Originally Posted by Rancher Rob
I've have/had lots of solid axle vehicles, including an F350, and never had death wobble until my 2019 jeep wrangler rubicon had a 3.5" lift and large tires put on it.
I've done a lot of research, took it to 3 different shops, and talked to a lot of folks (most of whom don't know what they are talking about as 75% just say to get a steering stabilizer).
What I've learned:
Tire inflation may be a contributing factor.
A little more castor alignment would help but doesn't necessarily solve.
A steering stabilzer/damper/shock did mask the problem but shouldn't be required if everything else is right.
Loose steering components and worn bushings can cause it.
In the case of my jeep, after speaking with a high end company suspension design engineer, I believe it is the light weight steering system (pitman, drag link, tie-rod) that allows the harmonics to resonate given the right bump and situation. So I've purchased a heavy duty steersmarts steering linkage kit but have yet to install it so can't confirm it does solve it. For the price, it better.
A couple of months ago I was driving a rental 2019 Wrangler. I think it had about 15k miles on the odo, and during one 30 minute drive there were 2 times where I was driving 60mph, very slightly downhill, and hit a bridge expansion joint. The right front tire went into an out-of-control oscillation that felt like it was going to rip the steering wheel out of my hands. Both times I had to slow down to below 40mph and the shake just went away like it had never been there. It was super disturbing, and I was glad that my wife wasn't driving at the time (she doesn't do well with surprises).
I just figured it was "a Jeep Thing" that I wouldn't understand....