There is one other thing that I did not think of until last night. If there is a panhard rod in the rear end, its bushings and mounts should be inspected. It could cause this problem you are having and it is so easily overlooked.
ok4450 and CapriRacer: Yes, I admit that the ball joints may be causing the problems, but convincing my mechanic to replace joints that “test perfectly” might be impossible. At one point I had found an internet page that showed the construction of Dodge ball joints, they have a fair amount of plastic in them which may have crushed a bit over the years. I may not be remembering that fact correctly.
Keith: I don’t think it has a panhard rod, I could not see one and the factory repair manual does not list one in the index.
No matter what the computer says about being within spec, you ALWAYS have to favor the left side with at least 1/4 deg. less caster or the vehicle will ALWAYS pull on rodd crown. Specs are mostly BS when it comes to thisbut experience is what I’m talking from. favor the left with between 1/4 and 1/2 deg less caster and you’re good.
It is fixed! The ball joints finally started knocking (73,000 miles) and easily failed Dodge’s ball joint test procedure. It still does not steer like a new car, but it is infinitely better. The alignment shop thinks there is some slop in the steering gear, but I can live with that at present.
Thanks for updating us! Always good to know of a resolution.
I had a front ball joint go dry on my '88 Accord.
It started as a subtle bit of torque steer, built up very gradually, a few 1000’s of miles before I was certain something was changing (in the middle of a 3800 mile road trip).
Luckily it held up for the trip; started squeaking a little the day before we got home.
BTW, after returning I had all 6 ball joints, front and back, replaced on that 13 y.o. car.
Panhard rod, don’t know what I was thinking, trucks have leaf springs. Do this test, have someone follow you, or have someone drive your truck and you follow it in another vehicle and see if it is tracking straight down the road or if it is “crabbing” AKA, dog-legging down the road. That is where the truck is pointed off center of the direction it is traveling in, like a plane coming in for a landing in a crosswind.
If it is doing that, the problem is in the rear, not the front. With leaf springs, that can be one of the bushings in the leaf spring mounts or even one spring mounted backwards, but that would be really severe.
A 4 wheel alignment check should also uncover this but normally you don’t do a 4 wheel alignment when the rear is not adjustable.
Modern ball joints use UHD (ultra high density) polyethylene as a lubricant instead of grease. It does not compress very much. What can happen is either the material used in the ball was not hard enough and the ball wore down or the ball was not machined smooth enough which will wear down the poly insert faster. Made correctly, these will usually last the life of a vehicle. Some that were sourced from China when they first started manufacturing them were not made right.