'91 350SDL weird suspension shake
 

I am trying to figure out what is going on with my 350SDL. I already put new tires (needed them anyway) and they are ballanced. When i am driving at 45mph plus, it will be smooth, but all of a sudden one of the tires will start to wobble and the steering wheel will shake a lot. at first i would release the throttle, but now i realized that if i slightly turn the steering angle (cant do it very much in a single lane) the crazy vibration will cease. so it happens mostly just when going straight, but if i turn it slightly it goes away.

What components am i to look at? The shop only said i needed rear shocks when i brought it to them. they did not seem very knowledgeable. can this be ball joints or tierod ends worn out?

Cheers.

Front wheel bearings worn? Lower ball joints worn? Loose lug nuts?



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If it is a violent low frequency "rip the steering wheel out of your hands" wobble, replace the steering dampener and inspect the center link and idler arm closely in addition to all other steering and suspension parts.

Good luck!!!

Would be great to put the car on lift and run it to that speed, see if there is anything visibly loose. That's the easiest test without touching anything. But it may not show this way, so could be a false negative.
Sounds like some joint is bad.

How many miles? If its over 200k it needs everything in the front suspension.

True.

Plus, it's 30 years old. He needs everything and more probably. It's a very, very, long list.




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Full front suspension rebuild plus flex discs and rear shocks, swaybar bushings and endlinks would be what I'd do. Its not that hard but around $2k worth of parts.