How EXACTLY did you determine that you have only 500 lbs of tongue weight? With a trailer weight near 8000 lbs and a real 500 lb tongue weight, I feel that too light of a tongue weight is the trailer sway smoking gun.
Do you happen to have a good picture of the EX and TT hitched up? I'm curious to see how each is sitting ready to roll.

 

This...................

 

Something that I find odd is that with a light tongue weight the front end shouldn't be squirrelly. An overly heavy tongue weight with inadequate weight distribution would lift the front enough to make it do strange things. Maybe something else is going on.

 

The tounge weight was measured on a scale at the trailer shop. The scale was one made to fit in the crank post of the trailer. We then measured the distance from the ground to the rear wheel well. When the trailer was hooked up again that distance was only 1/2 inch lower. Sorry I dont have a pic, but the truck and trailer was basically level. With what I plan with added 110 lbs of propane in filled tanks and redistribution of trailer contents of about 200lbs I will probably add another 300 lbs which should bring my tounge weight to about 800 lbs. That 200lbs was previously behind the trailer axel. The lesser weight on the axel, by moving gear,
is also of a concern. I will then weigh the tounge weight again after my suspension upgrades.

 

Good question and observation. Many EX's are known to wander and be "squirrely" The steering box was tightened and that helped. My mechanic said the front OEM shocks looked undersized (light) as well as the steering stabilizer. The upgrades should help that. I believe the EX, being a large heavy SUV and made to be a family vehicle is the reason the suspension was on the light side. Several, and a freind thats a Ford mechanic with years of experience, have said this. After all said and done I will experiment with the WDH. When hooked up, I crank the trailer up about ten turns and then use the pipe to bring the bars up on the sixth chain link. This was all set up where I purchased the trailer and previously was fine before the tire change. From what I have reaserched and different opinions, the tire chage can change the whole equation.

 

I'm skeptical about that. On my prior 1/2 ton truck I could switch between the P-metric and LT (load range D) tires and nothing in my setup changed. The only difference in ride was that the truck's rear end felt squishy going around corners. The LT tires had stiffer sidewalls.

 

A year ago I would agree with you and I still do with one exception. I just got rid of a set of load range E tires that were "squishy". The thing with those tires is that I don't see how any amount of suspension changes could adjust for their "squishy" feel. The were erratic going straight down the road. Getting rid of them and going back to a known tire fixed the problem.

 

I've had the squishy tire problem once too. Had the shop put two new Firestone Transforce AT 10ply tires on the back of my old 99f150. Had the old Steeltex AT 10ply in the front. From that day on, the truck always felt squirlly. It got a little better after a few thousand miles but it was still trying to steer from the back. Drove it that way for a couple years until I got my 2010

Got those same tires on my 2010, and they are rock solid.

It could just be the tires.....

 

So good advice here. Something to consider, the propane tanks only help with tongue weight when they are full. What happens to that extra weight when you use the propane??
Keep that weight number when considering TW but remember that changes as you consume the propane.

 

Just expanding on that a bit... if you're relying on the fullness of your propane tanks to achieve optimal tongue weight, you might want to re-think your entire towing strategy.

 

Very well said.

Expanding one step farther, not accounting for full tanks when you buy and set up your hitch is also a severe miscalculation.

In my case, if not for the battery and propane, I could easily get away with an 800lbs hitch. But with them, I'm over the mark.

 

Mentioning the bias ply tires triggered a memory to me. I remember when radials first came out that I thought they felt squirreley. There was a musheyer feeling from side to side. I can feel it when a semi comes beside me. When the semi is next to the trailer but still behind the truck, i can feel the truck turn into the semis lane and you have to gently correct or you'll wag ur tail. Cross winds will do the same thing. I have little to no play in the steering, tie rods and pitman arm are all tight. I'm going to be going after the rear suspension next.