing clouds at idle and I decided that I have to do a rebuild. I have since pulled the motor and disassembled it but now I am at the point where I need to figure out what I need to have done to the parts. I contacted Speed 1 in PA in regards to resurfacing the rotor housings and side housings and was told that it would be best to just replace the rotor housings altogether and to get the side housings resurfaced and re-nitrated. I was just hoping that I could get a few of you guys to give me your honest opinions on the parts I have and steer me in the right direction. I already plan to replace all seals: apex, side, corner, oil control rings, etc. I was also thinking I might get a street port done as well since the engine is already out. I would appreciate any help you can give me and look forward to getting this engine back in the car and back on the road.

7aull

iTrader: (2)

Hey Mitch-
With only one build (on-going) under my belt, I won't pretend to be an expert. We have those folks here on the Forum and hopefully they will respond. I think, in general, re-using rotors and E-shaft are normal procedure, assuming no mechanical damage. You note a little divot on the edge of one. I used ALL my housings on my SA rebuild (90K). The irons were fine, a test for these being - I am told - that if you can run a thumb-nail across the surface cleanly, they should be OK. Of course, mazda has a very specific technical spec for runout and surface evenness, etc that you can perform. This is outlined in the Shop Manual.
Housings are tricky. There is a certain amount of edge failure permitted as yours displays. Very common of course. If you haven't already been told, SA (79-80) housings are all but extinct, save the few hoarded here and there. So replacements may have to be FB housings, requiring (?) the related irons too. And I think even these (FB housings) are no longer sold by Mazda. We 12A owners are in a bit of pinch keeping these engines running!

If you have not rebuilt a rotary before, I recommend one of several "rebuild videos" available for about $30. Of the 3 I know of, the Mazdatrix one is excellent. Many little "gotcha" tricks it helps you avoid!

Best of luck

Stu Aull
80GS
Alaska

FB_MItch

Yeah I have noticed how hard it is to locate SA housings, and I've thought about trying to get FB housings to fit but I can't really find any of those either without spending a large chunk of money. The reason I am so weary of what I can reuse is because this is a car with 180k on it with no rebuild so these parts have seen quite a bit of wear and tear over the years and the car sat in a garage untouched for 26 years until I began to resurrect it. I do have and have been using the Mazdatrix video for the entirety of the rebuild process, it has paid for itself already in teaching me how to properly disassemble the motor. I think I will be taking a trip up to PA to Speed 1, which is apparently one of the highest rated rotary shops in my area, to get them to look over all of my pieces and give me a professional diagnosis.

TimWilbers

iTrader: (1)

Others know way more than I do. I've only rebuilt my 12a twice (the second time immediately after the first as I broke a dowel pin O-ring the first time).

A visual inspection will reveal gross defects.

Download the FSM (Factory Service Manual) for your year. Follow the link in the post near the top of this forum. With the FSM you'll have the specifications you need to help determine which parts need to be replaced.

You'll need measuring tools:
feeler gauges
micrometers and telescoping gauges
caliper
dial or digital indicator, with stand (measure wear on iron surfaces and end free play)
Harbor Freight may be your friend

My rotor housings were well beyond yours so I did find a replacement pair through this site.

My main bearings were worn and just at the upper limit of wear, so they were replaced.
My apex seals were all warped, and were replaced.
Side seals were out of spec and replaced as were the oil control rings and O-rings.
The front end thrust bearings, plates and spacers were worn (chatter marks) and replaced.
Many other things were replaced along the way as it is over 30 years old.

Good luck.

(Search "12a Rebuild" in the 1st Generation section, for my saga. I started knowing near nothing.)

FB_MItch

I actually have a hardcopy of the FSM for my car, for some reason I didn't even think to look in there for information regarding this. Regardless, I don't own any of those tools that I'd need to properly measure everything myself but I brought it up to Speed 1 and they told me my plates, rotors, and E-shaft, are in excellent shape. My rotor housings are totally shot tho so I guess I'll be looking into procuring usable ones.