truck bounches around at 40mph?

when i get going it drives like a dream but once i hit 40mph the truck wobbles pritty bad. and stel had a small shimmy at highway speeds. now do i need a tire ballance? and yes thers air in the tire. or i herd something about a kingpin? please help

I know that with my old Dodge when the Idler arm needed replaced it would do that at about 40 then go away. But after it got worse, it did it all the time. But I am guessing you are talking about a Ford. I am not sure how hot it is in AZ. right now but you might look for a buble in the tread of one of your tires. I have had that happen to where at slow speed you might not notice it. Just jack up one tire at a time about 1 inch off the ground then give it a spin. You should be able to spot it then if you watch the gap between the wheel and the ground. Other wise sometime they can be hard to spot untill
they are ready to blow. Next is to check for a bent rim that maybe got curbed or something like that.
Hope this helps. Kurt

i took it to discount tire and they did a tire check, no cracks,bubbles or dry rot and the rims are 2 months old fresh outa the box! and ther aint a idler arm its a 66

Any component in that front end could be your problem, or a combination of more than one of them. Start by jacking up the front end and grabbing the wheels and shaking them up and down and back and forth. You can also put the tires firmly against a curb so they don't move and then turn the steering wheel back and forth to see if something is loose or worn out.

I assume this is a straight axle front end? If so, you want to look at the kingpins for play, the tie rod ends, wheel bearing adjustment and condition. Have you had it on an alignment rack? Steering box could be worn or shocks could be bad also.

So many places to look, you just have to do process of elimination.

Don

its a twin I beam. and it was aligned a few weeks ago, the shocks at 44 years old lol and the steering box has alot of play in it also 44 years old

Early twin I-beam axles were notorious for wander/wobble. You hit on a couple of things already that can cause that problem, the sloppy steering box(biggest offender) and ancient (and probably useless) shocks. Also, another area is the 'rubber' pad/bushing where the two struts meet up at the frame. Occasionally the bolting or rivets that hold the bracket to the frame are worn as well. Also, this was a high rust area. Water and crud were trapped there. The bushings on the axle frame ends themselves could be shot. Then, of course, the king pins. Unfortunately the guy at the alignment shop, unless he is a REAL old timer, most likely doesn't have the experience to deal with the old Fords. Unless these shops have specialized equipment, all they can do is set the toe. Caster and camber require hydraulic axle bending tools to adjust - and very few shops ever had those tools nor the skills to bend the axle right.

Yep I just went thru the axle bending on my 70 Ford pick up last year.
And there ain't alot of folks around here doing that anymore.
Nate You really didn't say what you were working on in your first post
but I thought you might have been talking about your 66 Ford.
Thats why I said, But I am guessing you are talking about a Ford.
I was trying to cover the things I would look at first. Kurt

If the truck has never or even recently been maintained----all the rubber biscuits are dryrotted and have no cushion or dampening capability left--spending money on any alignment/axle bending/ect will just be wasted dollars and lead to more frustation because it won't fix the problem/problems.
As already stated, lift the wheels off the ground and shake in all directions/planes---the cross links/idler arms/etc on those series of trucks were lucky to last any amount of time!

If the king pins/bushings are bad they can be easily repaired . replace the steering links/tie rod ends and all the axle mounting bushings along with a good set of heavy duty shocks--then have aligned and you can be confident that the job will last.

44 year old rubber is so worn out it probably won't even smoke/smell when you burn it

well guys i rebuilt the front end and stel had the shimmy!!!!!! them i seen a ring of grease arounf my rear tire! pulled the shaft and the bearing was shot to hell!!!!! maby that will fix this?????