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. Here are all the bars we tested. Starting at the front and moving back, we have the stock 15/16-inch solid bar, 11/4-inch tubular, 11/4-inch solid, 1-inch solid stock rear, and finally a 11/8-inch tubular bar that Norrdin got from Hellwig. Here are all the bars we tested. Starting at the front and moving back, we have the stock Test 1 * 6.73 seconds = 42.7 mph * Stock front bar * No rear bar Test 1 * 6.73 seconds = 42.7 mph * Stock front bar * No rear bar Before we added anything to Ed's combination, we needed to get a baseline. The front suspension consists of Negative Roll upper and lower tubular control arms, tall spindles, street series S-13 coil springs all from Global West, and a set of Edelbrock Classic IAS shocks. The front suspension consists of Negative Roll upper and lower tubular control arms, tall The rear has adjustable upper and tubular lower control arms with an S-60 coil springs from Global West and another set of Edelbrock shocks. The rear has adjustable upper and tubular lower control arms with an S-60 coil springs fro The car has a stock 15/16-inch solid bar that is rated at 156 pounds. During the test the car had a noticeable amount of body roll and was a handful to control, Licata says. The car has a stock 15/16-inch solid bar that is rated at 156 pounds. During the test the Test 2 * 6.46 seconds = 44.7 mph * Hollow front bar * No rear bar Test 2 * 6.46 seconds = 44.7 mph * Hollow front bar * No rear bar Norrdin and Zinke swapped the stock bar for the 1-inch tubular/hollow bar that has a 413-pound rating. The added rating on this bar compared to the stock bar was almost instantly noticeable, and the car stayed pretty flat through the slalom. Licata was able to push the car harder and shaved off 0.27 second from the time. Norrdin and Zinke swapped the stock bar for the 1-inch tubular/hollow bar that has a 413-p Test 3 * 6.30 seconds = 45.5 mph * Solid front bar * No rear bar Test 3 * 6.30 seconds = 45.5 mph * Solid front bar * No rear bar A solid 1-inch bar with a rating of 542 pounds was put in place. The stiffer rate on this bar also helped keep the car flat allowing Licata to shave off another 0.16 second from the previous test. Licata reported that the car felt a little harsh and really got upset when the road got bumpy in the turn around area of the test facility. "A sway bar, whether it is hollow or solid, does not make a difference with ride harshness. It is the rate (stiffness) of the bar that contributes to ride change. You can have that with solid or hollow." A solid 1-inch bar with a rating of 542 pounds was put in place. The stiffer rate on this Test 4 * 6.55 seconds = 44.1 mph * Solid front bar * Solid rear bar Test 4 * 6.55 seconds = 44.1 mph * Solid front bar * Solid rear bar Now that we had the front dialed in, Norrdin and Zinke installed a stock configuration 1-inch solid rear bar that bolts to the lower control arms and is rated to 1,333 pounds. Thinking we were going to see some fast numbers we were surprised to see the car slow down. "The roll center in the rear of the Chevelles is high. Any increase in roll stiffness pertaining to spring rates, sway bars, or improper bushings will cause less traction and increase oversteer. You will also limit the amount of power you can put down in a corner. It will help in a drag racing scenario. Because the bar ties both lower arms together it helps transfer load to the other tire as the weight transfers." Now that we had the front dialed in, Norrdin and Zinke installed a stock configuration 1-i Test * 6.43 seconds = 44.7 mph * Solid front bar * Hollow rear bar Test * 6.43 seconds = 44.7 mph * Solid front bar * Hollow rear bar The pit crew installed a Hellwig 11/8-inch rear bar that mounts to the axle tube and to the frame, not the lower control arms and is rated at 321 pounds. With this setup installed the times got better than the stock-style bar by 0.10, but still couldn't best the times without any bar at all. "When mounting the rear sway bar from lower arm to lower arm (stock configuration), the input from road irregularities, bumps, etc. directly upsets the other side. The lower arms and the rearend are now tied together, so movement is restricted. Restrictions in the suspension increase the roll stiffness that affects the cars handling. Therefore the rear sway bar (the bigger it is, the worse it is) causes the inside tire to lift during cornering, thus increasing oversteer and reducing the cars capability to put power down. A sway bar that attaches to the differential and has the endlinks attaching to the frame does not have the same affect on the lower arm." The pit crew installed a Hellwig 11/8-inch rear bar that mounts to the axle tube and to th "The '64 Malibu had a fairly soft front spring for autocross applications. The front spring rate was stiffer than stock (Performance Street) but nowhere near the rate needed for autocrossing. The test track was also smooth. A solid 1 1⁄4-inch front bar has a greater rate (stiffness) than a hollow bar given the same OD A hollow bar is lighter (great for racing) but a 11/4-inch hollow bar is about the equivalent to a 11/8-inch solid, (a rate less than the 11/4-inch solid). Since the roll stiffness of the front end on the Malibu was soft, a 11/4-inch solid bar will increase the roll stiffness closer to an autocross application giving you better cornering. However, this is not to say big bars work for everything. On a smooth course, the larger sway bars work, but on rough courses, the larger bars tend the make the car less forgiving. The suspension will not absorb the larger bumps and the car can and often does go into understeer." "The '64 Malibu had a fairly soft front spring for autocross applications. The front sprin 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 SOURCES Global West Suspension 655 S. Lincoln Ave. San Bernardino CA 92408 877-470-2975 909-890-0759 http://www.globalwest.net By Calin Head Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!