300SDL takes off vibration issue?
 

One of the 300SDL always gives a bit of vibration at the rear when moving from stop. Vibration is very noticeable. It happens when car first starts moving in D, 3 or 2. It does not seem to happen in reverse. It has been like this for at least 1-2 years. The car cruises smoothly after shifting and on freeway without issues. I have checked the obvious, the flex disks.

What can cause this symptom? What else should I check? Should I be worry?

Anything I can check? Suggestions, wild guesses?

Does the vibration increase with RPM / Speed or is it a steady?

Check your center support for looseness. I'm not sure if that year had a 2 piece or 3 piece driveshaft, one of the support bushings may be rotted out. That, or you've got some bushing problems. Jack up the rear and throw it on jackstands, fire up the engine and brake torque it. If your rear wheels seem to be moving in and out perpendicular to the car, your subframe mounts may be toast. Maybe have someone do the brake torque while you're under there watching everything.

The vibration only lasts during initial movement/shift. Once it shifts into 2nd, no more vibration. 2nd, 3rd and 4th has no issue and car drives very smoothly at highway speed or anytime passes 10mph. That is why I ignore it for the last couple of years. I have some time now and would like to take a look and resolve it. I hope it is not something sinister in the tranny 1st gear.

Does the SDL have a limited slip differential? Could be the limited slip clutches are releasing? My first thought would be the transmission or the torque converter, but I'm far from an expert there. My '95 124 will slip / vibrate on a full throttle launch sometimes, especially when hot, and I think it's either the transmission or the torque converter. I had plans to convert the transmission to a manual shift, but now my wife has been driving it for several months and she loves the automatic around town, so when it finally dies I'll get a rebuilt autobox.

My SDL had a similar vibration before I had the driveshaft re worked with a new u-joint and balance.

It was subtle at first so I replaced flex disks, center bearing & carrier, engine - trans - diff mounts...no joy.

I then read about u-joint notching causing vibration especially under load at low speed. So I changed the drive shaft angle pitch by putting a simple washer between the center bearing carrier and the mount area on the car body thus changing the drive shaft alignment.. low and behold much less vibration. So I added another and it cleared up the low speed and under torque vibration for another 10,000 miles.

Eventually the vibration came back (notched u-joint) so had to have the drive shaft reworked.

Found the problem. The exhaust was hanging loose. Replace the exhaust rubber loop and all is well for now.

Fantastic!
 

I loved seeing your easy fix.

Good damn thing you didn't send the drive shaft out for work first like I thought may help...lol... That would have cost me a few rounds of golf!

Thanks for posting the fix.

Had the exact same scare.... my 2011 VW Jetta Sportwagen TDI, had same rattling noise, scared the crap out of me. Found out it was the exhaust. danged 2 bolts that mounts on the exhaust system just behind the TDI motor just came off.... due to diesel motor vibrations. Going to buy bolt fastener ... and hopefully keep it on!