What the Heck is this vibration?
 

On my 97 E320 (37k miles), once I am driving at constant speeds. I feel and hear a vibration from the driver side floorboard all the way to the A pillar. Steering wheel doesn't shake. Motor smooth. I think it has something to do with the driveshaft or flex discs. Just this week I changed the entire driveshaft on my 300E. It made a click just when you hit started moving. What the hell is up with these driveshafts? Also I hear and feel a whirring noise under my feet just when I turn on the car and start driving. Is this sound normal.
01 s600
99 s420
97 e320
96 sl600
89 300e

Vibrations and noises are VERY difficult to troubleshoot long distance, only having a textual description to go by.

As far as the driveshafts in these cars, they are actually quite reliable. The reason for this is the fact that there is no up and down movement of the rear differential yoke as there is in most cars without independent rear suspension. The most common problem is the rubber flex discs that deteriorate with age. Most likely you could have replaced a flex disc rather than the entire drive shaft.

Sorry I can't be more helpful.

Good luck,

On my 300E, I really changed the driveshaft and bearings. But on the e320 Im going crazy. I suspected the driveshaft but I wasnt sure. If it is the flex disc, will the mechanic be able to test it while it is on the jack.

Yes, you just have to get under and wiggle back and forth to see if there is any play. These usually fail due to age, and these cars are starting to get a few years behind them now.

Good luck,