Drive Train

Vibrations at High Speed

I had a high speed vibration last year. I did alignment and balance to no avail. Then I was told
that high speed vibration normally comes from rear tires. Since I had already had the rear tires
balanced, I thought I might "see" the vibration. So I jacked up the rear, put jackstands under the
rear lift points, started the car, put it in gear and took a look. Guess what, I could see my
differential jumping up and down. This was due to a bad inner CV joint.

I got a used half shaft from Dave Roberts and the vibration is gone. I also had a noisy rear
bearing on the same side. I recently replaced the bearing. I couldn't tell you which one caused
the other to fail, but I'll guarantee there was a relationship between the CV failure and wheel
bearing noise. If you jack the car up and put it in gear, BE CAREFUL. That shaft can catch a
piece of clothing and you'll be kissing the Weissach rear in a micro second.

Good luck,

Joe Rausa '89 S4 (smooth and quiet - except of course when you stomp it)