Just to clarify some terms, as in this case using the correct terms does make a difference. If the problem is not correctly defined, it is hard to get the correct solution.
An ANTI-SWAY bar is one that laterally links a solid axle to the chassis. One ends connects to the axle and goes across the center line of the vehicle, connecting to the chassis on the other side. Why is this different from an anti-roll bar ? Because it keeps the chassis centered over the axle, preventing the vehicle from moving side to side in all conditions, not just when turning .
This is very different from an ANTI-ROLL bar which resists the chassis "leaning over" or "rolling" down toward the outside of a turn. An anti-roll bar will come into action during cornering to resist or limit the chassis from "rolling" as if on a barbecue spit. It will interact, as Gerald correctly notes, with the springs or air bags that hold up the entire vehicle. There can be complications if not correctly matched to the springs or bags. The springs or bags do resist roll, but their ability to do so has to be compromised to keep the ride comfortable.
Technically, an anti-roll bar only works when the chassis is rolling as one side of the suspension goes up and the other resists that. When hitting bumps, both sides go up with the suspension so no effect. All fine until hitting a bump with just one wheel, then the bar adds to the stiffness of the springs or bags.
On the other hand, if the vehicle is "wandering" down the road and feels like the whole coach is moving side to side, especially when traveling in a straight line, an anti-sway bar MAY help. I have seen add on bars for front axles on some class A's. However it is necessary to make sure that the wandering is not the result of steering action rather than axle movement under the chassis.
Unfortunately many chassis manufactures pay little or no attention to how axle movement affects the toe in settings on both sides and a lot of the "wandering" is because the wheels are moving in and out differently side to side which is know as "Bump Steer" and has the same affect as constantly moving the steering wheel. This requires constant steering corrections.
An example was the old GM P chassis that many class A's were build on. When they widened the chassis rails they didn't change the steering parts which causing the wandered all over the road. A friend of mine actually produced a kit that corrected the problem and the difference was night and day.
All this is why it is important to define what the problem is or else one can make the problem worse or waste money and time on something not needed. These principles are the first things I have had to teach budding race engineers over the years and why it is important to know the correct terms.
Racer Bob
