When I am helping friends with their vehicles, I am often asked how to make a car handle better. You can have all the horsepower in the world, but if the suspension isn’t up to snuff, horsepower is useless. Techniques used to make race cars handle better also make street vehicles more stable and safer.
Springs are usually the topic of conversation when it comes to handling but control bars are often the difference between good handling vehicles and those that tend to “fall over” in a corner. Both sway bars and panhard bars are used for suspension control, but the purpose of each is often confusing. They are used for entirely different purposes.
Panhard bars are one device that can be used to locate a solid rear axle under a vehicle. The bar is mounted across the vehicle, with one end connected to the rear axle housing and the other end connected to the body. During cornering or sideways movements of the vehicle, the bar keeps the axle located laterally under the body. Panhard bars should be as long as possible for the best handling because this reduces the effects of lifting the body that a short panhard bar can cause.
Independent rear suspensions do not need a lateral bar to hold the axle in place, and some vehicles with solid rear axles do not use a panhard bar. The rear axle may be held in the proper location by leaf springs, control arms mounted at a V-shaped angle, or even a Watts linkage. The Watts linkage is a type of panhard bar but it uses a swivel linkage in the middle to reduce the body lift effects.
Better angles, higher traction
Sway bars are used to reduce body roll or lean during cornering. Almost all vehicles are equipped with a front sway bar, and many performance vehicles have a rear sway bar too. Sway bars are wide U-shaped bars with the bottom of the U often mounted to the body with bushings and the arms of the U mounted with links to the suspension. When a wheel moves up on one side of the vehicle, the spring steel sway bar lifts the wheel on the other side of the vehicle. The added weight on the other wheel keeps the vehicle body relatively flat, making the suspension angles better for higher traction.
There is a lot of science to sway bar selection. The strength of the bar must be matched to the weight and size of the vehicle. Professional racers will use different size bars to help tune the suspension. An increase in sway bar diameter of even a few thousandths of an inch will make the bar significantly stiffer. Some bars are hollow tubes, while others are solid steel. The length of the arms on the sway bar also make a difference. Short arms have less leverage, so the bar is stiffer. Some aftermarket sway bars have adjustable positions for the connecting links at the ends of the bar to adjust bar strength.
Although few modify the suspension on their vehicle, adding a rear sway bar to yours may be simple, but if the front and rear are not matched, the vehicle will have different traction levels at the front and rear. This can make the car swap ends very quickly. When installing a sway bar, use both the front and rear bars from a high performance version of the same model car, or select a matched set from aftermarket suppliers.
Maintaining good handling in your vehicle is not difficult. Sway bars mount to the body in flexible bushings. If these are cracked or broken, they need to be replaced. Connecting links at the ends of sway bars connect the sway bar to the vehicle suspension. These links connect with flexible joints or rubber bushings.
If one of the links breaks, which happens occasionally, then the sway bar has no control of body roll. Replacing the link is a quick and economical repair. Shock absorbers and struts wear and don’t control suspension movement as well. Replacing them with new heavy duty components can have a dramatic effect on improving handling and ride.
Also, keep tire pressures at recommended settings and check them at least once a month or more frequently if outside temperatures change dramatically. Low tire pressures will make any vehicle handle badly.