Driving over twisting highways, undulating backroads, and off-road terrain can tire out a driver and passengers when the vehicle is constantly tossing from side to side with every turn of the steering wheel. A sway bar can address the issue on vehicles with a high center of gravity, such as pickups with slide-in campers, camper vans, and motorhomes.
While shocks help control the vertical movement of springs, sway bars help reduce the side-to-side pitching or rocking motion during cornering, driving over uneven terrain, or encountering off-camber road irregularities, all of which are common for those who use their vehicles for camping and overlanding.
It’s worth noting that for most motorists, the term “sway bar” is synonymous with the more accurate “anti-sway bar.” Over time, the name of the part has been generally shortened, and most people simply call it a sway bar. Call it what you will, but the purpose remains the same.
“Most RV and camper van drivers don’t realize that a large portion of their handling issues actually come from sway,” said David Robinson, the V.P. of Roadmaster Inc. “Because you’re sitting so high up in the vehicle, even small amounts of sway feel like the vehicle is moving side-to-side in the lane, which leads to constant overcorrection and driver fatigue.”
“A properly engineered anti-sway bar stops that motion at its source, so the vehicle tracks straight and the driver [and passengers] arrives far more relaxed and in control — often to the point where a once-reluctant co-driver is finally comfortable taking the wheel.”
How Does a Sway Bar Work?
Sway bars are very simplistic in design and function. They are made from round steel bar stock, typically chromoly or alloy, that has been tempered to become a torsional-type spring. The thicker the bar, the stronger its spring action.
The bar is attached to both the rear axle housing and the vehicle’s frame or body via a link (sometimes called “motion arms”) at each end. Some vehicles have a second anti-sway bar up front. It all depends on the vehicle design and how much or little the vehicle manufacturer (or vehicle owner) feels the installation of anti-sway bars is needed for each application.
As the weight of the vehicle leans toward the outside of a corner or the low side of the road, the anti-sway bar at that end is pushed down as the suspension compresses. Because the sway bar is a torsional-type spring, the opposite end of the sway bar resists, simultaneously pulling downward on the vehicle’s frame. This resistance helps reduce excessive body lean.
They Reduce Fatigue
“The ride and handling of an RV plays a big role in the level of fatigue the driver and occupants experience after spending hours on the road,” explained Tommy Henderson, who oversees the design and development of anti-sway bars for SuperSteer.
“The more the van, pickup/camper combo, or motorhome rocks from side-to-side on the highways, byways, or backroads, the more stress it places on everyone inside as our bodies naturally react to maintain balance in the seats,” he said.
In addition to vehicle sway affecting the driver’s level of fatigue, the constant side-to-side rocking and body lean also place stress on the vehicle’s structural components, as well as drawer and cupboard latches, furnishings and appliances, and any loose or fragile items onboard.
Upgrading Anti-Sway Bars: A Benefit
That’s why most motorhomes, camper and conversion vans, and pickups come equipped with factory-installed sway bars. Some come with anti-roll bars on both the front and rear of the chassis.
But like OEM shocks and steering stabilizers, factory-installed anti-sway bars may not deliver the vehicle control an owner wants or needs for their particular vehicle and use.
Hence, upgrading anti-sway bars is typically one of the first “fixes” that RVers, outdoorsmen, and overlanders make to their vehicles. Roadmaster, SuperSteer, Hellwig, Eibach, and other suspension experts have invested significant R&D time and money in manufacturing aftermarket anti-sway bars for that very reason.
“The larger, heavier, and taller the vehicle, the more important it is to have a really good anti-sway bar working for you while you’re cruising down the highway or venturing off-grid,” adds Robinson.
Thickness Matters
What’s the difference between the OEM anti-sway bar and the heavy-duty aftermarket replacements? There are many factors, from the type of alloy they are made from to the diameter of the bar stock to the length of the motion arms that attach the bar to the frame to the type of material used in the bushings that hold the bar to the axle housing.
The diameter of the bar stock is one of the biggest difference makers. In general, for every 1/8-inch increase in an anti-sway bar’s diameter, the resistance to controlling body roll increases by about 33%, according to those who build anti-sway bars. And if the anti-roll bar undergoes a second heat-treatment process, as with some of SuperSteer’s RV products, the torsional rigidity of the factory unit is almost doubled.
For example, the SuperSteer SS110 anti-sway bars, which are built and tuned exclusively for specific RV and camper van applications, showed the thicker, stronger anti-sway bar reduced body roll by almost 60% on a 2021 Winnebago Navion Class C. Consequently, cross-country road tests revealed the upgraded anti-sway bar also reduced the adverse effects of wind gusts and side winds typical when driving across the desert southwest and mid-America.
Anti-sway bar manufacturers say similar results have been seen when installed under Mercedes-Benz Sprinter, RAM ProMaster, and Ford Transit vans converted to expedition-style campers. The same is true for camper-carrying pickups or pickups hauling ATVs on bed racks that have aftermarket anti-sway bars installed.
Anti-Sway Bars: An Easy Install
Installation is a relatively simple, straightforward job that anyone with basic mechanical skills and a socket set can handle. Most installs take between 1 and 2 hours. Of course, having the vehicle raised on a hoist is a great benefit.
The instructions that come with most of the well-known suspension manufacturers’ kits are detailed and well-illustrated.
Installing a replacement bar, or installing one on a chassis that doesn’t have one, takes a little more time than replacing shocks or a steering stabilizer because of the added hardware needed to attach the anti-sway bar to the vehicle.
A Final Thought on Sway Bars
“People expect some kind of improvement when they upgrade anti-sway bars, but they are genuinely shocked at the difference anti-sway bar upgrades make in how their vehicle drives and rides,” says Robinson. “Roadmaster manufactures a lot of different suspension components, but we receive more ‘Thank You!’ letters related to anti-sway bar installations than all our other products combined.”
