99 E320 Suspension Vibration - PeachParts Mercedes-Benz Forum

winterbean · #1 07-21-2010, 07:31 PM

I can feel a front end vibration in my wagon between about 50-65 mph that suggests a tire balance issue. However, I've had the tires balanced at two different tire shops and the problem persisted. My usual local mechanic at MBI insists that the problem is tire related: balance or out of round. So, does anyone know of a suspension problem that would cause this? The car handles fine, and there are no alignment issues.

mbdoc · #2 07-22-2010, 08:17 AM

The front lower control arm bushing can cause that type of issue.

They are a hydraulic style of bushing, filled with oil.

winterbean · #3 07-22-2010, 06:50 PM

Thanks! That's what the 4th local opinion said, as well. They quoted the, absurd to me, price of $700...any reason why it would be so expensive? As I understand it, the bushings can be replaced without replacing the whole unit.

mbdoc · #4 07-23-2010, 08:11 AM

Yes, with correct tools that can be done ON the car.
And yes, MB offers JUST the front bushing. You do not have to buy a complete KIT.

winterbean · #5 07-23-2010, 01:22 PM

I considered removing the arms myself and taking them to a shop to have the new bushing installed, but the idea of doing them on the car is much more appealing. What special tools would I need for the on car installation? Any chance I could rent these?

winterbean · #6 07-23-2010, 06:46 PM

Found a shop that would do the bushings for a reasonable charge, except they refuse to do the work because, "the control arm bushings have nothing to do with the vibration you're experiencing."
It would be nice to be able to test the bushing to see if they're bad, but I don't really know any way to do this while they're on the car.

bbarcher · #7 07-26-2010, 01:23 AM

Worn tie rod end could allow enough back and forth play to develop a shimmy/vibration. Felt in the steering wheel, and could also cause a knock/clunk noise over bumps.

Bushings are generally pried on for excessive deflection and visually inspected for cracks. Somebody could mount a little video camera in there to monitor for play in various components if it is that hard to figure out. When I worked at Ford I saw some engineering videos from under-car cameras, and it was very surprising how much force was being applied to certain things during regular driving, and how much they moved under load. It is difficult to duplicate real driving loads in the shop.

At the least, I suggest having a non-tire shop indy diagnose it. Sounds like the shop that you just mentioned might be worth trying, as they have shown a lack of greed by refusing to work on something they don't think is the cause. Maybe they are willing to take a fresh look at it.

Certain tire faults can go undiagnosed, such as excessive road force variation. The tire may balance out fine and be round, but can still cause vibration. Usually excess RFV is more common on lower end tires, but it is always a possibility. Not all shops have a machine capable of testing for it. For more info on this tire issue, check out gsp9700.com. You can see if your local shops use this equipment. Often they will only use it when necessary or they may charge extra for it.

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