Larger bumps in road cause violent steering shake
 

Hey all,

I have a quite concerning issue that I noticed a few days ago. If I am driving over say 40 MPH and I hit a bump in the road like going over a train crossing, the front end and steering wheel shake violently from side to side. It stops when I hit the brakes. Everything under the front end looks OK but I really don't know much about front suspension and steering; especially on MB cars. I am at a loss here. The only thing I know that is not right on the suspension is the nut on the passenger side shock is not tight against the shock mount. It is tight but there is a small gap between the nut and the washer.

Any ideas?

The problem has happened more than once.

I would inspect the Idler Arm Bushing first. It can appear to be ok when static but movement of the steering wheel and the play will be evident.

Another possibility are ball joints which will display a lot of wobble when weight is removed from the front end, such as going over a large bump.

Are you feeling any "knocking" in the area of your feet when going over uneven surfaces, such as a speed bump?

Thanks for your reply SD Blue. The steering feels tight and there is no slop, play or wandering. I don't notice any obvious knocking when I go over a bump but I'll take it out and listen when I go over a bump.

When a similar situation happend to me on other Vehicles is was always something was loose like worn Ball Joints, Tie Rod joints or so on. My other cars did not have Rubber mounted Control Arms so on the Mercedes you have to be included. The Upper control Arms have a tiny Ball Joint on them.

Do you have abnorml pay in your Steering Wheel? If so there is an adjustment for that.

Is there any abnormal Tire Wear?

Basically you need to jack the Car up and do some inspection to find the exact Issue.

Also I removed my Steering Damper over 4 years ago and have been driving with zero issues. So I do not think that would cause issues if it was not working.

Unless parts are disconnected and dragging on the ground, the front end will always "LOOK" ok. Not much special about MBz suspension compared to many others. Inspection will typically require lifting to check for play at each wheel. Grab at 9 and 3 (With respect to an analog clock) and again at 12 and 6. Any play at all, look for where it is coming from. May require a second person to move back and forth slowly and deliberately. Put hand on each joint until you find the play.

To inspect bushings and ball joints you may need a prybar or similar to leverage one part from another. Any play at all is bad.

The wobble you describe is serious. There has to be a component in desperate need of replacement or several that are nearing the end.

Go to a front end shop for a free estimate. Explain you may or may not wish to put money into the car and just want an idea what they could do for you repair wise.

Then decide if you want to tackle it yourself.

Advice: If you have a pro check it out, look it over yourself first, see what you find, then see if they find the same. This could go a long way to building your confidence.

Most repairs you can do yourself, even a basic alignment.

I'm pretty good with fixing most other things but I have not had much experience past replacing brakes, calipers and struts when it comes to front end work. The steering doesn't have any noticeable play in it. The steering wheel is clocked a few degrees off but I'm guessing whoever installed a gasser cluster in my car did that.

I'll check the tires for wear and the wheels for play and let y'all know what I find.

Let me know if you think of anything else to check.

Thanks!

OK, there is some inner wear on the inside of both tires. It's not bad...yet. The car probably needs an alignment. It tracks straight on flat pavement, though.

I didn't notice any clunking or banging when going over bumps or dips in the road during my lunch break trip.

Wheel bearings on the way out can cause what you described. I would take it to a suspension shop as recommended and have them show you what they find.

That's what I thought the first time it happened but then I quickly said no, they would have to be completely shot and I don't have any whirring or grinding noises coming from the wheels. I guess it is possible for the bearings to be bad and not make much noise. Is this something I will find when I jack the car up and test the wheel for play?

They can loosen before completely failing or making noise. Once raised and secured, wobble the top and bottom of the wheel and check for play. Should be little to none. You could also wobble the front and rear of the wheel to check for tie rod issues.

Checking ball joints is a little more involved but can be done at home as well.

Your choice on the Alignment.
A few people have had an Alignment done and a few months later their upper or lower Control Arm Bushing rotted out.
If something needs to be replaced you will be doing another Alignment.

I cant remember if inner Tire Wear is an issue with upper or lower Control Arms.
That info should be below:
Repair Links
http://www.peachparts.com/shopforum/forumdisplay.php?f=82
http://www.peachparts.com/Wikka/DoItYourSelf

I had a friend move the steering wheel side-to-side with the key on, engine off while I looked under the car. There is a clunking sound coming from the driver's side. I noticed a ball joint near the center of the car was moving but the clunking sounded and felt like it was coming from closer to the wheel, maybe even from the upper area. I don't know what the steering components are called but I will have to take pictures when there is more light out. I won't be driving the car anymore until I can get this figured out. It scared the crap out of me on the highway today when it started to wobble for no good reason at 60MPH and didn't want to stop wobbling until about 35MPH. I hope I make it home alive.

OK, I finally got some time during the day last night to check my wheel play. On the driver's side wheel, I got some play in the 3-6 o'clock test. the 6-12 o'clock test showed no play at all. It looks like the ball joint coming off the steering stabilizer is moving before the steering stabilizer does. If I apply more pressure to the test, the stabilizer will move but at that point I am moving the all the gear. Does this result sound plausible? What is that ball joint called so I can order a new one?

Thanks.

http://www.peachparts.com/shopforum/diy-links-parts-category/142397-suspension.html

Here is the 'skinny,' on your question about suspension components and replacement. Its not quite as personal but a little research and you'll have a resources without waiting on answers.

Here's the easiest way to describe it that I can come up with:

Tie Rod - connects to wheel spindle, one joint up and one down, LH and RH

Drag Link - connects LH and RH side, both joints up

Steering Dampner - connects between structure and drag link

Idler Arm - RH pivot point, (mentally picture the steering box on the opposite side of the car, i.e. British) has short Pitman Arm