W124 vibration at high speeds (yeah I searched)
 

I get slight vibrations around 45 mph, but if I go over 70 mph, the car acts as if it will shake itself completely apart! :eek:

This has gotten worse over the years despite 4 sets of tires, a 4-wheel alignment performed during tire replacements, and several wheel balances.

I actually avoid highway drives in this car due to the excessive vibrations...tragic, since the engine runs well and seems to enjoy flat-out motoring!

I don't think it's engine speed related since the vibration seems to manifest itself at different road speeds while in 4th gear. My indie checked the motor mounts last summer and deemed them healthy.

Don't know the condition of the flex discs or other drivetrain components. Where should I start looking and are there telltale visual clues of certain worn parts?

Sure sounds like a driveshaft related problem to me.
Possibly centre bearing or flex disc?
Sometimes, having the car on a hoist & running it up to speed can give you a clue.
Maybe the old trick with hoseclamps on the driveshaft would help too.
( Only to verify or disprove the vibrations source ).

Where did u have the alignment done? - The best place is the dealer or a shop that does lots of MB's.

Are the tires feathering?

In my case, the PO had an alignment done at a small shop that didn't really work on MB. They didnt get it right and it feathered or cupped the tires. It destroyed a set of Pirellis in about 8k miles. The symptoms were similar, vibrations in the floor and steering wheel starting at 60 mph and up .

We put a new set of tires, it started to vibrate again, until a MB dealer did the alignment, It cost 110 bucks or so, but no there is not a problem.

I had a simialr problem with my '92 300TE last year. The shaking on my car became so bad that I actually pulled off the highway once and checked all the lug nuts because I thought a front tire was about to fall off. Soon after that I had the steering damper replaced and had a four wheel alignment and wheel balance, but the condition improved only marginally. It was only after I rotated the front tires to the back that the source was pinpointed; the (former) right front tire was badly out of round. I have had smooth driving ever since, (when the car runs that is!).

1962 MB 220SEb Sedan
1992 MB 300TE 4Matic Wagon
1995 Subaru AWD Wagon

Definitely check the steering damper. I knew mine was leaking and needed replacement. Then one day the front end went into a violent shimmy - nothing like I have ever experienced before. I went down to the dealer and bought a steering damper the next day and replaced it. Once the old one was off, it was clearly completely non-functional - zero damping. It's a high pressure "de Carbon" type design, like the shocks, so once it starts leaking there is zero damping. The high caster Merc front suspension needs a damper to prevent shimmy!!!

They are typically no more than about $35, even from the dealer, but less at Fastlane, and only two standard metric nuts to replace.

Duke

... a couple of questions for you. You indicate minor vibrations at 45mph, and vibrations detectable on the Richter scale at 70 mph, but what happens between those speeds ... a steady increase in vibration level?? or does it die out and come back as you accelerate to 70??

Can you distinguish whether it is at the wheel rotation speed or at a higher frequency ... such as drive line rotation speed (frequency)?

I just got my Mercedes, so I don't even the details of the driveline construction, but in other vehicles I've had nasty vibrations from worn u-joints, as well as worn splines.

Check both flex disks pronto!

Any signs of wear or out of center bolt farings in the rubber, replace. While you are at it (since you must drop the driveshaft anyway), see how much movement you can produce in the center bearing carrier rubber mount by pulling/pushing on the driveshaft. If it moves more than a couple mm, replace it (and check the bearing while you are at it).

A bad center bearing will drum floorpan horribly -- easy to tell, as the vibration will be worst right at the rear of the front seats on the drive tunnel.

As noted, a new steering damper and proper alignment probably are a good idea as well. A new damper will save the tie rod ends and drag link, too.

Peter

I actually had a nasty vibration on my 1991 300TE caused by a broken flex disc bolt.
If I recall it started at about 55 mph; it's been a while, so I'm not sure of the speed, but it was a broken flex disc bolt.

Judging by the details you provided, I can definitely tell you that your problem is bent wheel(s). Have your mechanic carefully run your wheels on that balancing machine and check for such a defect.

Wow! Lots of suggestions!

I did check each tread for abnormal cupping, etc. Wear patterns look normal.

Rears used to wear prematurely, but an alignment fixed that.

I'll try swapping rims to see if the vibration changes in any way.

Other than that, I'm scheduled to see my indie shortly, so I will have him test and diagnose as well...

Do the rims first. I bet you that's your problem. I just went through the same crap. :(

also check out these PDF files:

http://www.meimann.com/docs/mercedes/driveline_balancing.pdf

http://www.meimann.com/docs/mercedes/driveline_vibes_early124.pdf

http://www.meimann.com/docs/mercedes/driveline_vibes_late124.pdf

:sun_smile

braverichard

That was exactly my reaction .....: Bent wheel.

Haasman

My indie verified that the vibration is NOT drivetrain related...he's currently checking front end components, but thinks I should get the wheels re-balanced and the tires rotated to see if the problem shiftfs to the rear.

I will do that first and keep you updated of the results...

So have you completely ruled out having either a bent rim or an out of round tire or both?

In addition to replacing my bent wheel, I just had to replace both of my front tires because one of them was not round enough to not cause high speed vibrations.