91' legacy vibration?

[smith2016]

1991 legacy has a strange vibration. First a little history. The car has had a hard life. had two junk yard trans put in it. last one has lasted two years. previous owner put a junk yard rear end in it 2.5 yrs ago. The car has always a had a vibration that starts in the rear and feels like it shutters through the car to the front. I started by pulling the drive line and looking it over and had a shop check it out. they feel there no reason to replace anything. ( i figured it was a wobbled center bearing, Guess i was wrong).

 

I put only the front half of the drive line back in just to see if the vibration got better or worse. The carrier/center bearing is not the problem, as the vibration is gone when I went for a drive with just the front half installed. The vibration has gone away completely. Any ideas?

 

Will it cause a problem to drive the car as a front wheel drive with just the front half of the driveline installed? Should I put the AWD fuse in until i resolve the issue or not worry about it since the rear end has no drive line to it?

 

where to start in looking for the cause of the vibration? I was thinking the gear ratio is off and this is causing the vibration. second half of drive line? Did the drive line shop possibly miss something with the drive line? Could a Ujoint cause this much of a vibration? It feels like a wheel hop vibration.

 

Any ideas? any help would be great.

 

Thanks

[johnceggleston]

Will it cause a problem to drive the car as a front wheel drive with just the front half of the driveline installed? Should I put the AWD fuse in until i resolve the issue or not worry about it since the rear end has no drive line to it?

 

where to start in looking for the cause of the vibration? I was thinking the gear ratio is off and this is causing the vibration. second half of drive line? Did the drive line shop possibly miss something with the drive line? Could a Ujoint cause this much of a vibration? It feels like a wheel hop vibration.

 

Any ideas? any help would be great.

 

Thanks

 

you can drive it this way no problem. the fuse is not necessary.

 

there is a way to test if the front and rear diffs are the same on endwrench.com.

 

test for checking if the front and rear diffs match: (auto trans only)

 

jack up both wheels on one side of the car and put it on jack stands. (be sure to block the 2 wheels on the ground.)

mark the 6 oclock position of the front and rear tires that are in the air.

unplug the large trans elect. connector at the rear of the engine on top where it meets the trans.

start the car, put it in neutral, and release the parking brake.

turn one of the tires by hand 4 or 5 rotations.

the tape marks should end up in the same position, if they don't then the front and rear diffs do not match.

 

when you undo all of this don't forget to plug in the electrical connector.

 

tag line: diffcheck, frontandreardiffsmatch

[smith2016]

Ok, Thanks I will look into that this afternoon.