W116 Front End Wobble ?

[GreaseMonkey]

Any clues on this one?
My '75 280SE would in theory (of course only theoretical because I don't break the law do I?) start a front wheel 'shimmy' between 110kph and 120kph.
The wheels and tyres have all been balanced and alignment checked, no play at wheel bearings either, so?
Shocks maybe? What excatly does a steering damper do?
I don't mind rebuilding the whole front end if I have to, as it is going to be a full-on restoration eventually, but I would like to know the cause.
Any hints?
Chris M.

 

[Styria]

Hi Grease Monkey, there are quite a number of components that can prove troublesome as far as the front end is concerned. If tyres and wheel alignment are within tolerances specified, you may wish to look at the following:

1)Tie Rod ends and particularly drag link.
2)Steering coupling, although it would be noisy and clonky
3)Steering damper - only perhaps
4)Suspension Dampers.

Generally speaking, a steering specialist will be able to smartly tell you what problems you are likely to have. Regards Styria

 

[John S]

A front end shimmy is normally caused by an out of balance wheel and or slack in the system. As you have had that checked, are you sure it's front wheel shimmy and not a tail shaft vibration?

 

[GreaseMonkey]

Front wheel shimmy, a very noticeable vibration transmitted up the steering column between 110 and 120 kph.
Tie rod ends were my next suspects, I will get it up on stands and have athorough inspection.
Can anyone explain exactly what the steering damper is there for?
Surely if all other parts were good there should be no variance between movement across the front wheels, so what is it 'damping' ?
Chris M.

 

[TJ 450]

Worn lower control arm bushes are causing a similar problem on my 450. Have you checked your rims for flat spots?
The steering damper simply damps the movement of the steering in exactly the same way as a shock absorber does on a steel sprung suspension setup. If the damper is not functioning I suspect that you will be experiencing the full "wobble" not a damped version of. It would not be a possible cause of the wobble.

Tim

 

[GreaseMonkey]

Thanks, I will check the lower control arm bushes at the weekend, and if there is a problem with the rims, I have a set of genuine bundt M-B alloys to replce the non-original copies currently fitted, the tyres are good, so when I get them swapped over and rebalanced I should notice if there is any difference.
As I said, I don't mind changing everything, I reckon once it is apart for one bush, I may as well do them all at the same time. When I get the SLS rear-end parts re-fitted I want it to ride like new.
Chris M.

 

[John S]

Today I was amazed to read in a 1960 magazine that Mercedes use the steering damper to help prevent front wheel shimmy, the writer claimed that Mercedes had told him this when he asked why they used it. Does anyone know if this is actually true?

 

[Oversize]

Another old one. I seriously doubt this is true. The damper just absorbs vibrations being transmitted into the column, thereby increasing driver comfort. I suspect the main reasaon for a damper is to reduce bump steer... If one end is disconnected, it's easy to tell if it's faulty as there'll be no resistance to compression or rebound, or it'll be intermittent.