I have an '86 F-250 Supercab which I've converted to a Dana 60 front (from an '87 F-350). Truck is lifted 4" with lift springs in front, shackle flip in rear. Extended shocks, Rancho in rear, Superlift in front. ProComp drop pitman arm. Tuff Country drop bracket for track bar. Before installation the axle was completely serviced. King pins all completely replaced, including pins, bushing, spring, seals, bearing/race, etc. Re-used my wheel bearings, rotors, and calipers from my Dana 50 as they were all in good condition. Also, drag link is new. Tie rod is old, but ends are tight. Running 38.5"x15" bias ply tires.

So I did the axle swap weekend before last. At 20-25 MPH it would get set off into instant and extreme death wobble should you hit a bump the wrong way. Figured I needed a track bar, and these trucks aren't like every other leaf sprung truck out there due to flimsy shackles in front.

Fast forward to today. Get track bar drop bracket in mail and install. Test drive and initially I'm pleasantly surprised. Around town and even up to 30-35 MPH no death wobble even going over some stretches that were very bumpy and have set it into extreme death wobble before. So I work up the nerve to try a faster road. It takes a pretty bumpy stretch fine at 35-40 but when I accelerated beyond that I felt it kind of want to wobble even over fairly smooth road. Went back to normal, so keep driving.

Over a few light bumps around 45 MPH it got into a death wobble and had to drop speed to around 10 MPH before it would stop. This wasn't nearly as instant or extreme as without the track bar though. I could feel it coming on, and the oscillations getting worse. At it's peak it was not nearly as bad as before the track bar. There was pucker factor, but not, "oh crap I'm gonna die" factor. From when I felt it starting I had time to slow a bit before it set on fully. Also the oscillations or "tugs" at the wheel were distinctively slower and more controllable than without the track bar.

The plan is to get an alignment and have my tires rebalanced. Also gonna see if I can find some polyurethane bushings for the track bar. The bushings look good and seem tight, but maybe a better bushing will help. I've also read that shimming the king pin spring 1/8" to 1/4" can help. It was not clear if this was done to new or old springs though (mine are new). Also considering a steering stabilizer. I would prefer to fix the problem rather than mask it with shocks though. At least fix it before I do a stabilizer.

What else could be causing the death wobble? Anything else to try?

 

You are on the right track with the trac bar, but you have to make sure it is terribly tight, and you will have to make sure that the angles are correct.
Next is the steering design. Did you keep the inverted "y" style steering? This combined with the poor angle of the trac bar could very well be a problem. Inverted "t" will give you far less problems.
The solution with your SAS is to eliminate the fornt swing shackle and go right for the shackle reverse kit. This is a simple and effective solution to the problems that you have.
Glad you are willing to lokk further into this problem before you run out and stick some stabilizers on there. You can have a decent steering truck without the wobbles. JUst have to find the correct combo.
Have you any idea where the caster sits now?

 

2 important things Cory. did you put F350 steering components in with the D60, or did you reuse the 250 ifs stuff??

and when you put the pitman arm on, did you torque it down??
when i got the "death wobble" on my 88, a loose pitman arm caused it, and it then cracked the sector shaft of the steering box..
a new steering box, and new pitman arm got rid of almost all of the wobble except for on very rough roads, and dual steering stabalizer eliminated the problem for good.

as far as the poly bushings go, i did that route also. and 6 years later, i took what was left of them out and put the good old ford rubber bushings back in.
that was 13 years ago, and the rubber bushings are still like new.

the energy suspension poly bushings were the single biggest waste of money i have ever spent. after 3 years they already showed noticeable cracking, and by 6 years they were almost completely missing.

 

If you shim those king pins, you should remove the tie rod end from the steering knuckle so you can check for a bind after adding the shims. Just throwing shims in you could shim it into a bind causing more problems.
Like Ed says, get a shackle reversal done. Thats probably a lot of your troubles.

 

For steering I am using F-350 components. That goofy, flimsy, flexy setup on from the Dana 50 TTB looked downright scary. The setup I'm using is like, almost a crossover. Tie rod from one knuckle to the other. Tierod has a tepered hole for a TRE right next to the TRE for the passenger side knuckle. Drag link from pitman arm to the tie rod, attaches in the hole right next to the passenger knuckle. The drag link is new (including both TRE's on it), while the tie rod (between the knuckles) is old, but has no slop.

Would there be any advantage as far as death wobble to going with a high steer setup? It would probably allow me to get my drag link completely horizontal. Then I'd have to get my track bar completely horizontal as well though to prevent bumpsteer.

When I did the lift way back when, I did torque the pitman arm to spec. Not a pipe wrench job, I used proper tools.

Shimming king pins I'd obviously have to measure how much free space the spring takes up in the cap, as well as how far compressed the spring will go before binding, Then shim less than that difference. At that point maybe eliminating the upper spring altogether with an adjustable or shiummable high steer arm would be better?

As for shackle reversal... This may be ideal as it would get rid of the flexy front shackles and the tendency of front mounted shackles to encourage axle wandering. I see kits for 92-97 F-350. Will these work for my truck ('86 Supercab). I think those kits are for trucks with crumble zones. Also, my truck is already at the lift height I want. I hear the kits add 4"-6" of lift. I want to stay at my current lift. I still have my stock F-250 springs. Would I be better ditching the lift springs and doing a shackle reversal with my stockers? Or getting F-350 springs if necessary (F-350 is 1"-2" more arch in springs).

