Center Diff Question

[Inlinesicks]

I believe my center diff is locked up due to massive resistance in the drivetrain when making low speed turns, it feels as if I am holding the brakes when I pull in to a parking spot. So my question is, if I continue driving it like this what will happen, if the center diff breaks will it damage the transmission or will it just lose power to the rear wheels, or will the diff never break and it will just be more stress on the rear end?

[Subiman91ss]

well im not sure about the center diff in this trans but i do know you have a limited slip rearend.. you could try changing the fluid in it so see if that might be the problem.. you can also change your trans fluid to see if that helps.. maybe you have a leak

[Inlinesicks]

well im not sure about the center diff in this trans but i do know you have a limited slip rearend.. you could try changing the fluid in it so see if that might be the problem.. you can also change your trans fluid to see if that helps.. maybe you have a leak

Yeah but I believe they are both VLSD's which means if they are bad a fluid change wouldn't make any difference.

Is there any way to test the center diff? Like maybe jack the car up and spin a rear wheel and see if the front ones turn also or something like that?

[PhyrraM]

Automatic or manual?

I'm guessing automatic. Search here for "duty cycle C" (IIRC)

[Subiman91ss]

edit...... these manuals do have a center VLSD.... it just doesnt work if there is a break in the system

[PhyrraM]

The center diff on a manual has a viscous coupling. It is not designed to transfer 100% power and slips alot and eventually fails if asked to do so. It is used to balance traction and power when both front and rear have some traction.

The automatics have a direct connection to the front and a clutch-pack that proportionatly engages the rear controlled by a duty solinoid. When the solinoid fails you get either no power to the rear or the locked condition the OP is experiencing.

[Subiman91ss]

thats good to know.. it sure didnt feel like it when the axle broke

[Inlinesicks]

It is a manual, I have driven it before with the rear driveshaft off briefly so I know it works like that, can I do that for the time being until I get a new center diff? I feel like driving it now with the diff locked up is going to damage the rear end or axles.

[PhyrraM]

If it's a manual, and it seems to drive with normal-ish power with no rear driveshaft, then you most likley have a locked up center diff. Continued driving will wear out, or break, parts in short order unless extreme measures are taken to avoid medium to sharp turns.

Assuming your center diff is already toast, and gear oil isn't pouring out of the driveshaft hole, I don't see a problem trying 2WD for a bit. The trans neeeds a rebuild ASAP.

[Inlinesicks]

If it's a manual, and it seems to drive with normal-ish power with no rear driveshaft, then you most likley have a locked up center diff. Continued driving will wear out, or break, parts in short order unless extreme measures are taken to avoid medium to sharp turns.

Assuming your center diff is already toast, and gear oil isn't pouring out of the driveshaft hole, I don't see a problem trying 2WD for a bit. The trans neeeds a rebuild ASAP.

Thanks I think I'll try the 2wd option for now, what cars have the same center diff, I assume 91-94 Legacy any others? It has to be out of a manual because the auto's have a different center diff right?

[PhyrraM]

IIRC, all the 5 speeds up to about '97 or so should have compatable center diffs and viscious couplings.

[Inlinesicks]

IIRC, all the 5 speeds up to about '97 or so should have compatable center diffs and viscious couplings.

What bout GL's? I remember reading somewhere that the GL center diffs will work and I know there are a couple late 80's GL's at the junkyard but I don't think there are any manual Legacy's.

[Mister Anderson]

More like 90-01 transmissions. They changed the case in 98(?) to a 10 bolt pattern but it still bolts up to our engines. Subaru also made them stronger (they are essentially a WRX case in comparison). I recently rebuilt a 2001 Impreza transmission with 92 parts. The pinion shaft, input shaft, gears, xsfer case ect. There is some differences in the syncros. The inner diameter on the newer syncros is larger than the old and so is the teeth. If you have access to a local pick-n-pull a xsfer case is fairly cheap. It's also easy to install. I have plenty of pics of the the inside, outside and everything else if you need them.

[Alphius]

Mister Anderson, are you sure about the center diff interchangeability between Phase 1 and Phase 2 transmissions? As I recall, the transfer clutch is different and isn't a direct swap between them without also changing other parts.

A GL/Loyale transmission will not work since none of them had a 5-speed with a viscous center diff. They were all either selectable FWD/4WD or full-time AWD with an electronic center diff lock (rare).

[Mister Anderson]

I used the phase two transfer case and transmission case but used the phase one gear set and shafts. If it works one way it should work the other way. The shafts are identical between the phase one and phase two. The bolt patterns and even the bolts are the same between transfer cases. Now the hockey stick (shift rod) will most likely have to match the transfer case as there is slight differences in them. Reverse selector is welded on in the phase two. In the phase one it is removable.

[Alphius]

OK, that matches what I had thought. So if he wanted a Phase 2 transfer case in his Phase 1 transmission case he would likely need additional parts, if it's possible at all.

I think the best route is to try to stay in the '90-'98 period anyway, which as a bonus should be cheaper and easier to find anyway.

[jamal]

From searching the internet you need the diff out of a phase 1. You could probably use a later one if you swapped the transfer section but I don't know for sure. Matt Monson or Phil would know.

[Inlinesicks]

From searching the internet you need the diff out of a phase 1. You could probably use a later one if you swapped the transfer section but I don't know for sure. Matt Monson or Phil would know.

Yeah I'm definitely going to go with a phase 1, the only problem is finding a Subaru in a junkyard in southern california lol.