Vibration In Body

[rmmagow]

1983 300D 187000.
While out for a drive today, my wife commented that there seemed to be a vibration coming from the bottom of the car. At about 50/60 mph one can feel a vibration in the drivers side arm rest and a little in the passenger seat. I recently raised the tire pressure to 34 rear 32 front for various reasons. I accelerated to 70 mph (it a looooong drive), slipped the tranny to neutral and the vibration remained. Could this be just too much air in the tires or should the center drive shaft bushing be cheked? How is the drive shaft bushing checked? If it needs replacement I'll do the pair of flex discs too. When removing the driveshaft is it important to mark it in relation to how it was attached originally, i.e. is the drive shaft balanced while in the car? Is the bushing, flex disc replacement project a ridiculous undertaking laying on the ground? Is it more than say, $750.00 to have it done at an indy?
Hate to farm out work but 30 degrees on the ground for a few hours I'll never move under my own power again :-)

Thanks for any advise.

[psfred]

Check for vibration at the drive tunnel at about the rear of the front seats. If you feel vibration here, it's almost certainly the driveshaft, and I would expect it to be flex disks. Usually the center carrier will be worse on acceleration or deceleration, on coast it will disappear sometimes. If the vibration is centered somewhere else, it's not the driveshaft.

Raising the tire pressure can cause a bad tire to vibrate more -- check for "snaking" treads or blisters on the tread, and spots more worn that others.

Flex disk replacement doesn't require separating the two halves of the driveshaft, but center carrier does. Mark before pulling them apart, Benz doesn't use a blind spline like Volvo does (very nice, impossible to get it wrong as it will only go together in the correct spot). Clean and use a paint marker, and allow the pain to dry before pulling them apart, you will be very unhappy if the marks get wiped off somehow.

Peter

[David Speed]

Symptoms of my center bearing support failure was a low speed 'flapping' noise that ceased at ~ 20mph........and there was quite obvious movement with rocking the drivehaft by hand........your higher speed vibration probably has a different cause.

I replaced my centre bearing with my 1978 280CE's rear on stands.......would have been easier up on a lift or in a pit....R & R my one piece SS exhaust was probably the hardest part

I marked everything with typists white out.....flex discs to tranny & diff and shaft splines.....figured it couldn't hurt to put everything back the way it was...........filled one of the spline grooves that lined up with a cut-out slot with paint...and marked the slot.........as psfred says look after your markings.....apparently one spline out is enough to cause serious vibration

If you tackle this......even just the flex discs.....you will need to be able to loosen the shaft nut.........46mm if I remember correctly

Pic of the 'special tools' I used ........the adjustable plumbers wrench is what I used for the nut

[84300DT]

back in august my car also developed a nasty vibration which only got worse -very bad at highway speeds.. so much so that on one trip i turned around and parked it!
turned out front tires were badly worn out and made worse by
being also seriously out of alignment. check that first! new rubber and an alignment cured it.
good luck.