Bad wander

bob_nestor wrote:
I had two 2004 E350 RVs. One drove like a video game - absolutely no road feel at all and if I didn't stay on top of it constantly it would wander all over. The second drove like a car - good road feel, no wandering and tracked straight as an arrow. Now the difference could have been alignment or caster as others have pointed out, but both were aligned by the same shop presumably to the same specs. I talked to a Ford engineer about the problem once, and he told me it was a simple firmware adjustment in the fly-by-wire system that just required a tweak to add more feedback into the system. He told me any Ford dealer could have preformed that adjustment.

Say whaaaaat??
It was probably just low on blinker fluid on one side or the other..

Given the F450 of that year that we should be discussing info about 19.5s with stock Gs and a pronounced shoulder ... not Es or less.

I will for sure check it out

I had two 2004 E350 RVs. One drove like a video game - absolutely no road feel at all and if I didn't stay on top of it constantly it would wander all over. The second drove like a car - good road feel, no wandering and tracked straight as an arrow. Now the difference could have been alignment or caster as others have pointed out, but both were aligned by the same shop presumably to the same specs. I talked to a Ford engineer about the problem once, and he told me it was a simple firmware adjustment in the fly-by-wire system that just required a tweak to add more feedback into the system. He told me any Ford dealer could have preformed that adjustment.

The wheel ruts are not that great. Its where the pavement meets. Middle of the highway and the shoulder

Another possibility could be the wheel ruts in the highway caused by heavy truck traffic. If it does it on any and all roads then it must be something on the truck. I ran into this once.

From Popular Mechanics May 1973

QUOTE:
"If too little caster exists, the car will wander and weave, thus necessitating constant corrections in steering."

And for a heavier tire, the more caster needed. This is why off-roaders have the problem when they go to a larger tire and set the caster to factory specs after the lift.

I would insist that the dealership recheck the alignment and set the caster to maximum side of the specs allowed. IF that dealer doesn't work on a lot of large truck (i.e. only works mostly pickups and cars), find a dealer that has more experience with F450 and up trucks. Remember, the warranty is provided by manufacturer, not the dealership.

Also, as Old-Biscuit suggested, weigh the truck. Then you can check with the tire load chart and ensure you are running the proper pressure for the load.

I think it must be the tires as my F350 with Lance 1161, what is very close set up - drives like Cadillac and most of the time it is 2 fingers control.
I have 62 psi front, 75 rear on 17" tires

19.5s do feel different than other tires. I can't say if you are feeling something strange or normal. I'm assuming they are tracking when there is a distinct indentation in the road. If so, that is just something to get used to.

80 is probably the pressure to have at max GVWR. The will get better with more wear. Some 19.5s are worse than others. NOTE: I've been running 19.5s for around 11 years with 4 different brands.

Oh, and the low profile tires on my Mustang track as well, so it's not just a 19.5 thing.

From Popular Mechanics May 1973

QUOTE:
"If too little caster exists, the car will wander and weave, thus necessitating constant corrections in steering."