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98 Legacy L AWD 2.2 Wagon Auto Shuddering while turning


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I have done some googling and am finding some mixed information.

 

I am driving the car home tomorrow, so I want to have everything ready so i can fix it all at once.  I noticed when turning it feels like the rear wheels are locked together (like the posi unit is shot, for example).  The tires are all the same size, so that is eliminated.

 

I read that changing the fluid and adding GM Posi additive (which i have, because i have a 96 trans am) to the rear AND/OR trans??? fixes it?  This is the part that confuses me, as I have no idea how the AWD subie system works.  do I put that posi additive in the TRANS along with the ATF fluid AND in the rear along with the gear oil?  

 

Thanks!!

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As far as I know, when a LSD fails, the clutches wear out and that in no way will cause the rear end problem you are describing. The rear just becomes an open differential. 

 

May want to drain the rear and look for metal flakes.chunks. You may have damaged spider gears but that is fairly uncommon. 

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I also had the shuddering you speak of. I added the "mouse oil" or GM rear end lube to the tranny fluid, and it cleared the problem in less than a mile. I was told to do a lot of figure "8s" with the car to get it to loosen up and was not required. And all this information came from a Sube Tech. Car went to 315000 miles before the head gaskets went. Bottle cost me 11 doll hairs.

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So to completely answer your questions:

 

I added the mouse oil straight to the transmission fluid. Did not change the fluid at all, just put the gear oil right with it. I did this at 176k miles and never changed the AT fluid and as I said was still functional @ 315k miles.

 

I did not add the mouse oil to the rear end diff. 

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Fixed right rear caliper, replaced rear brakes. Found left rear tire has a flat spot. Could maybe cause the "torque binding?" Its bad like can't even do over 55 lol (vibration from tire).

 

Also found the bottom parking shoe spring on right side is hitting abs wheel? It hits hard when making a right but doesn't hit when making a left. Bad bearing?

Edited by ThoR294
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It sounds like you are finding your problems. I would say from the way you explain it that it very well could be a wheel bearing. Bearings on these cars can be tricky to diagnose. First try jacking the wheel up off the ground and see if there is any side to side play or noise when you spin it. If not then driving it for a while and feeling of your hub is getting hot or not will tell you as well.

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  • 2 weeks later...

It sounds like you are finding your problems. I would say from the way you explain it that it very well could be a wheel bearing. Bearings on these cars can be tricky to diagnose. First try jacking the wheel up off the ground and see if there is any side to side play or noise when you spin it. If not then driving it for a while and feeling of your hub is getting hot or not will tell you as well.

Welp heres an update.

 

The grinding noise out of the right rear was the backing plate.  The bottom was rusted and hitting the rotor.  I smashed some of it out and cut some of it away.  It is mostly gone now.  It is KIND OF there, but gone.  Bearings are fine.

 

Put 4 wheels and 4 new tires on it.  I can now safely go over 40MPH  :blink:  lol.

 

I did a trans service, the fluid was sooooooooooo brown.  I put 4 quarts in like a moron, so it was overfilled, and I added 3OZ of GM posi additive with it (spoke with a seasoned scubaru tech, he said he does it all the time to cure it).  I drained it down till it was properly filled.  :D   The shuddering has toned down A LOT.  It is only there at extreme turns.  So maybe keep flushing it?

Edited by ThoR294
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The rule of thumb on a trans oil change is drain/fill 3x with some driving in between. Then add whatever magic elixr you want to try. Its been found that the flush has cleared up the torque bind you're suffering in a lot of cases.

 

Subaru awd in a nutshell...

Duty c solenoid controls awd. Power on, center clutch unlocked. Power off locked. Speed sensors control how often the clutch cycles. The clutch itself is a pack of discs, and plates just like the ones in the trans.

 

My 2cents. Flush the trans 3x and put the fwd fuse in. This will let the clutch unstick if its gonna. If it still shudders, add the friction modifier. Then leave the fuse in till the shudder stops.

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The rule of thumb on a trans oil change is drain/fill 3x with some driving in between. Then add whatever magic elixr you want to try. Its been found that the flush has cleared up the torque bind you're suffering in a lot of cases.

Subaru awd in a nutshell...

Duty c solenoid controls awd. Power on, center clutch unlocked. Power off locked. Speed sensors control how often the clutch cycles. The clutch itself is a pack of discs, and plates just like the ones in the trans.

My 2cents. Flush the trans 3x and put the fwd fuse in. This will let the clutch unstick if its gonna. If it still shudders, add the friction modifier. Then leave the fuse in till the shudder stops.

Makes sense. So keep driving it and flush it with the fwd fuse in? How will I know if the shuddering stops though :P

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Do tight figure eights in a parking lot. You'll feel the bind, and you'll know when its gone.

 

If I put the FWD fuse in, the binding stops.  The binding is only there if the car has the AWD enabled (FWD fuse pulled).  are you just saying to leave the fuse in when I drive it, and only pull the fuse when i do a drain/fill?

Edited by ThoR294
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If its not binding with the fuse in i read wrong lol

Leave it out while you do the flushes. I've heard it can just unstick immediately, and sometimes it can take a little time. On the flip side, it may not fix it at all. In that case you can pull the clutch and rebuild it fairly simply without pulling the trans.

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If its not binding with the fuse in i read wrong lol

Leave it out while you do the flushes. I've heard it can just unstick immediately, and sometimes it can take a little time. On the flip side, it may not fix it at all. In that case you can pull the clutch and rebuild it fairly simply without pulling the trans.

Oops :). The first flush made it sooo much better. Before it binded REALLY bad when I cut the wheel like 1/8th of a turn. I couldn't even drive the car. I had put it in FWD mode to drive it. After the first drain/fill, I am now able to drive it in AWD mode. I can feel the shudder on most 90 degree turns, but it is no where near as bad. I will try a few more drain and fills and try more posi additive.

 

Good news on that I can rebuild just the clutch packs without re-doing the whole trans. Any recommendations on where to get the parts/write ups on how to do it?

Edited by ThoR294
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do multiple drain/refills, that often fixes them. no filter or additive needed.

 

external filters started in 98 or 99 - so yours may or may not have an external filter.  have you checked?

 

the internal filters are pointless to replace, i wouldn't waste your time there. they aren't filters - they're just screens.  they can't really clog and if they do you have far more internal damage than a filter change will ever mitigate. 

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