DrewG

Hi all,

I am looking for a little bit of help diagnosing a noise that is occurring on my white '91 C4. My wife and I were on a 100+ mile trip the other day and during the last mile or so, the car developed a bad rubbing/grinding sound, but only underway (yay! not an engine problem). We got it home without any drama and the very next day I replaced both the front diff fluid and the transmission fluid with Redline 75W90. There was some metal fuzz on both magnetic plugs as pictured below. The fluid in the front diff was basically crystal-clear, while the tranny fluid was a bit dingier, but nothing out of the ordinary.



The sound does occur in forward gears as well as reverse. I have posted 2 videos to the youtubes in hopes that somebody will know it just by the sound. Before anybody bashes me, I realize that it is dangerous to have the car on jack stands and on, in gear, but I felt it was the only way to get a sense of where the sound was coming from:


In the video that shows the exterior of the car, I noticed that only 3 out of the 4 wheels were spinning forward. I figure that is simply due to the sensors 'feeling' wheels slipping, but would be interested to hear if this is an issue.

Thanks for any input.

Drew

Black Sea RD

Hi Drew,

In answer to your email, it does sound like the classic sound of bad torque tube bearings.

How many miles are on the car and have you had any work done to the clutch lately?

Noises within the torque tube travel, but you might be able to pinpoint it better with a mechanics stethoscope.

First step would be to check the tightness of the clamps at both ends of the torque tube drive shaft.

If you have a shop you use regularly and trust, we would let them help you with the diagnosis.

We do have our Super Bearing products to rebuild your torque tube if it is the culprit. Although it can be done by you or your shop using our products, these torque tubes are a bit fussy and we would recommend sending it to us for the rebuild.

Best regards,