Mercedes: vibration, e55 amg, worst case scenario

Question
Hi Robert,I have a 2001 E55 AMG with 78,000 miles on the clock when i got the car 2 years ago it had done 64,000 and after a couple of thousand miles i started to get a shimmer when i first started off in the mornings which i thought was wheels out of balance but had them many times but no better,over the coming months this got worse.Up to date the local Mb dealer is as much use as a handbrake on a canoe they said it was wheels and charged me £125 to balance them and it was still there.It is now at a stage that when the car is cold and gets to 40 mph to 60 mph the car vibrates very bad but goes after about 60 but and here is the thing that puzzles me most when you have done about 20 or so miles this almost goes compleatly,but if you power it from 40 you don't feel it vibrate until you slow down to 60 back to 40 i do hope you can solve this for me as this is the only car that makes me smile every time i get behind the wheel regards Richard.

Answer
Richard,
A vibration felt through the center floor of the vehicle can be caused by driveshaft flex discs, which crack and shred, causing excessive driveshaft movement. Not repairing these can cause damage to the driveshaft center support bearing, or, in the worst case scenario, damage to the transmission or differential.
Another possibility is the independent suspension drive axels. Is you have a bad bearing in these joints, it can cause the symptoms.

I would jack up the vehicle, place it on four stands. Or, better yet place it on a rack. Place the vehicle in neutral have a helper hold one rear wheel and I would grab the opposite wheel at the three and nine o'clock position. Gently rock the wheel back and forth. Listen and watch for excess play in the drive line.

Individually I would also check the front wheels for too much play or a bad wheel bearing.

Hope this helps.
Rob