Rising Fawn

I recently replaced the tires on my stock 88 model Comanche Chief.
The old tires were more than 20 years old, and were cracking at the belt line, and 2 of them had developed holes.

Anyway, I replaced the old Delta AT Sierradial P235/75R15 tires with a new set of Dextero DHT2 P235/75R15 steel belted radials, and had the front end aligned.
There was no obvious problems in the front Steering/Suspension system although the Tech did mention that I had a oil leak out of the right front trans-axle tube, and that I probably need new shocks on the front.
I've been aware of the oil leak for a long time, and make a point of keeping the oil level full.
I'm planning on replacing the seal for the right front axle..the difficult one near the central axle disconnect (CAD)...when I get the energy.

Anyway, when I drove out of the parking lot with the new tires and alignment, I could not believe how much better and smoother the tires rode, and how much they improved the steering.
I started home down a straight, smooth, newly repaved highway and thought how really nice it was to have the truck riding and handling like this......until I hit 54 MPH, and then the "sh** hit the fan".
Death Wobble" reared it's ugly head, and it was a bad spell until I could get the truck back down to 40 MPH.
If you've had this problem you know that using the brakes only makes the steering worse and harder to control.
I've taken to using the parking brake to slow the truck down to around 40 MPH.
That's the speed where "Wobble" magically disappears.

Death Wobble can occur anywhere from 54 MPH up to 70 MPH on my truck, and you never know when it's gonna happen.
A slight bump in the road and "away we go".

I just don't get it, I have been chasing this problem for a long, long time.
If I could get a grip on this, I would have a sweet ride.
As it is, I'm almost afraid to drive it over 50MPH, because it never gives any warning.

This truck is not a daily driver, and actually gets driven very little, and most of that is highway use.
I do use it in the winter to haul firewood when I cut wood.
I've owned the truck for 22 years, and it only has 136K miles, most of which (88K) were on it when I bought it.
Could new shocks be adding to this problem?
It seems like Harmonic Distortion is causing the "wobble" to begin, and it gets worse progressively until it hits full tilt boogie, and then the front end feels like it may fall out of the truck.
If you have this problem, you will understand.

Any advice on where I can go from here.

thanks

Waynerd

I'm beginning to think the ball joints and control arm bushings are the biggest factors. My wife's '01 is beginning to get death wobble. It's got just over 205k I replaced the tie rod and drag link and track bar a while back just because I had the $ and they were originals. Only thing wrong was the boots were gone on all the rod ends. I can tell from the tire wear that I need ball joints. And now I'm thinking it might need control arm bushings since it's starting the death wobble.
Also my 98 has it only not as bad. It too needs ball joints. Also I replaced some of the control arm bushings and it's gotten better.

moparado

Nice Comanch!

Just about anything loose, worn or broke in the the front end can cause DW.
Usual suspects are track bar, tie rod joints, control arms, ball joints, pitman arm, steering gear box, incorrect tire balance can start a worn part to start the DW, etc.
Just gonna have to get under it and inspect all front end parts one by one.

On my XJ, while not a true DW only extreme steering wheel vibes at 54 to 57 mph was caused by worn lower control arm bushings, worn tie rod end and a worn steering gear box.
Smooth as silk at all speeds now.

This is a topic that has been discussed a lot here, you might want to do a search here for more info.