Handling: Rocking and Rolling: UPDATE

Be nice if you knew a shop dedicated to servicing U=Haul trucks and talk w/ their Chevy suspension know-it-all.

Snowman9000 wrote:
Our Sunseeker 2300 Chevy sure pitches side to side a lot when we encounter any bumps at all while turning at slow speed, such as leaving a parking lot....

As others have stated, the difference in height can make a difference in rocking side to side. That A/C on top is about 7" higher than on your previous motorhome. A 2005 RVision Trail-Lite 213 was 10'-8" while the 2014 Forest River Sunseeker 2300 is 11'-3". You also have a much heavier looking cab-over. I'm fairly certain that your Trail-Lite gas tank was lengthwise and between the axles and so was your fresh water tank.

Handbasket probably has the best suggestion of varying the air pressure in your air bag. I would start by dropping the pressure from 50 to 40, then 30...until 10 psig. I doubt you need to be above 50 as that 4500 should have enough spring to hold your weight.

Beefier sway bars will also benefit in parking lot dips as well as on the open road. As j-d stated, they will also stabilize the rig when parked. People walking around inside will have less effective motion on the vehicle.

Everyone can easily experiment on their own motor home's rear sway bar very simply (and fun) to determine effectiveness. Have a few family members stand together inside the motor home over the rear axle, all members facing forward. Have them work together trying their best to rock the rig side to side by shifting their weight left to right in unison. An effective rear sway bar will lower both rear corners simultaneously regardless which way the weight has shifted. If you had no rear sway bar, one corner would raise up when the other rear corner went down. You can sight it best looking at the relationship between the rear tire and RV body.

A lesser rear sway bar will lower both rear corners, but not as much as a heavy duty bar would, hence you will still feel the rig rocking.

You could also perform this experiment on the front axle but because people can't stand directly over the front axle, you might not be able to get enough rocking motion to see the results. Still it would be worth a try.

When I perform this experiment on the rear of my own rig with Roadmaster heavy duty sway bars, I feel the entire rear of the motor home drop regardless of how I shifted my weight. I simply cannot get the rig to rock side to side. It gets cancelled out by dropping the entire rear of the rig by some amount.

Interesting discussion....

My 23 foot Jamboree has airbags, a single fill point & air pressure gauge on the trailer hitch. I can understand how having each side linked via common tubing might contribute to racking & pressure transfer. I may separate the lines & see how it goes.

You can see how the previous owner mounted it here-



Previous owner said he kept the pressure at 50 psi and that is where I have kept it. The ride in the rear is pretty harsh though so I'm going to experiment with different pressures.

ron.dittmer wrote:

You are the first person in the 7 years I've been on this forum who mentioned a sway problem on their Chevy chassis. Either you have a unique problem or nobody else with a Chevy wants to discuss it.

I don't consider my Chevy to have a sway problem. Some minor rocking at the slow speed driveway type movement that Snowman is talking about, but nothing that concerns me. I've been following this thread to see if I'm doing anything different. I do travel with a full fresh water tank most of the time, and generally start trips with full fuel and refuel at about 1/2 tank. Holding tanks mostly empty. I usually start air bags at 60 psi. Add a little air if I know we are going to be facing strong cross winds.

Maybe the shifting of partially full tanks is the difference. Maybe the air bags need a little more air.

Ron, it's not sway going down the road, from wind and trucks etc. It handles pretty well on the road. It's rocking like a boat when something bumps the back end up or down while traveling at parking lot speed. That still might be fixed by a sway bar. The rear bar looked like it is ~1 & 3/8ths. Don't recall the bushings. Probably rubber.

jd, the tanks are crossways. It is something I'm going to be paying attention to, although the way we travel, water will be present.

Your gasoline tank, furnished by Chevrolet, may be baffled inside. Even if not, it's probably installed lengthwise in the chassis, so gasoline shifted side to side doesn't have all that far to "slosh." Are your water tanks (fresh, gray, black) installed crosswise under the coach body?
This may sound counterintuitive, but a warship with a damaged, partially flooded compartment will often choose to flood it fully. The partially filled compartment is more de-stabilizing than it would be fully flooded despite the additional weight. It's called "Free Surface Effect." If you had three tanks, each half full, mounted crosswise, I think you might feel the surge of the combined weight of the water.

Snowman 9000,

Of coarse you'll want your rig to handle properly when you are loaded up on vacation with your precious cargo, rather than running around town empty. You are on-track to get it figured out.

If you conclude that you need to take next steps, J-D was "On The Money" with his inputs I included below. You know so well that he and I support the use of heavy duty sway bars on our Fords. We are assuming the Chevy will benefit the same. I am not sure Hellwig and Roadmaster sell heavy duty sway bars for the Chevy/GM chassis. I also wonder how the stock Chevy front & rear sway bars compare dimensionally and bushing type, rubber or polymer.

You are the first person in the 7 years I've been on this forum who mentioned a sway problem on their Chevy chassis. Either you have a unique problem or nobody else with a Chevy wants to discuss it.

j-d wrote:
We replaced our skinny OEM sway bars with much larger Hellwig bars and the changes were only for the better. In theory there can be "too much sway bar" but I believe it pertains to cars and racing, and there is no practical limit for motorhomes. Being as they are very high, making them topheavy, and not driven to extremes.
Does it sway when parked on a campsite and people are moving around? You'll always feel movement in a Class C but if it wallows like it's driving on the road, stiffer sway bars will help greatly.

Ichabod, the thing I thought about the airbags is that maybe they are a way to give the 4500 a soft-enough ride on the smaller MHs. Put slightly soft springs on, and then let the owner stiffen it up to suit with the bags. Because, it does ride nice when empty, for a small rig on a 4500 chassis.

Your report is encouraging. Is there more than one Bilstein model for these? EDIT: I checked and even called Bilstein. They do not make a shock for the current 4500's. :(

I think you are on the right path, as you said your old rig was shorter and lower to the ground. This one is taller and with the higher center of gravity and added fuel and water placement behind and above the axel they will tend to sway more.

Mine on a Chevy chassis did the same somewhat, getting that boat rocking, back in forth, back in forth motion. After I changed out the OEM shocks to Bilsteins It only makes one slight roll then returns to center, It seemed to be a better damping effect in the side to side roll. They really helped in that and the porpoising effect. I also do not have any airbags, but mine is small and I don't tow so I have no use for them.
They would seem to be overkill on a small rig where the axel weights and GVWR are well under the max limits as mine are.

Good luck in finding a solution, I hope that this may be of help.