having bad death wobble in my '85 pickup.
from what I've read so far, sounds like any or multiple of the following could cause this:

improper alignment
loose shackles
worn wheel bearings
play in steering joints
tires out of balance
anything else?

before i start throwing money at this... does anyone have any suggestions for which reason(s) are most likely to be the cause?
truck drives well at all speeds with no noticeable shake or anything. but, if i hit the right kind of bump at the right angle, it starts shaking bad and won't stop until i come almost to a stop. happened on the highway twice yesterday at 65mph in traffic with no shoulder to pull onto. not good.

i had the same problem with a dodge 2500 and it was the track bar.

i've looked under the truck and i can't find any play in any joints or wheels.

 

I would start with the cheapest thing to replace first, so check the spring and shackle bushing, then make sure everything is super tight. from there pull knuckles apart check that the housing is not bent, and double check the preload on the wheel bearings. After that it may be turion bearing or tierod ends. Your tires may need to to be rotated or inspected at a tire shop.

Over all check and recheck everything you can, and I bet you will narrow down the issue or issues. Good luck

by the way, I am doing a death wobble inspection on my own rig today as well.

 

Steering stabilizer? Shocks? Bad trunnion bearings? These may be some things to check.

 

Inspected with the vehicle on jack stands? You get better results

 

ok so I finally had a chance to jack it up and have a more thorough look.
what I found is that all the steering joints seem good and tight when checked individually but there still seems to be a good amount of play overall.

pretty sure my steering stabilizer is shot, but that alone would not be enough to allow such violent shaking would it?

also, the play is only felt when wheels are straight. when pushed/pulled toward either direction, then everything seems tight again. does that make any sense?

There is definitely some play in the wheels too. Is there a way to distinguish between problem wheel bearings vs trunnion bearings?

shackles are as tight as can be without using a cheater bar or impact wrench...

thanks

 

Grab tires at 6-12 o'clock and tug, repeat at 3-9 o'clock. If same play at both locations, wheel bearings, if worse at 6-12, then knuckle bearings. For overall steering play, follow the linkage back while moving the tires back and forth. At some point, you see one linkage p[art moving and the part it is attached to not moving. The point where the motion stops is where the play is located.

 

make sure your steering box is tight. I had a really bad death wobble exactly like you are describing, ended up being my steering box mount was broken and the whole steering box would move back and forth. also make sure your bushings in your springs are good