After replacing the trans mount on my W123 I notice that at low speed I have the sensation that a rear tire is flat or goinf flat. I can't imagine that the mount could have been installed in such a way as to missalign the trans? BTW tires are all new as well as motor mounts and engine shocks (replaced several months ago--so evidently none of these tiems would be a contributor). I appreciate any suggestions.

By replacing the transmission mount, you changed the angle that the driveshaft runs on. You might read my post about vibration that I put up last night.

Since you're vibration is occurring at slow speed, you are dealing with a different Gremlin than did I, but it should be good food for thought.

In a conventional, solid axle car, a misaligned driveshaft shows up as slow speed vibration.

Also, I'm pretty convinced that the vibration beginning after changing the transmission mount is no coincidence.

Hope these thoughts and this information is of use.

Have a great day,

Loosen the bottom bolts on the tranny mount and idle the engine for a few seconds, out of gear. This will shake the tranny back on center. Tighten while engine is off.

You didn't drop the center bearing mount did you?

Even if you didn't, check it for flex -- you shouldn't be able to pull the driveshaft sideways or down very much in the center bearing carrier. If you can, the carrier has gotten soft and needs to be replaced, it's allowing the driveshaft to "orbit" at low speed/high load conditions.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!