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Rear differential compatibility

Posted: Wed Nov 10, 2010 2:00 pm
by MagicBus
Hello, all

I've spent weeks trying to get my '94 Legacy (2.2L NA wagon, 5-speed, AWD) running again, to no avail.

I have a lead on a low mileage '93 wagon. Seller says their mechanic told them it's on the verge of needing a new rear diff, but is driveable.

Since it needs a rear diff, I assume the '93 is AWD. I assume that if both cars are 5-speed, than the rear diff should be identical, and I should be able to pull the good one from my car for the '93.

However, if the 1993 is an automatic, than do both cars use the same rear differential, or is it different in an automatic?

EDIT - JUST GOT A REPLY EMAIL FROM SELLER - THE 1993 CAR IS AWD AND AUTOMATIC.
SO, IS THE REAR DIFF IDENTICAL, OR DO I NEED TO GET ONE FROM AN AUTOMATIC CAR?

Thanks,
Rick

Re: Rear differential compatibility

Posted: Wed Nov 10, 2010 7:28 pm
by Legacy777
The rear diff is going to be different. The MT has a 4.111 final drive ratio, while the AT has a 3.90 final drive ratio. You should be able to find a 3.90 final drive ratio if you need it. The 92-94 non-turbo AT's all had a 3.90 final drive ratio as well as the 91-94 turbo MT & AT's.

Re: Rear differential compatibility

Posted: Wed Nov 10, 2010 10:39 pm
by FlatBlack
Drain the oil and see whats going on yourself before you change the diff.

It can't hurt to check, and I'd rather see metal shavings myself before taking a mechanic's word.

Re: Rear differential compatibility

Posted: Wed Nov 10, 2010 10:53 pm
by kimokalihi
Yeah last time I took someones word on a bad rear diff it turned out to be a bad wheel bearing and the diff was fine.

Re: Rear differential compatibility

Posted: Wed Nov 10, 2010 11:06 pm
by MagicBus
Still haven't bought the car, and may or may not look at it this weekend (it's off a distance).

Drained/refilled on my '94 twice since I owned it, so can do. So, metal shavings are the indicator of a bad diff? Seller claimed a clunking, which actually suggested a CV axle to me, but said their mechanic told them it was the diff.