I have a developing issue with my '99 Legacy Outback 5speed. When I am making sharp turns, I am getting a knocking/thumping sound and vibration coming from either the middle or the back of the car. The rate is speed related. It only makes this noise when the wheel is turned over 180 degrees either direction and gets worse the more it's turned. I have zero noise at any speed while driving straight or slightly turned. 

 

I originally thought that the half-shafts were going out, so I inspected them all and they all have good boots on them. Then I suspected that the rear diff was binding since it seems to be coming from the back. The diff is full of fluid and I jacked up both rear wheels and turned the wheels in opposite directions, trying to feel any binding. There was zero binding.

 

Is it possible that my center differential is binding when I'm making a sharp turn? How can I confirm this? Is there any way to fix or lessen any damage being done without rebuilding or swapping the transmission/transfer case?

 

Thanks much.

The center diff can be swapped without removing the trans...just remove the driveline and shifter assembly, and remove the rear cover on trans and center diff comes right out and can be inspected/replaced.

Thanks for the reply. That sounds easy enough. I have a few questions.

 

Does the problem I'm describing sound like it's the center diff binding up? It's intermittent. Seems like it's worse after I've driven it a long distance. 

 

Second, after the rear cover is removed, is it pretty self explanatory on how the center diff comes out? Also, how does it disconnect from the shaft leading to the front diff? Is it just a spline that slides out when the center diff is removed? 

 

Thanks again. 

didn't realize a manual. Deleted.

Edited April 5, 201510 yr by xdeadeye1

General way to check for binding is to find a parking lot and make tight circles with the wheel at full lock. If the car does it under its own power, probably not binding. If it stalls and/or needs throttle input in order to keep it rolling, that's binding and the general source of that will be the center diff.

 

The 99s have some issues with the center diffs.

 

Removal is pretty straight-forward. Pull the tail housing off the trans and the center diff just slides out. The only really tricky part is the transfer gear shaft has to slide out with it at the same time, and has to be slid back in at the same time.

Do 99 have the fed fuse? If so pop a fuse in and see if it goes away, if so it's the center diff for sure.

*fwd fuse.

*fwd fuse.

 

Not the 5MTs. Full Time 50/50 split.

 

Had a buddy's LGT do the same thing, but it was a bad front axle. Looked good/intact boot, but when removed, that thing would lockup on the inner joint on fairly sharp turns. Pop, grind, growl, good lord.

many times have read that binding becomes worse in 5spds after they are warmed-up.

 

doesn't mean you shouldn't investigate; carrier bearings, u-joints , dragging brakes , diffs or axles first.

Edited April 6, 201510 yr by 1 Lucky Texan

http://www.subaruforester.org/vbulletin/f89/center-diffs-how-replace-them-46979/

 

center diff replacement walkthrough