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2000 Subaru Outback shimmies and shakes at low speed

My outback, only after warming up for half an hour makes a lot of shaking at extremely low speed turning (either direction) like in a parking lot. It’s as if the outside tires are turning at the same speek as the inside. I had the rear differential drained and refilled with an adative, it did nothing. They want to flush the transmission now (never been done) but I am worried about another 150 and damage to the transmission. Any suggestions?

Unfortunately, the damage has undoubtedly already been done to the transmission–in more ways than one.

The problem that you describe is the classic symptom of a failing center viscous coupler/clutch pack, and has nothing to do with the rear differential. The reason for the failing center viscous coupler/clutch pack is operating the car without closely-matched tires (failure to rotate the tires every 5k or every 7.5k miles, and/or different sizes/different brands of tires). The only cure is to replace this component to the tune of…probably about $700-$800.

Regarding the transmission, problems with the center viscous coupler/clutch pack do wind up being transmission problems also, so it is very possible that the transmission has been negatively impacted by this other situation. However, if you have really been driving this car for 10 years without servicing the transmission, trans problems are sure to happen anyway.

Trans fluid should be changed every 3 yrs/30k miles (whichever comes first). Failure to do that will result in trans failure any time after 90k miles, and is pretty much of a sure thing by 120k miles. As always, maintenance (such as tire rotation and transmission fluid changes) is far cheaper than the mechanical problems that result from lax maintenance.

Even though it is rather late in the game, you might want to take the car to an independent trans shop for a proper flush. When many shops do a flush, they wind up damaging the trans. A good independent trans shop will change the filter first, prior to doing a flush. Personally, I would just have the trans pan dropped and cleaned out, and have the trans filter and fluid changed a.s.a.p. and then I would repeat this procedure in about 5k miles.

Get a Subaru specialist shop to work on the center viscous coupler/clutch pack. If you are lucky, you will be able to get away with both the flushes and the repair for about $1,000.

Sorry for the bad news.

Thank you very much, news is good even when it is bad. The only thing I would like to add is the tires have always been matched and rotated on schedule and Trans fluid has been checked (not changed but toped off) every 30k. Are you supposed to change it every 30 or just check it? Also this is a manual transmission.

I am willing to spend a $1000 on the car but not 3,000, is there any way to know if the damage from the center coupler has spread to the trany without 1st spending 1,000?

Thanks a lot. VERY helpful.



You have done everything right. There is no need to change the transmission fluid every 30k miles on a manual transmission. It gets inspected.

Your manual transmission is absolutely fine likely. So no fears there.

A manual transmission has a part called a viscous coupling that allows slippage between front and back wheels. This may be the culprit. You cannot change its fluid as it is a sealed unit. It is very rare for this unit to fail even on manual AWD Subaru’s with a few hundred thousand miles.

This likely is not a $1000+ repair whatever the case. Changing the manual transmission fluid will have no effect on the issue but is prudent. The price is no where near $150 to change manual transmission fluid. It is not much gear oil in there and drain bolt just like your engine gets undone. They fill from the top.

Well, as usual, full details up front would have been helpful.
The good news is that a manual transmission does not need to have its lubricant changed every 30k miles. I had assumed that your trans was an automatic transmission. So–I doubt that any harm has come to your transmission.

Also, the setup for torque transfer is simpler on the manual transmission models.
You have a viscous locking center differential that may well be cheaper to replace than the clutch packs on the automatic trans models. However, you do need a mechanic who is very familiar with Subarus to work on this part of your car. With any luck, the repair will be cheaper than either I or Andrew had anticipated.