Class C Stability Assist

[TexasJoePro]

Looking for some first-hand experience/technical advice on improving drivability on my new motor home.  We have a brand new, 2018 Thor Four Winds 24F, Class C motor home (25 foot length) on a 2017 Ford e350 chassis that still has paper tags!  (I just sold an older 38' diesel pusher and purchased this unit new within the past month.) The old DP had me spoiled on how it handled on the interstate - no 18 wheeler push-pull when they blow past and very little wind issues of any kind. Now I fully understand the e350 chassis will never match the DP with its air ride and massive weight differential and spartan chassis, but I would like to see what steps I can take to improve the ride stability, drivability and driver effort requirement on the e350 with a shorter rv. I've put about 1500 or so miles on the new unit and the 18 wheeler blow-by is rather intense! I have done some research (googling and in other groups) and here's what I've come up with:

1. Check 4-corner weight and rebalance after loading up

2. Get a "road loaded" front end alignment after rebalancing

3. Consider installing aftermarket front and rear sway bars.

Anyone have any experience with any/some/all of the above or have other suggestions? I think the first two items - rebalancing and re-aligning make sense, but I'm not very familiar with sway bars. Any input/advice is greatly appreciated. Thanks!

TJP

 

[SWharton]

We have a Class A and found the rear track bar solved the truck blow by problem.

[TexasJoePro]

SWarton - Is a track bar different from a sway bar or are they the same thing? Sorry if its a dumb question, but I'm just not familiar.

Thanks

[SWharton]

yes, they are different. We were amazed as was a friend by the addition of the track bar. We put on the Blue Ox bar.

 

PANHARD ROD/TRACK BAR: Panhard rods are generally called track bars and are typically straight bars, some do have a slight curve for specific applications. ... So, the difference is, the sway bar controls the leaning or top tippiness of the coach and the track bar controls the side to side movement of the coach.

[NoDirectionHome]

I'd like to correct/clarify if I may.  The Panhard bar locates the suspension position laterally and determines the roll center height and therefore it's stiffness in certain types of suspensions..  The anti roll bar (sway bar) determines ( adds to) the roll stiffness.  
       I think the Panhard bar would help considerably if you have a leaf spring rear suspension.

[TXiceman]

37 minutes ago, TexasJoePro said:

SWarton - Is a track bar different from a sway bar or are they the same thing? Sorry if its a dumb question, but I'm just not familiar.

Thanks

Actually, I always heard them called anti-roll bars on trucks and cars..

Be sure and add the stiffer bars to front and rear.

Ken

[Kirk W]

13 minutes ago, SWharton said:

yes, they are different.

I was about to post the same answer as his. The two are quite different and I suspect that you would see improvement with either one but the larger problem in most Ford chassis RVs comes from the track or Panhard bar because of the use of leaf springs which allow some lateral movement between the axle and the chassis which these devices prevent or at least limit that movement. 

If the budget were no issue I might consider adding both but I have found that most "experts" will advise the track bar first as the larger effect. Part n the issue comes from the fact that RV builders almost always extend the body of a gasoline powered unit beyond the manufacturer's frame rails. Doing this causes the effect of cross buffeting to increase beyond what it would if there were no extended body and so the need for equipment that was not part of the chassis as it was designed. 

[Lou Schneider]

Do a Google search for "E350 Caster adjustment".  A guy named Harvard claims adding additional positive caster to the front end alignment makes the E350 more stable on the highway, and he's generated discussions about this on a couple of message boards.

[oldjohnt]

Lou, I've owned a ton of the Ford E350 Class C's but in later years the E 450 Super Duty and it seems much more stable and less prone to wind and passing semi's. Perhaps Ford did something right????

 

John T

[TexasJoePro]

11 hours ago, Kirk Wood said:

I was about to post the same answer as his. The two are quite different and I suspect that you would see improvement with either one but the larger problem in most Ford chassis RVs comes from the track or Panhard bar because of the use of leaf springs which allow some lateral movement between the axle and the chassis which these devices prevent or at least limit that movement. 

If the budget were no issue I might consider adding both but I have found that most "experts" will advise the track bar first as the larger effect. Part n the issue comes from the fact that RV builders almost always extend the body of a gasoline powered unit beyond the manufacturer's frame rails. Doing this causes the effect of cross buffeting to increase beyond what it would if there were no extended body and so the need for equipment that was not part of the chassis as it was designed. 

Kirk & SWarton - 

My length is 25 foot (bumper to bumper) on the RV. Sounds like the track bar will probably give me the best bang-for-the-buck, so I will look into that first. **I can only wish budget were no issue!** Also, I failed to mention that I flat tow, via a blue ox towbar, a Nissan Frontier pickup with a camper shell (my garage!) which probably contributes to making the shorter rig "feel" longer on the road. I have weighed both the RV and the truck spearately, so i am confident I am within both GVWR and "Train Weight," but it does add another 20 feet of "wind catching mass" when towing, which I imagine doesn't help the situation.