1991 Legacy, AWD: Okay, I will try this from a different slant, without all the confusing history. I have a bearing noise comming from my drive train area. Not the tires. Not the wheel bearing, but sounds like that. Heard louder when turning left, but heard all the time. Sounds like it is in the front end of the drive train, maybe more to the left side. Getting so bad that I am afraid to drive the car. any ideas? Thanks!!

Well, I think I found the answer to my own problem. On the pre 1995 Subarus there is a bearing housing and axle seal on each side of the front differential. These housings cover the bearings themselves. The bearings are pre loaded....in other words, replacing them is not a job for a tranny novice like me! I have no intentions of pulling the front differential and rebuidling it. Perhaps I can R&R...remove the differential I have and install a junk yard variety. Will check on prices tomorrow. Has anyone else run across this before? Is there any problem with switching front differentials? I know one cannot swap crankshafts...but I am an engine person myself. I have no clue what complications might arise from switching differentials. Anyone? Thanks!

I believe if you set the gear backlash with the proper amount of shims, you should be ok. However since the case will change, the previous shim amount from the old case, and the new case may not be correct.

Are you talking about the shims at the bearing housing (on the outer edges of the differential)? I know there are quite a few shims/spacers inside a differential, which is why the things scare me. Or are you talking about a shim where the differential matches up to the tranny? Maybe I should just take the car out and shoot it. Thanks for the reply, though. i wasn't sure anyone was going to answer me.

I was talking about the shims on the bearing housing.

 

Where are the shims inside the differential?

Oh, I don't know. All I remember from school is that everything has to be spaced just right or it doesn't work. Is there any problem with using the shims from the "new" differential? When I pull the axles from the old one, I was planning to just toss the old shims from the old bearing housing and use the "new" ones so that they match the "new" case. Will this cause any problems? Thanks.

I assume we are talking about the 4EAT, right?

 

If so, yes you can swap the front diff, I just did this to put 3.9 gears in a replacement trans for my '92 SS. Some things to consider though...

 

The gears are matched sets and you should really swap the pinion shaft too, even if its the same ratio, but you MIGHT be ok if you dont.

 

Not only do the bearing caps set the preload on the the diff/output bearings but they also adjust the ring gear right to left in the housing, this may need to be adjusted to get a good mesh pattern/backlash, but you should be able to preserve the preload if you move one in the same amount you move the other one out.

 

You may need to re-shim the pinion (whether you change it or not) to get the proper pattern/backlash.

 

There are some differences in the internal parts from year to year, I note some more info here:

http://bbs.legacycentral.org/viewtopic.php?t=21482

 

Subaru's tolerances seem pretty good, in my case I kept the shim that was with the pinion shaft and the pattern and backlash were good without adjusting the diff bearings. Been running smooth and quite for about 2000 miles now.

 

Here's a look inside

 

 

 

 

 

More pics here:

http://photobucket.com/albums/v204/All_talk/Subaru/4EAT/

 

Gary

Okay, I have come to the conclusion that I am in way over my head on this one. thanks for the advice, but I think I will have to just give up on this mission. I think it is beyond my level of expertise. thanks for the pics.

Due to case differences and everything, you really need to check the backlash when you swap everything.

 

BTW, Gary....great pics!