This months Trailer Life makes the bold statement that the IRS rear suspension on the 2003 Expedition make the vehicle a lot more stable than the previous Expedition because it stops the movement of the rear sideways.
Does any of our engineering types on this thread believe this or is this new towing technology.
I know Trailer Life makes some misleading statements sometimes but this article seems credible to me.



fknipfer

 

It is easier to lock an IRS in place to prevent side to side movement, because you only have to locate each wheel assy, not the whole axle. The other big advantage is better ride and lower unsprung weight.

The downside of IRS is that the ground clearance changes with load and the camber also changes with load. An overloaded IRS will eat the tires.

Ultimately there is a reason that virtually all sports cars and luxury sedans have IRS and virtually all trucks don't.

On the Expy, the short wheelbase, P rated tires and low GVWR really limit the size of the trailer you can tow more than the GCWR. I use a Hensley Arrrow to eliminate sway on my truck.

Ian

 

fknipfer,

Trailer Boats as well as Power Boat Mag. have done towing tests with the new Expy in the last 2-4 issues and gave it great marks. They didn't skimp on boat either. TBM used the same boat I've got and PBM used something like a 27' Power Quest (I think).