1990 Legacy AT ft differential failure

[amuller]

I hope I'm posting in the right place here.

 

The differential has failed as above. (Gear teeth in the oil so I am sure.) Only about 120,000 miles on this car.

 

People seem to laugh at the idea of fixing a car this old. Can anyone advise as to an approach to fixing this? Can I fix the diff without getting into the transmission itself? What years of transaxle will swap in?

 

Thanks.

[ericem]

stick to a 90-91 n/a trans. The gear ratio needs to be the same. I would fix it, grab a good used trans and don't worry about it. Really weird the diff went. These cars have very well built drivetrains.

[amuller]

Thanks very much for the response. All the info I have suggests differential failure isn't common on these cars.

 

Questions: Why do I need to stick to a 90-91 transaxle? Is it a matter of ratio, or....?

 

Are there a lot of different ratios in these years?

 

Do I need a transaxle from a wagon or will a sedan one do?

 

Around here, (Delaware_ most yards don't seem to be keeping cars this "old."

 

Alan

[idosubaru]

post in the parts wanted forum here, might get a score. check craigslist and ebay. it's not out of the world to find something really cheap or free on craigslist. like a wrecked car, blown motor.

 

sedan/wagon doesn't matter.

 

the main thing is making sure the final drive ratio matches. in which case you could swap rear diffs if you found a good deal and wanted to jump on a good deal.

 

i think you could use almost any 90's cable clutch trans. some 96+ models (like the GT's) had a hydraulic clutch set up. but 90-94's should definitely work (keeping in mind the final drive ratio). they'll all be 3.90's or 4.11's.... i think most will be 4.11's.

[Gloyale]

double check that one of the CV joints in your axle hasn't exploded.

 

I have seen them break, but stay *attached* and in the cup under the boot.

 

The symtoms present basically the same.

 

Clunking at idle in gear, and grinding when shifting into park. Hesitation to accelerate until the rear end kicks in fully and bucks the car forward?

 

If you really did see chunks in the diff, that is what is most likely is. But if it was just a fine metalic powder, and you have a broken axle, then you're diff is fine.

[amuller]

Thanks much for all the info.

 

This car is an auto. I'd be willing to swap in a five-speed If I ended up with a car to get the stuff from. In my limited experience, these jobs tend to grow and grow and grow as more and more differences turn up. Can anyone tell me what all is involved?

 

So you are saying I can use a later-than-'91 trans if I pay attention to the ratios? Where are they marked on the units? How late can I go?

 

Thanks!

 

am

[idosubaru]

So you are saying I can use a later-than-'91 trans if I pay attention to the ratios? Where are they marked on the units? How late can I go?

 

direct swaps go like this:

 

90-91

92-94

95-98

 

with some searching here you'll be able to narrow that list down a bit. for instance, find someone who has swapped a 90 and 93 then you know (which i'm pretty sure it true) that:

 

90-94 are interchangeable.

 

of course you always need to keep the final drive ratios in mind. i'd avoid the 90-94 legacy turbo's. you probably won't see many anyway but those trans tend to have more issues.

 

spend some time searching and it'll all shake out for you. TONS of good info over the years on here.

[idosubaru]

i searched and didn't find much info on using later 95+ transmissions in earlier models. i only looked for 3 minutes, so you could search some more or start a new thread with a more precise title "will later year transmissions work in 1990" or something like that.

[Gloyale]

90-94 are interchangeable.

 

 

 

Not really.....

 

90, 91 legacy had 4.11 final ratio

 

92-94 legacy had 3.90 final ratio

 

That is why 90,91 models feel *quicker* and more powerful.

[idosubaru]

Not really.....

yes, really! i was answering his question, not making a universal statement:

So you are saying I can use a later-than-'91 trans if I pay attention to the ratios?

he's aware of the final drive issue, so the answer becomes yes.

 

well actually it comes down to semantics by "pay attention to" does he mean "are there any matching final drive ratios" or "i'm willing to swap diffs if i find a smoking deal".....so we need him to clarify since the former is "No." and the later is "Yes."

 

at least...i think later stuff works, i asked you in an older thread if you knew for sure the 93/94 stuff will swap into earlier stuff and you didn't answer (you probably didn't see it). do you know if they will (minus the final drive issue)?

 

he can make this work, like swap rear diffs, run FWD, etc if he wants options.

[Gloyale]

 

at least...i think later stuff works, i asked you in an older thread if you knew for sure the 93/94 stuff will swap into earlier stuff and you didn't answer (you probably didn't see it). do you know if they will (minus the final drive issue)?

 

 

Oh yeah, an older or newer (up to early 98) trans should bolt in and even have the same connectors from what I have seen.

 

I just wanted to make sure he knew there is a gear ratio difference between 90,91 and the 92-94

 

Trans ID is one of the bains of my existance right now.

[idosubaru]

awesome GL, thanks! i've been wondering that about the earlier gens. i know the engines dont' play well but didn't know about the trans. that's good info, i couldn't find it searching here.

 

Trans ID is one of the bains of my existance right now.

awesome! i saw that recent thread.