My 1984 190d at about 40mph started to shake a little bit - you know, like the tires are out of balance. I took her to have the tires rotated and balanced. The slight shake is still there, but at different speeds - 55, 45, 60, etc. Now, while I'm driving, say at 55 she shakes a little. I slow down and get back up to 55 and she's as smooth as silk. I guess what I'm trying to say is that some times she will, and sometimes she wont. When I had the work done I just mentioned I took her back because I thought they did not get the tires in balance. So, they did it again. If its not the tires, what in the world could be causing this??

Sincerely,

Hugh

I've had the same problem at high speed and went thru the tire balancing and rotation etc. like you are doing, at the end the problem went away when I replaced the steering dampener... My 2 cents

Definately the steering dampener. Check the tie rod ends and Pitman while you're under there.

The steering dampener nor any other part in the front end can CAUSE a vibration. Bad parts can allow a vibration to be exacerbated, but only ROTATING parts can CAUSE vibrations.

The most common cause of vibrations are indeed tire related. Of the tire related causes, the most common cause is when the tire store kids do a static balance rather than a dynamic balance. A static balance involves putting a weight on the inside lip of the wheel only. This will prevent the wheel from hopping up and down, but on todays nimble suspensions this is not good enough.

A dynamic balance uses wheel weights on the inner and outer plane of the wheel and prevents the wheel from wobbling. The tire store kids avoid this because they get yelled at when they scratch alloy wheels with wheel weights. To dynamic balance WITHOUT scratching alloy wheels, a savvy wheel balancing tech will use tape weights just behind the spokes of the wheel for the balance of the outer plane.

If your tire store gives you a blank stare when you tell them that you want your wheels balanced this way, find another tire store.

As far as steering dampeners and other front end parts, I would not replace them until I got the vibration to go away. That way you have a system that will more easily tell you when a wheel is out of balance. Once the wheels are properly balanced then, of course, find and repair any loose or worn front end parts.

Good luck,

I agree with Larry. It could be poor balance. I got 4 new Goodyear tires recently, and the car shook as out-of-balance, yet the tires were spin-balanced on an electronic balancer. Found someone with a Hunter machine which measures road force (actually rolls the tire under load to check for uniform stiffness) and one new tire got junked.
My 420 was extremely sensitive to shake, to the point it was not drivable at speed, until I changed the steering damper; the old one offered no resistance when moved by hand. Everything fine now.

I would add that warped rotors will add to the harmony of vibration issues...

...though I have a number of front suspension parts that need attention, replacing the wheels,tires and all sorts of balancing did NOTHING to reduce the highway-speed vibration issues...until I finally replaced the original rotors on the car. Vibration reduced by about 95%!

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