Since getting your muscle car to carve corners and rip up autocross events has become the hot new thing, we wanted to explore one of the more common questions: "How big of a sway bar do I need?"
First of all, let's explain what a sway bar is. A sway bar is a suspension component used to reduce body roll during a cornering situation. It does this by tying the left and right lower control arms together with two pivot points on the frame. When the left and right suspension assemblies cycle together, the sway bar just pivots on the frame bushings and doesn't do much. It's when the left and right assemblies move independently that the sway bar is engaged, like when throwing the car into a corner. During a cornering situation, the outside suspension assembly is compressed up into the wheelwell while the outside assembly extends down. Since the bar is tied to the frame and to each control arm, the bar gets put into a twist and tries to equalize compression and extension in turns, thus keeping the car flat.
Armed with the basics of what a sway bar does, we are going to get into our testing. We had Super Chevy publisher Ed Zinke bring out his super-clean '64 Chevelle convertible as the test mule. The car features Global West suspension front and rear. It rolls on 15-inch Rally rims with P215/60R15 tires set at 33 psi at all corners. The car had a factory front sway bar and no rear bar.
We also invited suspension guru Doug Norrdin from Global West Performance and asked him to bring an assortment of sway bars for Ed's car, along with all that suspension knowledge stuck in his brain. Norrdin brought two different front bars and two different rear bars for comparison. To keep the driving consistent, we had our in-house West Coast hot shoe "Quick" Nick Licata pilot the car through the 420-foot slalom. Now that you know the parameters of our test, read on to see the results.
Hey Doug, What's Negative Roll?
"Negative roll is something we came up with in 1984. It is a combination of components that make up the geometry. Negative roll refers to the camber gain as the tire goes up into the fender. Negative camber leans the top of the tire in toward the engine. Positive camber is when the top of the tire leans out toward the fender. The factory geometry uses positive camber gain so that when the car goes through a turn and the tire goes up into the fender, positive camber kicks in and your handling is reduced. By going to a negative roll system, which are taller spindles and a special length upper control arm. Negative camber can be induced through the turns. The tire leans in toward the engine providing more footprint on the pavement, increasing the cornering ability of the car." -Doug Norrdin
Ed's Driving Impression
Before leaving the track, Norrdin recommended we install the hollow front bar and remove the rear bars for the best on-the-road setup. We asked Zinke the next day how the car felt on the drive home and here is what he had to say. "The hollow sway bar improved cornering significantly without affecting overall ride quality. Normal ride remained almost identical to stock bar with only a hint of being more rigid. It's a very subtle change that is comfortable with no harshness at all. In cornering, body roll disappeared and remained flat with improved entrance and exit speed throughout. The final combination greatly improved driveability and enjoyment." -Ed Zinke