I have a 1980 3000CD W123 non turbo. I changed the engine with a lower mileage 617 non turbo engine. After that I have a vibration that starts at about 40 mph and smooths out at around 55 mph. I have had the drive shaft completely rebuilt. New "U" joint, bushing in the ends of the shaft. New center bearing and new flex disks. The tires only have 2000 mile on them and I have switched the fronts to the back. There has been no change to the vibration. Just to make sure I swapped out the differential. During the engine swap out, I changed the torque converter, from the old engine which had no vibration. Is the torque converter balanced with the flywheel? Does any one have any ideas? The engine feels smooth when cars is in park and raising the RPM.

I forgot to mention. When I changed the engine out I replaced the engine mounts, transmission mount, the exhaust system mount and the differential mount. Nothing has changed the vibration problem. At about 50 mph I also hear as drowning sound. If I put the car in neutral at 50 mph the droning sound goes away. But I still feel the vibration. I am about to move the trans back and rotate the position on the torque converter to a different position on the fly wheel. It's the only thing I can think of. Any help would be great.

when you removed your center bearing did you mark the 2 shafts for reassemble? this would cause a misbalance in the shaft.





the garage



8 mercedes 2 ferraris 3 porsches over 50 cars there is just not enough room....lol

When I pulled the motor and trans., I had disconnected the trans from the drive shaft. But as I was moving the eng/trans. out, I heard a clunk and it was the front of the drive shaft. I could not find any aligning marks on the drive shaft. I then found the u joint was stiff. So then I had the drive shaft rebuilt with the new center bearing at a quality drive line service I have used before. They of course balanced the complete shaft. After rebuilding the shaft I made sure there were alignment marks on both sections. So yes the drive shaft is timed right.

Had this similar scenario on a 124, a high frequency vibration starting at 38 MPH. It was the pinion angle, the front of the pinion had to be angled down a little with a shim.

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

How did you know how how thick of a shim you needed ? And where exactly did the shim go?

It was done by my indie, I think it was about 1/8" thick, he estimated it from experience. The angle can be measured but is a little involved. The shim went between the front of the differential housing and the body at the front differential mount.

Good luck!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Thanks for the info. I will keep it in mind. I am currently moving the trans back an inch or so to enable me to rotate the torque converter 1/3. I will let the forum know what happens. I am doing this because I read somewhere, that Mercedes balances the torque converter with the fly wheel and crank shaft.

1) Torque convertor balance is independent of engine, and is neutral.

2) Is the vibration a function of engine speed, or vehicle speed?

3) Was the flywheel/ring gear of the replacement engine kept with that engine, and in its original position on the crankshaft?

Yes, the fly wheel and ring gear stayed with the engine. It appears there were two sources of vibration.
I rotated the Torque Converter by 1/3rd. The engine vibration seems to have gone away. The droning noise at 50 mph is gone. Now I can identify the vibration is not coming from the engine.
I am going to try the shim on the diff. Sugar Bear suggested and see what happens.

I have added two 1/8 in. shims on the front of the two mounting studs on the differential. The vibration has diminished greatly. There is still a slight vibration. I think most people would not notice it. But I am now looking for it. I and going to add another pair of 1/8 in. shims when I get a chance. The car is definitely acceptable to drive now.
Once I add the second pair of shims I will post the results. This may be a while since the car is usable now. I would like to thank everyone for there help.