My after retirement hustle is rebuilding all Mazda 5 speed RWD transmissions including TII, FD, Miata, B2000, and B2200. In my opinion an 80 trans is not worth rebuilding due to two primary issues. First is the lack of replacement shift forks and second is lack of a replacement 5th gear needle bearing. If you're a purist who wants to stay with the 80 gear set you will likely need to find someone to repair your worn out shift forks. Contact me and I can help with that process. A better option, if you want the same gear ratio as the 80, is to find an 81 to 83 S2 RX7 trans to rebuild. These transmissions are not only stronger than the 80 but new Mazda factory shift forks and synchros are readily available. For the S2 (or any RX7 NA trans) to fit in your S1 you just need to swap the tail, the three shift rod dogs and the 80 bell housing if your car needs the top transmission switch. Top switches are only found in the 80 RX7. If you purchase a transmission repair kit only buy the bearing and seal kit and not the ones which include aftermarket synchros. Buy your synchros from a Mazda source. If you want an even stronger transmission go with an 85 or later. In late 84 Mazda improved the internal main drive gear bearing making it less prone to damage and failure. The strongest NA transmissions are the 89 S5 vert and coupes and 90-91 verts. These will also bolt directly into your S1 if you remove the vibration damper and swap the tail, shift rod dogs and plastic speed-o gear. The speed-o gear in the S1, S2, S3 is a 5 tooth and in the FC S4, S5, it's a 6 tooth.


https://cimg9.ibsrv.net/gimg/www.rx7...21d767da6f.jpg

That's quite a stack of transmission housings there. I assume your comments above include the 79 Rx-7 5 speed in with the 80?

Cool info on the transmissions. I'll have to look into that.

Just a quick update: The rattling has now been remedied (the clunk when I shut off the engine too). It ended up that it was the exhaust, the cat to be specific.
https://cimg2.ibsrv.net/gimg/www.rx7...962ae3f48b.jpg
Not much left in there.

Anyways, as of yesterday I'm running an RB header to a Magnaflow 14 inch straight through res, ending with whatever muffler was put on by the PO - it seemed decent enough. The car is a little raspy for my tastes (at least from inside, although it sounds real good from the outside). All in all it's much better than before and noticably more responsive so I'd say I'm happy, even though my neighbors certainly aren't.

I'm looking into doing a S5 or S6 alt swap, but that might still be a little ways out - I have another thread that the alt swap info is in. I've also since installed a relay kit for the headlights which has reduced the symptoms, although sometimes they do still dim. Alt bearings are also audible while driving so it does need to happen sometime soon.

Thanks for all the help, and I'll probably return with some transmission decisions sometime in the next month or so.

You would think so but no. In 1980 Mazda changed from using 10mm bolts to retain shift forks and shift dogs to using rolled pins. However, the 79 and 80 cases are essentially the same. If you can pick up shift dogs from an 80 or a B2000, B2200 you can swap a later gear set into the 79 case.