A sway bar is a vital component of any car’s suspension system and it helps in stabilizing the vehicle while cornering by reducing body roll. It is also referred to as an anti-roll bar or a stabilizer bar and is essentially a metal bar which connects both the ends of the suspension. This is also a popular mod for people who are looking to drive their cars spiritedly or take it on the track and most modern cars have a sway bar. They also allow suspension engineers to set up a car’s handling and are not only beneficial for race cars but significantly improve handling of road cars and even large off-road trucks which might benefit with better drivability on the road.
When cornering, the outside wheels have to travel a larger distance compared to the inside wheels. The weight of the vehicle shifts inducing body roll which is undesirable. It is important to keep this body roll in check as it affects the ability of the vehicle to take the corner and this is where the sway bar will come in to control this body roll and stabilize the vehicle. While it might look like a simple piece of metal, a sway bar is very interesting in the way it works.
How does a sway bar work?
Sway bars are usually steel tubes which have lever arms at the end of it. They attach to the control arm via end links, connecting both the ends of the suspension. The sway bar itself is suspended by bushings which are attached to the frame of the vehicle. This allows it to move independently.
When both sides of the suspension are moving together, the sway bar sees no action but one when one side of the suspension is under load, like when cornering, the sway bar twists and tries to compress the other side of the suspension as well. The sway bar will allow the inside wheels to be in more contact of the road since it is compressing that side of the suspension, allowing for better grip and stability. The weight of the vehicle is distributed to all the wheels, and the body roll is reduced. The stiffer the sway bar, the higher the roll stiffness and it essentially increases the spring rate of the suspension.
This in turn affects the handling and one can get away with softer suspension to make the vehicle more compliant while adding in a stiffer sway bar to reduce the body roll of the vehicle. One can also alter the handling characteristics of the vehicle to either understeer or oversteer by adding a stiffer roll bar at one end of the vehicle. In off-road conditions, one might not need so much stiffness and some cars are offered with a sway bar disconnect like the Jeep Wrangler Rubicon and the Ford Bronco. It is a balance of suspension tuning and what one needs from a car which determines the stiffness of the sway bar.
