I_Frizzle_l

First post here, cut me some slack if I'm not doing it right, but I'd like some experienced advice. I have a 79 with a 5 speed with 82k miles, and the tranny is starting to act up, and I am looking to do a transmission swap. My criteria (in order of importance) is ease of swap, reliability, part availability, cost, and lastly strength (by this I mean im running a semi stock 12a and not pushing any extreme power lol and am NOT looking to anytime soon).

mazdaverx713b

iTrader: (91)

I would recommend replacing it with a known good 79-80 5spd trans. The shift lever is farther forward in the SA and you would be altering not only the trans tunnel but also the shift surround and dash extension if you used a later RX-7 transmission.

yeti

iTrader: (1)

@mazdaverx713b When you say altering the trans tunnel, what needs to be done? Hammering it larger? Relocating the trans mount? I'm curious so I know what I may be getting into in the far future. I understand the shifter hole is wrong. I would like to see pictures of the differences, shift hole alterations too, for curiosity sake.

j9fd3s

iTrader: (3)

with 82k on it, you should have it rebuilt. finding another SA trans would be tough, and yours is probably in better shape

t_g_farrell

iTrader: (1)

It may not be the tranny. Give us more symptoms. It could easily be the pilot bearing or low on fluid or any number of other issues and may be working just fine otherwise. In other words there may be a simpler fix that swapping or rebuilding.

Jay Davidson

iTrader: (1)

This...
...and this...
It's a manual transmission, so there's only so many things that can go wrong. Assuming the box itself isn't detonated, changing the slave and master cylinders, swapping the clutch/flywheel/pressure plate/throw-out bearing, and doing a fluid change will be less expensive and less wasteful than tossing out the whole kit-n-kaboodle.

mazdaverx713b

iTrader: (91)

If you were to swap a later transmission in, you would have to cut your trans tunnel rearward to accommodate the extra length. I'm with the above on having your trans rebuilt or replace it with a known good trans.

Also, why do you think the trans is bad? The SA trans is pretty tough and at 82k miles, unless it was run out of fluid from a tail shaft seal leak or beat to death by shifting like an animal, it should have held up very very well.

gracer7-rx7

iTrader: (16)

For a trans rebuild, Pettit, Rotary Performance, RX7.com, maybe Defined and probably spec miata shops should be able to take on the job or at maybe make a recommendation. Assuming you can't find a good local shop.

Here's a spec miata shop that does trans rebuilds on miatas https://www.advanced-autosports.com/

19-r-e-d-79

iTrader: (1)

If your ambitious you can always use an FB transmission and just shorten the shifter rod.

7aull

iTrader: (2)

Bear in mind too there is a cosmetic issue with the actual transmission cover/console in the car. Tricky to mod all that plastic! As in:
it will be a chopped mess...

Stu A
80GS
AZ

t_g_farrell

iTrader: (1)

Thatgs dependent on the FB tranny version and the SA tranny version. Not generically possible with all combos.

mazdaverx713b

iTrader: (91)

I do agree with Stu that the interior will not look right with the shifter back farther than it originally was. Also, he would need an early FB (81-83E) driveshaft as the SA driveshaft would be too long if he replaced the trans with a later trans.

sa7

iTrader: (13)

Driveshafts are the same length for all 1st gens, and the transmissions are same length. The shifter housing on the tail shaft is in different locations making the shifter sit further forward on the SA.

When I swapped to a gslse rear end on my SA, the se driveshaft worked perfectly with the SA trans.

racerx01

Pretty sure that you can just swap the tail shafts from your SA transmission to a FB gearbox and it will fit. Have seen some pictures in tech section. I did kinda of the same thing when my FB gearbox broke, and buddy had a S4 FC gearbox... he swap my tail shaft and speedo gear and we put the S4 gearbox with FB tail shaft back into my 85 FB without needing to change anything else. Welcome to the 1st Gen RX7 world.

mazdaverx713b

iTrader: (91)

You can swap the tail shaft a d shift rod. The only thing to look out for is heavy wear on the tail shaft bushing. It's a copper bushing that's pressed into the tail shaft. They are NLA and if worn can cause issues.