 

the only difference on my front end is that instead of using the crappy "A" shackles that go into the frame, i have "H" shackles that go outside the frame. and 4 inch lift trailmaster springs.

and i used stock F350 steering components.


the dual steering stabalizers is what fixed my truck.

 

What shackles did you use to convert from the A shackle to the standard shackle? What did you use for a bushing? What was the procedure to convert? I think I'd like to convert if not to a rear mounted shackle then at least to a standard H type shackle.

Also, when I ordered the track bar bushings last night I also ordered a dual shock steering stabilizer. Looks like it just has a U bolt over the frame to hold the bracket for teh shocks. How did you mount yours? I'm thinking something a little more solid than a single U bolt would be nice. I'd like to fix the root cause if possible before installing the stabilizer though.

Also, what should alignment specs be for a truck like mine (4" lift, 38.5x15 tires)? Should the specs differ at all from a stock F-350?

 

nope. set specs for stock. i set my front end for 1/16 toe in, and got 65,000 miles out of a set of BFG AT tires. they were still good tread, but got so dry-rot that the sidewalls started to blister and i was afraid of a blow out.
when i went to put the MT's on it, the driver side tire blew out as i pulled it into the shop.

 

Apparently my new track bar bracket was wiggling around just a small amount as the bolts holding it on loosened up some. Replaced one that wouldn't tighten back up, locktite, and hope for the best. Didn't feel like test driving. It's freakin' cold out, not to mention dark and the garage is currently occupied.

Maybe tomorrow if I can cut out of work while it's still light out I'll replace the three 12mm bolts with 1/2" bolts. Thinking the 1/2" will take up the small clearance in the bolt holes on the frame for a tighter fit to help prevent it working loose. We're knockin' on 0* with wind chill right now, tomorrow a high of 15* or so when the sun's shining so if I can get it done then, so much the better. Just no desire to be outside at the moment.

 

If the shocks are for a TTB truck, double them up or go to a stiffer shock. With the straight axle, there is a lot more weight to be controlled by the springs and shocks. Thi9s cured a horrible death wobble on my 84 F250, no track bar.

 

i think the proper bolt for the track bar bracket is 5/8. but it has been a LONG time since i did it. i do remember i had a hard time finding bolts that fit though.
and i used nylocks to prevent them from loosening up.

i agree on the cold thing. the 88 is sitting along side the house with a bad starter.
there ain't no way i am getting under that beast to replace a starter when it is below freezing out there.

 

Put 1/2" bolts in for the track bar drop bracket. They were a might better fit than the factory 12mm bolts. Cranked them nice and tight with nylocks and locktite. No death wobble last night when I had the truck up to about 55-60 MPH.

It wanders a lot though, following grooves/ruts in the road. It's certainly a handful to drive on the highway if the road isn't flat and smooth. I'm still not 100% sure death wobble is gone. I'm nervous to go faster. I'm going to adjust my steering box as I think I'm getting a little play from that. Hopefully the steering stabilizer will reduce the wandering.

 

well, that is definitely a start.
good luck, and keep warm.
how is it down there along the Delaware river??
it is colder than a $%^%@*& here on the shores of the Raritan Bay!!

 

Yeah it's pretty cold out. Warming up a little for today and tomorrow though. I pulled the track bar off and burned the old bushings ou only to find tehre's a pressed in sleeve in each end. Just got one out after a long time with heat and an air chisel. Gonna tackle the other then finish cleaning up the bar and paint. While it's drying I'll do some needed work to my bike, then pop the new poly bushings in and throw it in the truck. Tomorrow hopefully I can get the steering stabilizer on.

Interestingly enough I was over my buddies house last Friday and he has two F-350's a couple years newer than mine. One (reg cab '88, stock height with 33" tires) has no death wobble and no stabilizer. The other is a reg cab utility body dually (his work truck) 4x4 and he has a dual stabilizer on front. Said it shimmied and death wobble like mad on the highway until he put that on, even though all the steering and king pins were tight. Strange thing is that truck is done stock as it came from the factory.

Not sure what it means but I'm hoping when I get hte steering stabilizer on mine it'll be comfortable on teh highway. As it is the truck wanders and follows ruts like mad at highway speed, and I've had a couple times it feels like it's starting to death wobble but it hasn't gone into an all out wobble where I gotta hit the brakes and slow way down. Once was actually on an extremely bumpy broken down road at maybe 20 MPH though. I'd prefer to fix it without the stabilizer but I don't know. I'll see how it feels to work and back tomorrow with the poly track bar bushings before I put the stabilizer on tomorrow night.

This truck needs to have no death wobble issues at all by summer because I pull my boat with it and pull the boat if I gotta worry about death wobble.

 

just a thought. how are the bushings in the spring shackles in the frame??
if those little buggers are bad, that will throw the front end all to hell.

not the bushings in the springs, but the bushings in the shackles themselves where the shackle goes up into the frame and the bolt goes through it..