Up in the air, my rear driveshaft barely spins. Is this normal?

[Alekos]

I was unable to find an existing thread about this. I am hoping you guys can maybe weigh in on what's going on.

So we had all the wheels off the ground the other day to diagnose an odd rumbling sound when the wheel is turned any amount at all to the right. We put the car in gear and noticed the front driver side wheel was the only wheel moving with speed. The front passenger and rear driver wheel were barely moving. The rear passenger wheel had no movement.

When we took it out of gear, the front passenger-side wheel actually started turning backwards! I've been scratching my head at this. What's going on?

[D.Martijn]

You mean just spinning by hand right?
I do remember really having to pull/turn the rear driveshaft quite hard when tightening all the bolts/nuts at the rear diff.
You are just fighting the friction of the viscous coupling in the transfercase..

The front passenger side wheel turning opposite direction is just the open diff that's doing it job.

[Alekos]

You mean just spinning by hand right?
I do remember really having to pull/turn the rear driveshaft quite hard when tightening all the bolts/nuts at the rear diff.
You are just fighting the friction of the viscous coupling in the transfercase..

The front passenger side wheel turning opposite direction is just the open diff that's doing it job.

I should've clarified. I meant we had the car running and in gear with all the wheels off the ground. A local mechanic told me its normal when there isn't a load and means the t-case is working.

[E30andy]

I should've clarified. I meant we had the car running and in gear with all the wheels off the ground. A local mechanic told me its normal when there isn't a load and means the t-case is working.

The only way to tell if the T-case is working is the jack test. What you are describing sounds normal, only one wheel spinning while all four are up in the air. I noticed the same thing on my (first) ix and panicked and posted here about it and was reassured it did not mean the T-case was broken.

[packratbimmer]

Jack test is best because it is a dynamic test as stated above. If your VC is outright BAD, test by having both rear wheels down + one front, and the car in reverse or 1st gear. If the wheel up in the air spins freely with no resistance your VC is completely toast. If it turns with steady and substantial resistance it might be good - find a place to confirm with a jack test.

[AWD_E30]

Jack test is best because it is a dynamic test as stated above. If your VC is outright BAD, test by having both rear wheels down + one front, and the car in reverse or 1st gear. If the wheel up in the air spins freely with no resistance your VC is completely toast. If it turns with steady and substantial resistance it might be good - find a place to confirm with a jack test.

Do what packratbimmer says here^. A good drivetrain should have a minimum of 3 wheels spinning when in the air. Since the front differential is an open diff, you may find the front left or front right wheel spins faster than the rears if extra resistance is on one front wheel and not the other. A good center viscous coupler (the one in the transfer case) will force the front and rear driveshafts to spin at the same speed when up in the air. A good viscous coupler in the rear differential will force the rear wheels to move at the same speed and in the same direction.

Alekos, based on how I'm reading your description, I would say you have a bad rear viscous coupler and possibly bad center viscous coupler. I would also guess you have some brake drag occurring or some other resistance at the slow/stationary wheels. Keep us posted on what you find so others can learn if they have the same symptoms.

Good luck!
-Devon

[Alekos]

Do what packratbimmer says here^. A good drivetrain should have a minimum of 3 wheels spinning when in the air. Since the front differential is an open diff, you may find the front left or front right wheel spins faster than the rears if extra resistance is on one front wheel and not the other. A good center viscous coupler (the one in the transfer case) will force the front and rear driveshafts to spin at the same speed when up in the air. A good viscous coupler in the rear differential will force the rear wheels to move at the same speed and in the same direction.

Alekos, based on how I'm reading your description, I would say you have a bad rear viscous coupler and possibly bad center viscous coupler. I would also guess you have some brake drag occurring or some other resistance at the slow/stationary wheels. Keep us posted on what you find so others can learn if they have the same symptoms.

Good luck!
-Devon

thanks for the help, Devon. I now know after the Jack test that my center VC is bad. No movement at all from the front wheels when the rear is up and spinning.

[AWD_E30]

Bummer Alekos! You know how to get ahold of me if you decide you want to go the rebuild route.