Sounds like caster to me, have you measured the angle? Every truck is different so comparing won’t help, you need the numbers with your setup. Simple to fix with wedges for SUA lifts, what you are feeling is the wheels falling into turned positive.
Measured the toe. Found it to be 5/16 inch toe in. Now off to find the spec.
my method: I set the front end on jack stands. Spun each tire and scribed a chalk line on the tire tread as it spun. Measured line to line on the front and back of the front tires with a helper holding one end.
That could make for nervous turn-in. Might be delayed because of slop in the system. I'd expect excess toe in + caster + potential components in system being due for rebuild/replace adding up to less than nice steering.
Another thing that would likely help out pending the state of the stock suspension would be springs/bushings/shocks (I'm happy with my OME springs and Bilstein 5100s). I second or third the idea that rearching is not what you want to do for 2-4" of lift.
Adjusted toe and my preliminary impression is that the condition is improved. I was only able to test on city streets and corners. I will need a rural road with varying radius turns to tell if its completely resolved.
I took a look at things while I was under there. The TREs are all newer. The center arm is newer. The bushings in the prings and shackles are not newer and look degraded. I need to learn a little more about springs and shocks. One would presume that the springs (OEM I think) have relaxed over 40 years. Do any of you have a spec and a method to determine how much they've relaxed. I may get the lift im looking for by simply returning to original arch geometry.
Since it's a related topic, could some of you comment on body roll. I plan to replace my shocks (currently original I think) with Bilsteins. Are shocks valved to limit slow roll but allow rapid bump articulation? I won't get to replace the shocks until I do the suspension so I know the correct length needed, but I want to be ahead of that game when I get there.
Preface regarding cornering on these things...they're not particularly good on sweepers even in a proper state, especially with hardtop and rack.
Shock-wise Bilstein 5100s are generally accepted as the best reasonable cost off the shelf option, search the forum for part numbers. I'm running the same shocks I was on stock springs with my 2" OME, I think they overlap (esp if you're not wheeling hard, which I actually do). They will absolutely help with body control while not negatively impacting overall ride.
Springs probably search forum too, should be able to measure from hub to fender to understand sag.
I had the same issue with my 76. I have a 4” with 33’s and stock steelies and mini-truck steering as well. I rebuilt my center link when I noticed a little slop and also rebuilt my drag-link end where the pitman arm goes in. I also tightened my steering box a little and put a set of 4degree caster shims. I noticed a big improvement after all this small stuff and now the steering almost corrects itself like it should now. I should’ve ordered the 6 degree shims
I can not believe what a different this small alignment adjustment made! Today I drove up to our local ski hill which is the same drive that got me fed up with the cornering behavior and sent me looking for answers. The weird progressive turn rate was resolved and as an added bonus, body roll was significantly reduced.
thanks to everyone who chimed in to help me out. When I get wheels, tires, lift, I’ll have the alignment checked and plan on adding shims.