Well......

Now I'm thinking it may be the trailer.

I had a new axle put on the trailer the same day I did the ball joints. We tore the truck down today and couldn't find ANYTHING wrong with the installation. After putting it back together, we took a close look at the trailer.

The axles are uneven by 9/16th of an inch. When you hitch it up, that shrinks to 1/4 inch - due to the way torsion axles flex I'd assume.

We took it to the shop and inquired about this. The guy said that he usually shoots for 1/16th difference - but was obviously off a little this time. He said that the front axle is worn - the rubber in it has aged. He showed me where the right wheel angles up, and the left wheel angles down. The new rear axle is fine. He advised me that since I have a new and old axle, I'm getting sway. We hooked up to one of their new 18 X 8s, and I pulled it with no issues.

I don't want to spend another $645 on an axle, but will if I knew for sure that would solve my problem.

I'm really disappointed in the truck though. I asked a Ford mechanic today why my neighbor's Chevy and his half ton pulled my trailer just fine. He told me that the frame of the 2wd truck isn't as tough and cannot mask small sway issues.

 

2WD or 4x4 on SD has nothing to do with trailer sway. I know a lot of folks with 2wd SD's that pull all kinds of trailers with no problems at all. I would attempt to pull a couple of other different trailers about the same size as yours if you can just to confirm the truck is good. It sounds to me like the problem is in the trailer unless you do get sway or darting whether you have a load behind the truck or not. That would confirm whether it's the trailer or the truck for sure. I do think the truck is ok, though.

 

If you hooked up to another trailer and the problem went away it must be the trailer. I would go to another trailer outfit and pick their brain a little bit. That was a bittersweet experience with your ball joints.

 

Do 4WD SDs not have a tougher frame?

I just found it very strange that an 03 Chevy 3/4 ton 4X4 and a newer FX4 half ton with 50 series tires towed the trailer with no issue.

Could it have anything to to w/ my rear shocks? I upgraded the fronts to Blisteins a few years ago, but didn't touch the rears. I've got 87K on the clock and would assume that they'd need replacement, but they passed the bounce test.

 

Shocks would not make much difference on sway. That kind of sounds like a tire issue with the SD. A 2wd has just as strong of a frame as the 4x4's have in a SD. Like I said, I know a lot of guys that tow with 2wd SD's without a problem.

 

Palsey???

Try it with 2 hands on the wheel compared to one hand. your hands can fight each other unbeknown to you.
sidewall flex causes it make sure your tires are inflated to the manufacturer's recommended cold temp max usually 40 on a car tire and 60 on an LT tire.
check your toe setting it should be about an 1/8th in at the front compression brings it to near zero at road speeds. toe out makes a vehicle want to jump left or right whichever tire has greater traction. Make sure your not running those big fat sticking out mexican low profile slotcar wheels or it will do everything but try to go straight those are all looks and negative performance. there is something called the balljoint inclination angle. it is a line drawn through upper and lower balljoints and the closer the tire's contact patch is to where that line intersects the pavement the more neutral the steering will be. monster trucks keep in line with the inclination angle because the tall tires raise the axle by the same proporion the track widens keeping the inclination angle in line with the tire's contact patch

 

If you put bilstiens on the front and you left the stock ones on the back I would think it makes a big difference, the bilstiens are 3 times harder to compress than stock, and the rear of the truck will drop first on a bump especially with tounge weight on the back.

 

Don't forget shocks have ratings for push and pull resistance and they can vary in both directions a lot.

 

Why would you have to replace the whole axle just to replace worn rubber?

drop your springs, and replace the bushings...

Are there any differences in the trucks? Is the distance from rear axle to hitch point the same on all of them? Are they all the same cab type?

And finally when you're talking about sway, is it a constant sway, or is a forceful wobble?

 

The Moog ball joints are ok, the trouble is that you have to torque them in order, according the the instructions in the box. I install spicer parts and they are not as sensative to preload. We do grease them by hand under the boot and through the fitting on install. I have replaced many new moog ball joints to resolve this issue. I have not had any issues with durablility or wandering on the spicer product.

When we align supedutys we start at the factory spec. and go from there. Most e/f250-550's have to be driven and tweeked. That is the nature of the beast.