An anti-roll bar is a device found on an automobile that displaces the load across the front or rear suspension. By spreading this torsional stress across the entire width of a vehicle's suspension and chassis, the anti-roll bar aids in cornering traction and control. Without the aid of an anti-roll bar, the inside front tire of a vehicle could become airborne during a sharp turn while the rear tire on the outside of a turn could be subjected to too much force and eventually blow out. By placing weight and load stress on both sides of a vehicle equally during a turn, the anti-roll bar helps it to remain stable, level and more easily controlled.
In certain racing conditions, an anti-roll bar placed on the rear axle aids the vehicle in maintaining traction during rapid acceleration. In drag racing applications, the anti-roll bar places traction on both sides of the rear axle as the twist of the chassis from the engine torque is evenly displaced from one side of the axle to the other. This places more bite on both rear tires as the vehicle attempts to rotate around the center of the engine's torque at the drive shaft. Early racers used air bags placed on one side of the rear axle in an effort to stiffen the rear suspension and prevent the twist and resulting unloading of one rear tire. Science has shown that the addition of an anti-roll bar does a much better job of distributing the torque and providing adequate traction during take-off.
In circle track or road racing, the anti-roll bar applies weight and, therefore, traction to both sides of the vehicle during cornering. This aids in equal tire wear as well as vehicle control. Without the device, the outer tires would wear out much sooner and would result in frequent tire blow out. In automobile racing, race teams spend a great deal of money developing more efficient anti-roll bar systems. In addition to a vehicle's horsepower, the chassis is also a major factor for a racing victory or loss.
Many world-class race teams work hand-in-hand with automobile manufacturers and colleges in the development of their racing chassis and components. This development allows the manufacturers to apply the information to the production vehicle lines and models. As a rule, the larger the diameter of the bar, the stiffer the vehicle's suspension as it travels through a corner.