steering goes "woogie-woogie"

[psychopathicdude]

One of the vehicles I drive at work is an older (I'd guess late 80s or early 90s) Ford pickup-cab/flatbed truck with a turbodiesel V8... I will try to get the year/model, etc... but here is the issue. Two particular roads that I drive on a regular basis are riddled with cracks and dips caused by sinkage/expansion... The suspension seems to have decent damping on all of these (decent by moving-van standards, that is) unless the dip is off center, or only under one side. Then there is a violent shudder in the steering wheel, and the whole truck shakes (one time it actually shook the ashtray out of the dash and onto the floor), only ceasing if I slow way down. Has someone experienced something similar and know what I should have looked at?

My boss has had the truck "looked at" before, one garage said "yeah, those truck suspensions'll do that sometimes", another blamed a belt-separation in one of the front tires. With two new front tires, it still does it (though somewhat intermittently)

I have a hypothetical hunch to check out the power steering system.... but I'm asking if there is something in the suspension that might be causing this. It's not my usual vehicle, so it might be a while before I can check it out, but I'd like some input (from rather broad and general info, I know...my apologies)

[taillight]

I would start with shocks and suspension parts.

[hotrod_chevyz]

Im guessing the problem is where the center link meets the idler arm. Ive seen them do this many times, hit the right road surface and the car (or truck) will shake side to side in a violent manner for a short amount of time. Could be other things too, but thats where i would start. If you find that its in the steering, check the ball joints and all the bushings (or just have them replaced), cause when they wear out past a certain point they allow components in the steering system to move in ways its not suopposed to, causing failures.

[psychopathicdude]

I made some deliveries with it Friday... It did it again at the usual place, but then again on a smoother section at lower speed. I agree it may be worn ball joints, or perhaps a faulty steering damper... Allowing play which under the right circumstances causes an oscillation that is perpetuated by the vehicles forward motion. I've told my boss these theories, he's going to call some places next week.

[MagicRat]

Look in the Jeep Cherokee forum section here at AF. Search the term "death wobble" (I'm serious here) for a detailed explanation of the components that cause this phenomenon. Its common with those Jeeps, and many of the engineering concepts are similar/same with your Ford.

[psychopathicdude]

Will do, Mr. Rat... I appreciate your input.

p.s. I catch the whole "death wobble" part, I thought the truck was going to dramatically disassemble itself right there on the road at 35 mph! (serious, indeed...)