legacycentral bbs

Well folks I have a problem.Although, thanks to you all you guys I do have the facts . From the information gathered I have a couple of choices for my 91 Legacy turbo that still doesn't have a working auto transmission!

I can put in a trans that has a 3.9 rear diff, the problem only legacy turbos and WRXs have that diff (as far as I know) both exspensive new and rare used.

Although, what if I put in the rear diff from a legacy L AWD I have found then the trans from it? Would it work and could I do it my self?

Also if anyone knows of or has a used trans from a Legacy turbo or WRX that is for sell, I'd like to know.

AFAIK the WRX does NOT use a 3.9 rear diff. Its a 3.544 with a 1:1.1 gearing in the center differential

AFAIK the WRX does NOT use a 3.9 rear diff. Its a 3.544 with a 1:1.1 gearing in the center differential.

I know the L transmission would work, but are the axles the same?

first of all your 91 should have a limited slip rear differential.
what is wrong with your transmission. if your differential is fine I would not replace it. 91's were rare in the way that they came with an lsd.
I will be selling my 94 5spd transmission with diff's, clutch, fly wheel. ss, and everything as soon as my 6 spd comes. it has 55k miles on it and has had neo synthetics ran through it. it is a really good tranny. just thought I would mention it. thanks, kelley.

ciper, are you speaking of the 02-03 usdm wrx. I think they are
3.90 gearing. same as the legacy turbo's.

Two things......

The 92-93 n/a legacies with auto trannies have 3.90 gearing as well as all the turbo legacies.

Ciper is correct.....The WRX uses a 1.1:1 stepper for the rear final drive ratio.

What it accomplishes is, it gives the WRX more FWD power bias.

If you have a 3.900 final drive reduction in the front

The rear you have a 3.545 rear diff and a 1.1 stepper. That gives you a 3.8995 reduction in the rear. It is essentally a 3.90 reduction.....but the front has just a slight edge on it.....so the car will act more FWDish....

here's an excerpt from the WRX FSM's.