1991 diffs and transmission fluid change

[10wrxing]

Hey guys,
So, I have a 91 Legacy AWD 2.2 (non turbo) auto.

As far as I know, neither diffs nor the transmission fluids have ever been changed.

I'm a little leary doing this because of the age.
I know on some old cars, they don't like having their fluids changed if it's never been done, and you get problems.

Anyone have any input on if they think I should bother?

What do you guys suggest running in them?

This is just a DD car, never driven hard.

I've done a little research, but finding it hard to find the info on the first gen Legacy's fluid changes.

I should mention that what is really prompting me to ask is that I've noticed when making fairly hard turns at low speeds (IE: turning into my driveway), I'm getting a grinding noise. It seems to only do this after lengthly drives. As if maybe the drivetrain is heating up and causing this? It also acts like it wants to stop the car.
I haven't been able to pinpoint where it's coming from, but it has been suggested that I change the diff fluids. I figured the transmission should probably be done at the same time? I know if it was manual it would share the diff as well. So it just makes sense to me.


Thanks in advance!

[TurnNburn]

How many miles are on your car?

For your sake, I hope that the fluid is not original.

Honestly, if its making noise already then the damage has already been done. Changing fluid may help longevity but its just a matter of time before it pushes up daisys.

When you say it feels like it wants to stop the car, do you mean when you are turning that the car feels like its slowing down, or all of the time?

[10wrxing]

Car has 140,000 kms on it now (87,000 miles)
It only does it when turning tight. Otherwise it's fine.
Car drives just as good as a brand new car.

[TurnNburn]

wow, pretty low miles. But fluid also degrades over time, not just from miles. Sounds like a Duty C solenoid going out. Search "duty c solenoid" and see if that sounds like the same symptoms you have.


*edit* This is a thread I started 4 years ago about this problem I had with my car. There are many like it, but this one is mine. haha

http://bbs.legacycentral.org/viewtopic.php?f=7&t=46096

[10wrxing]

I have actually read your thread about a year ago.

The main differences are I have no lights on, and it doesn't do any lurching after the car is off.

The only similar symptom is the 'binding' on hard turns.

This is the sound:
https://www.youtube.com/watch?v=do3YpKMphS4
I know you've seen this video already, as you replied to it in another thread I had about a noise when making turns (the original sound was actually the muffler, and I believe it may have been a baffle inside the muffler causing that sound and vibration).
Is that the sound you were getting?

I've tried the car in fwd and it didn't do it, but it's random, and doesn't always do it.

I've driven the car 10,000 kms (6200 miles) since I got it, and it hasn't gotten any worse.

Like I said, other than this, the car drives as nice as my wife's 2015 Lexus, or my '10 WRX....other than wind noise lol.

[Legacy777]

Change the fluid.

Your issue is likely the degraded fluid causing the friction plates for the rear drive to bind, which is what you're feeling. Changing the fluid should help this.

[10wrxing]

Change the fluid.

Your issue is likely the degraded fluid causing the friction plates for the rear drive to bind, which is what you're feeling. Changing the fluid should help this.

That's great to hear.

I found this thread:
http://bbs.legacycentral.org/viewtopic.php?t=39331

So will follow the suggestions and manual there.

Thanks!

[10wrxing]

So, I'm a bit confused on this page from your link:
http://main.experiencetherave.com/subar ... ns/102.jpg

Do the front diff and automatic transmission share the same fluid?

[mike-tracy]

Front diff takes gear oil, and is separate.

[10wrxing]

Front diff takes gear oil, and is separate.

Great!
Thanks!

[10wrxing]

Changed both front and rear differentials today.
I noticed before that the car didn't want to turn sharp turns, it would actually stop if I turned all the way to the left or right in a parking lot, trying to make a circle for example, or an 8 as suggested.

Now, after swapping out the fluid, it has no issues with either of these. It will move under idle while making a circle.

Time will tell about the noise it was making. But I'm pretty sure that should have fixed it.

Thanks guys!

[Legacy777]

Just to confirm you changed the front and rear diff fluid as well as the auto trans fluid?

[10wrxing]

Just to confirm you changed the front and rear diff fluid as well as the auto trans fluid?

Only the front and rear diffs fluid.

I'm very much up in the air about changing the transmission fluid, as I've heard and read many bad stories about people who have changed transmission fluid in cars that were 20+ years old.

It's driving perfect now, and I don't want to risk changing it and having it do something silly on me.

I did try to pull the trans dip stick out to at least check it, and it is stuck in there.
It's dropped to 5 degrees here now, so I won't be playing with it until the spring if I do decide to do it.

[Legacy777]

I don't understand how just changing the front and rear diff fluid would have any affect unless maybe the old gear fluid was way too high a viscosity. How did the fluid look when you drained it?

Do you know if the front and rear diffs are stock? The front will be open and the rear, even if it's a LSD, it's a sealed unit and fluid shouldn't have any affect on its lock up.

I guess if it's working ok now, then it may be good to leave it alone. How does the trans fluid look/smell? Is it red/pink or does it smell burnt and more darker color?

[10wrxing]

I don't understand how just changing the front and rear diff fluid would have any affect unless maybe the old gear fluid was way too high a viscosity. How did the fluid look when you drained it?

Do you know if the front and rear diffs are stock? The front will be open and the rear, even if it's a LSD, it's a sealed unit and fluid shouldn't have any affect on its lock up.

I guess if it's working ok now, then it may be good to leave it alone. How does the trans fluid look/smell? Is it red/pink or does it smell burnt and more darker color?

As far as I know, both the front and rear diffs still had the original fluid from the factory in them.
My grandfather owned the car since new, and swears neither diffs or the trans have been changed.

The diff fluid looked pretty brown coming out, the front worse than the rear. Not much on the rears magnet, but the fronts magnet had a fair amount on it.

The car was built April 1991, so if that fluid is from 25 years ago, perhaps it was caused by the fluid being old and broken down and having no viscosity left?

The only difference being the outside temp, as it's dropped now since the last time I heard the sound.
Now, I noticed before that it would seem to do this sound/feeling after a long drive.
I would turn into my driveway after driving a fair distance, and you'd hear this sound and vibration, but very hard to tell where it was coming from.

It's been just over 2 weeks since I changed it, and I've driven the car a fair amount since doing the diff fluids, with that noise and feeling not coming back since.

Perhaps I won't know for sure until it gets warmer outside.

As for the trans, I can't tell you what it looks like or smells like, as I couldn't get the dip stick off when I tried.

[Legacy777]

If the diff fluid was original, more than likely the trans fluid is original. I still think it'd be good to do a drain and fill on the ATF. But the first step is getting the dip stick out.

[10wrxing]

If the diff fluid was original, more than likely the trans fluid is original. I still think it'd be good to do a drain and fill on the ATF. But the first step is getting the dip stick out.

Once it's nice again here I'll get it off and have a look at changing the ATF fluid as well.
Car is still running like new.
Only wish I could fix the drafty windows.