vibration....pulsing shutter - ZF problem?

Don't know if this will help, but when I had my half shafts out, I noticed that the scribed lines across the two halfs were not lined up. In other words, when they were originally balanced, a line was scribed where the two halfs come together so that they could be reassembled correctly and maintain balance.
It might be something to look for.
Mooso

Have you changed anything on the drivetrain lately?
Will

I changed over to my second set of wheels/tires recenly. They were fine when I removed them about 2 months ago. I always have a small continuous vibration - the rear view mirror shakes under load. When I push in the clutch while driving, the vibration stops.
The pulsing vibration is new....since I changed the rims/tires.
Thanks for the help!

I'm not saying what it is BUT 70mph is THE MPH that a unbalanced or a BAD tire vibrates at. I don't know why they do it, they just do. Been there done that. Don't look for Martians. Look for a bad tire. And yes they can be difficult to find.

thanks for the help and sharing your experiences. I found a loose U-joint, which I am hoping solves my vibration issue.

FWIW, loose bolts holding the u-joint flanges to the halfshafts will cause a shake. I found this by accident on a '71 during a run- one bolt of the 16 had a cracked lock-washer that had fallen out, leaving the bolt loose. 3/4-turn tightened it up and thats all it took to cause a shake under power! Since then, this shake-under-acceleration has been found on two more Panteras across the U.S with loose bolts in the halfshafts, so check to see if the bolts are tight in your car!

Did you find the problem?

I had the U-joints replaced in one shaft. Installed it last night. Let you know the outcome after my drive today.