Hey all. I'm an idiot, and I bought a 1989 F-Super Duty wrecker a few weeks ago that I don't have room for. I saw it and I had to have it.

But it's not just any wrecker. It's a rust bucket that has had the drive train from a 4x4 F350 swapped in. It has an EFI 460 and ZF5 Trans. I got the engine running well after playing with the timing. I got the trans shifting OK-ish after changing the oil. I got the brakes working after replacing 90% of the brake lines.

Right now my big issue is death wobble at 45-ish mph. It's violent. Much more violent than Jeeps and SAS'd Toyotas that I have had in the past. The front end is very tight. King pins feel tight when trying to rock the tire by hand or using a large pry bar. I don't know is what this front suspension is comprised of. I have a few thoughts:

-This track bar is sketch. The truck has what appears to be a 4" drop pitman arm, I assume a new track bar and matching 4" drop bracket is in order?
-The tires are counter balanced on the inside with no weights on the outside.
-I need to check alignment. I guess I would just shoot for like 1/8" of toe in?

Can any one ID these front springs? I not having any luck looking up the numbers. I don't know if they are stock Super Duty springs or F350 springs. I'd like to do a RSK, but I don't think I want any more height, as I don't think the wheel lift would reach the ground.

Any other ideas? I assume king pins will move like ball joints when they are worn? This is my first king pin front axle.

Thanks!

 

I would start with the steering gear. Loosen the lock nut on top of the gear. Turn the adjuster inward while holding the lock nut as someone is gently rocking the steering wheel back and forth. Sometimes, it will take several turns to get the slack out. Stop when you feel roughness or tightening of the adjuster. Lock the nut. Hopefully, the gear isn't worn out.

 

the home made track bar is your problem. it should be on the same angle as the steering link from pitman arm to tie rod.
once that is straightened out, than add a steering stabilizer and the death wobble should disappear.
tightening the steering box is not a bad idea, but not as important as the other two items.

 

Looking at the photos, I am surprised it sits so high in the front seeing as how its an OE installation. The springs appear to be the same 2-leaf ones i have in my SAS truck, which i am told were stockers from a late bullnose F350. I did a RSK, which is supposed to lift 2-2.5" and it appears to be close in height. I cant see the rear spring bracket well, which are the only other thing that can add lift if custom made, but they appear to be OE units. All that said, I would start by replacing that track bar. There are companies (sky is one of them) that make adjustable bars that compensate for lift. With my RSK, I had an issue with my bar interfering with the bracket at the axle end, so i clearanced it. It appears someone added a bend to yours to solve the same problem. There's so issue with the bend as it will act as though its a straight bar (there is no other geometry going on here so a straight line can be drawn from one pivot to the other). Its likely the bushings are shot, allowing the axle to move side to side, amplifying the wobble. Toss a new bar on there along with a new steering stabilizer and see where that puts you. It appears the drag link bracket for the stabilizer is rotated down quite a bit. The stabilizer should be in the same plane, behind the drag link. Seeing as how you checked the kingpins, its tire balance and alignment after that. Potentially worn leaf spring bushings?

My RSK without modifying the rear spring mounts, creating approx 2.5" lift up front.

 

the F-SuperDuty had a drop axle in front. that is why the front is as high as it is, the D-60 will make it sit 3-4 inches higher than a stock 2 wheel drive F-SuperDuty.
i bet the rear end has around a 6 inch block between the axle and spring too.

 

It has a 3-4" factory style block, but a gigantic leaf pack. Thanks for the info!

 

Thanks advice! Early this morning I ordered the Sky 4" drop bracket to match the pitman arm and their adjustable track bar. Bushings looked good, but I'll take a closer look when it dries up today. The track bar that's on it has really scabby welds from where it looks like it was extended, so it was a priority to replace it. I'll adjust that steering stabilizer and replace it. The body on the stabilizer is pretty oily, so I'm sure it's shot.

 

FYI , that track bar was sketchy. New adjustable trackbar and drop bracket are in and there's no more death wobble, even with unbalanced and super flat spotted mud tires.

 

Thanks for the feedback and good news your issue is resolved.