FormulaBUff

I'm wanting to get a limited slip into my 1980 first gen. I'm curious as if I can just swap in a rear end from a different model or just the third member or what? Also, wondering what gearing you guys run in the rear end? Are there any good aftermarket lsd's or are the mazda ones decent?

Rx-7Doctor

iTrader: (13)

You can swap a complete disk rearend if you want to do that or just a LSD from a 81-83 model.
Note; mid year in 83 they went to a larger flange so if you got the later 83 LSD you would also need the driveshaft from that year.

7aull

iTrader: (2)

I think you need to upgrade the brake soft line back there too, because the thread pitch for 79-80 brake lines was coarser than the 81+ system. I bought the Racing Beat Stainless Steel lines, which come in a version that includes using an 81+ LSD diff, so that rear SS line has the coarse thread on one end and the fine pitch on the other. Maybe others out there that offer just the rear line intself?
Stu Aull
80GS
w LSD/Disc rear end

RX7KENN

I bought the wrong body kit, It was made for a 81-85 RX7,
and I have an 80RX7, I think it should only need minor mods,
depends how indept you want to change it.

680RWHP12A

wrong again...
if the 83 rear end has the larger driveshaft flange then its a big bearing, big axle rear end so it WILL NOT FIT in a 79- early 83 rear end!!

if you just want a posi rear i would swap in the early pumpkin 81-early83 from a GSL model

to do a disk brake swap you would need a complete disk rear end with the brake softline like the gentelman above stated plus the parking brake cables too as those are different..

sgieldon

Not sure about this? But would'nt you also have to change out the Master Cylinder and Brake Booster ie Converting from Rear Drums to Rear Disk.
It's been about 15 years ago since I did this with a 80-84 change over and I remember having to change out the lines and the HandBrake Setup, but I can't remember If I also had to the above?
I hate getting older!!!!
And the answer is???
sgieldon
steve

Siraniko

iTrader: (13)

The 81-85 brake booster is larger so keep the SA brake booster.

IF You have a complete donor:
Swap everything (except for the brake booster) such as brake lines, master cylinder, front supension/brakes and rear disc to disc. The only thing that you will need to fabricate is a bracket to hold the brake line (where the soft and hard lines meet) as the SA's front brake lines are shorter and are secured in the wheel well.

For FB swap only (front suspension/brakes along with complete rear disc brakes) , you need the "SA to FB "soft" brake line kit.

For "GSL 3rd member swap only," 81-82 GSL. I have seen a few 83 GSL 3rd members with large axle flange that came with large axles so not all came with small axles as others have mentioned. Again, this is for CALI cars only and I have short piece of small axle (I personally cut = spline end about a foot long) that I bring with me during junk yard runs.