wandering front

Hank, sounds like a typical case of front end alignment issues. I didn't see the article or even own the same rig you have but my 08 F550 was doing the same thing and I had the caster set to about -1 degree ( I think that is correct) and it took the light or over steer out of the rig. It drives straight down the road now without having to over correct constantly. I have also setup several off road Jeeps with big axles, big tires and complicated suspension geometry and if the caster is set too far positive the Jeep will wander all over the road. It is called over steer and is a symptom of incorrect caster. Consequently if the caster is too far negative it is very difficult to steer and make corrections, this is under steer. Hope this helps you out.

Are you towing a trailer or car on a dolly?
Have front end alignment checked?
Steering damper?

Hank, What are your:
Axle Weights
Tire Pressures
Coach Length and Wheelbase
Aspect Model Number
Alignment Numbers esp. Caster and Toe
And:
Any chassis/steering upgrades so far?
Are you towing a Vehicle or Trailer?

Alignment-Wise: On the E-Series, Road Wander is a result of too little Caster and not too much. Mid-range spec for E is around +3 and we're finding +5 tracks much better. The F-Series must be different because if an E went less than +3 let alone negative you'd have to tow it or park it.

j-d wrote:
Hank, What are your:
Axle Weights
Tire Pressures
Coach Length and Wheelbase
Aspect Model Number
Alignment Numbers esp. Caster and Toe
And:
Any chassis/steering upgrades so far?
Are you towing a Vehicle or Trailer?

Alignment-Wise: On the E-Series, Road Wander is a result of too little Caster and not too much. Mid-range spec for E is around +3 and we're finding +5 tracks much better. The F-Series must be different because if an E went less than +3 let alone negative you'd have to tow it or park it.

j-d, +5 degrees sounds crazy to me. They must really have those Fords loaded heavy over the front axle to cause you to put that much caster in one.

Yeah, I know. Call it counterintuitive, but... An OP here called Harvard tore this issue apart trying to get his E450 to track AFTER he paid a shop to align it. What he finally did was crank his adjustable offset upper balljoint bushings up by 2* Caster over where the shop left it. Went from around 3* to +5.0*L and +5.3*R and got it to track like a passenger vehicle. Everybody who's gone with his suggestions has reported vastly improved tracking.
But I have personally been to The Mountain. Visited the Mecca of RV suspension tuning. Hendersons' Line-Up in Grants Pass OR a couple weeks ago. I mentioned Harvard's 5* caster and John said "Sure. I worked in the shop 25 years and did lots of alignments. That's what we do." That settles the debate far as I'm concerned. John also didn't see Class C tracking as the major issue we hear about here. Said a Rear Track Bar and Safe-T-Plus steering stabilizer usually gets them driving well. That's another point of note about Henderson. They've chosen the best components for each item. They're big on Roadmaster for sway bars and other items. But they go Safe-T-Plus for stabilizers, not Roadmaster's Reflex competitor. Henderson owns SuperSteer, so those components, like Track Bars and bellcranks for Class A are their own products.
I'm told that too much Caster will make one shimmy, but I'm not convinced an E-Series, which is what we're discussing here, can be set high enough to reach that point with the alignment kits that are available. Hank is on track trying to use some rear suspension lift to shift weight to the front axle but there's only so much that an inch of lift will do.
I'm asking what the Aspect Model is so I can look at both Length/Wheelbase AND Floor Plan. I'm forming the opinion that handling problems originate from the Floor Plan. What? Lemme 'splain: Marketing tells Styling that a Walk Around Rear Queen layout, perhaps with a Slide back there, is what sells. So don't just do that on the 31-footers. Put it on the 27's and 29's too. What's ahead of the bedroom? Bath and Kitchen. The Fridge and the Shower offer a place for the wheel well bulges, so Styling tells Chassis what the Wheelbase should be. Shorter coaches get the same "rear clip" as longer ones and it can impact axle loading which has a relationship to tracking.

Very nice detailed explanation.

Thanks. We're making progress in understanding handling/tracking issues. In some ways, just catching up what the professionals haven't told us. Henderson didn't hide secrets, more like nobody asked.
I know F-Series drives differently than E-Series, and for the better. A friend had an F-250 short box towing a Fiver and then an F-350 long box carrying a heavy BigFoot slide-in. I got to drive both over long distances. Both were SRW V10 Extra (not Crew) cab. Both tracked better than a Class C.
Usually we can help Class C owners with Ford chassis get improvement. Then there are some who testify they didn't have to do anything to drive OK. Waiting on Hank's info, especially weights.

The alignment shop I went to a few years ago set the caster to +5.2 deg L and +5.7 deg R. This is not any run-of-the-mill alignment shop, this is the shop other alignment shops send their work to when they can't figure it out. They are well aware from their experience of the Ford E350/450 tendency to wander.

Take the caster talk to heart. Also set your front tire pressure using the tire weight chart. Mine is far more skittish and likely to wander when the front tires are set at 65 PSI, vs. the correct weight setting of 45-50 PSI on my light class C. After being weighed I was surprised how low the front tires needed to be set.

I found the Roadmaster sway bars to be beneficial in firming up the handling. It feels more tightly connected to the road. I haven't changed the stock shocks but I suspect well chosen aftermarket shocks would also help tighten up the handling. In addition to the wander, I didn't like the general sloppiness of the handling dynamics.