I just replaced the bad transmission in my 1990 190E 2.6. The job went very smoothly and was pretty easy. While the new trans shifts and generally performs wonderfully, I have a very, very slight vibration between 40 and 45mph. I paid particular attention to making sure the front and rear driveshaft sections were aligned properly per the markings. Is their a particular orientation for the front flex disk relative to the trasmission and driveshaft? I could find no documentation of such but I am at a loss as to the cause of this vibration. When I say slight, what I mean is nobody but me can detect it. It's there but presents at very low frequency and intensity.

Any tips on where to look next would be a great help.

Thanks,

Sam

The front flex disc has to be installed in the correct direction. Should have "Diese Seite Zur Gelenkw" on one side. This side faces the drive shaft.
Did you tighten the drive shaft spline nut with the car jacked up or on the ground? If tightened with the suspension hanging, the drive shaft will be under some stress when driving which can give a slight vibration. Also check the condition of the hanger-bearing rubber support.

Yup. I tightened the driveshaft clamp nut with the suspension hanging.

Dropped the exhaust again and loosened it...jumped around in the trunk for a minute like a rabid monkey to settle everything, the torqued it down. Smooth as silk again.

Tranny from Sun Valley shifts like new, BTW.


Thanks again.

Sam