W124 E320 C - Vibration through bodyshell

[MotardMan]

All,

This problem has been apparent since I bought the car, but was not on my priority list of things to do, as I assumed it was wheel balancing.

Well, I have had the wheels balanced, twice, and still the vibes are there. They are worst at 30mph where the car will actually wobble your fat! They reoccur at 70-80mph, and then again at 120-130mph. Ahem, allegedly.

I'm sure it is not wheel balance, the rims do not look dinged or dented, and the balancing would have detected a wheel with too much run out or deformation.

Before I make a wild guess at what else could be causing this, can I have your guesses please?

 

[MotardMan]

No-one? Oh.

 

[bigasotonuk]

Hi,
Have you looked at the propshaft joints, this can cause vibration through the car.
Theres a rubber doughnut joint that wears.

 

[MotardMan]

No, good point, and my first thought. I'll get it up on the 4 post next week and check it out. Thanks for that.

 

[kth286]

Prop shaft and joining dougnuts is a suspect area.

Also have a good look at all your tyres for wear, and I mean all across the width of each tyre.

I guess however the wheels have already been removed from the car for balancing, but was that just the front wheels or all four, as the rears can cause the problem.

I mention the tyre wear because if the tracking and camber are out it can cause this vibration at certain speeds, as I had this problem myself before I changed the wishbone, which caused the track to go out when the car was driven, but was OK when the car was static on it's wheels.

That is one reason why Merc stipulate a spreader bar in between the front wheels when tracking our generation of cars. The bar exerts a force on the wishbone bushes equal to that when driving.

I guess you know that on rear drive cars the front wheels get pushed apart when driven as opposed to front drive cars where they get pulled towards each other at the front of the front wheels.

So, on the Merc any wear on the inside edges often indicate that the wishbone bushes have worn and need replacing as the wheels are being pushed out too much when driven.

 

[wireman]

If it is your donuts (mine was just the same as you describe, but worst on uphill) make certain sure that the engine mounts are in good order or they will fail again in next to no time due to missalignment.

On my 124 the engine fan sat a little low in its cowl before the mounts were changed, now it is spot on in the middle.

 

[mebobster]

what is mentioned above seems right, but from my experience i have discovered worn link rods (bushes), and believe it or not, faulty or the wrong type of alloys/wheels! dont know if that helps?

 

[Juddian]

Mebobster may have a point, among the numerous sets of wheels for our now downsized fleet of 124's, i am using a set of ankaa wheels off a 211 for the winter use (8 x 16), have had these wheels on the 320te before and they set up a similar vibration to the one you describe (both cars now).

Both cars are/were fine on the other tyre/wheel combo, so these wheels which look perfect apart from salt corrosion are the problem.

A thought, could you borrow a set of wheels off a mate with a similar car to see whether that could be the problem for you, could be a very quick elimination of that cause anyway.

 

[MotardMan]

How odd. The vibes have now gone. I'm wondering if it was a lump of mud on the inside of the wheel, which has now dried as we have had no rain for a couple of days, and fallen off?

In a way, I wish I had found something mechanical to explain it, but the issue is now gone. Thanks again for all the input.