If you have ever driven a sport-utility-vehicle (SUV) hard through the corners, especially if it’s a full-size family truckster, then you know that many of them tend to exhibit body roll as they go around the corner, and some even wag their tails quite a bit as they exit the corner. Some makes and models are better than others, but in general, the tail-heavy construction of a SUV, as well as its bias toward a soft cushy ride as opposed to a “sport” suspension tune make them typically handle looser than other types of vehicles.
Most are supplied with rear anti-sway bars from the factory to tone down this slushy behavior, but when pushed hard, the stock anti-sway bar can often begin to show its limits soon. The problem is, as Mark Hellwig of Hellwig Products says, “Most factory sway bars are a compromise.”
As the term implies, an anti-sway bar improves vehicle handling by working to limit body roll. In its most basic form, an anti-sway bar is a metal U-shaped device attached to both the frame and the axle (or suspension arms depending on the vehicle) on each side. As the body and frame are forced to roll during a turn, it twists the anti-sway bar (which acts as a spring), creating a torsional force resisting the lean.
To improve on the factory anti-sway bar, Hellwig offers bars with increased deflection rates of anywhere from 15 to 40 percent, depending on the application, and the bar’s diameter and length. Forged in a 2,200-degree furnace “the bars are made out of 4140 alloy, a bar stock that retains memory,” Hellwig said. “They return to their original shape when deflected. When the vehicle body starts to roll, the spring (bar) pulls the high side back down to provide more tire grip and help keep traction.”
Every action has a reaction, and as the body rolls back toward upright after the vehicle exits the turn, it wants to keep rolling past the point of perfectly upright. A good anti-sway bar can also act to resist the vehicle’s tendency to lean too far back the other direction as the body and frame go past upright.
We upgrade and improve the entire system, not just the anti-sway bar. – Ben Knaus
“When we design our bars, we try to get closer to a neutral steer than the factory bar, but still slightly biased toward understeer to maintain that safety margin. Our bars are also designed to help control a vehicle with a large load such as a trailer or when you have altered it with a lift and changed the center of gravity. A lot of it is a comfort thing too, preventing the roll from becoming exaggerated so the weight transfer is not so dramatic.”
“First, we determine if it came with a factory bar or not, that changes the way we go about this process. If it did have a bar, such as is the case with the Grand Cherokee, we are primarily making it bigger and stiffer than the factory bar, and finding out what we think will work best for the handling of the vehicle. We also make sure to use all the same mounting holes so it is easy to install.”
“The prototype bar is made. Then we install it and take the vehicle out and give it a really good test to see how close we are to where we think the handling should be. We test with and without a load, and with and with out a trailer. One we’ve seen how that prototype bar works, we may decide to go up or down in size to fine tune it.”
“It’s not just about going up in size. It’s also a matter of using better steel, and some OEMs bars are not heat treated. Our bars are heat-treated 4140 chrome-moly steel. We are not only changing the spring rate, but also making a more durable and longer-lasting bar. We also upgrade to polyurethane bushings in our kits to get rid of the factory rubber bushings, and re-engineer the brackets to make sure they are beefier too.” Knaus said, “We upgrade and improve the entire system, not just the anti-sway bar.”
We recently installed a Hellwig anti-sway bar on the rear end of a 2002 5.7-liter Hemi-powered Jeep Grand Cherokee and saw good results, so we thought we would talk to the people at Hellwig about its new product for the 3.0-liter EcoDiesel-powered Jeep Grand Cherokee. As expected, the install was easy, and took just a couple of hours.
The factory bar was removed by unbolting the hardware securing the bar to the crossmember, and then detaching the bar from the end links. The end links were left attached to the lower control arms. While the gas and diesel Grand Cherokee vehicles have some similarities, there are some differences in the way the undercarriage is laid out, and therefor some differences in the way Hellwig had to design the anti-sway bar for that vehicle.
For the diesel Grand Cherokee, we had to pry the rubber exhaust hanger off the post on the driver side, and disconnect the exhaust flange so the exhaust would hang down enough to allow more room for installation of the bar. Knaus said,”The diesel Cherokee had to have a slightly different design because of the rear end layout, as it’s really tight underneath the vehicle.”
“When we went up to a larger diameter bar, it began interfering with some of the suspension and exhaust components. We had to make new bends in the bar instead of just copying the factory bar. We had to adjust the shape of the bar to get it to fit.” The new bar was loosely installed on the crossmember using the new U-bolts and bushings, with the kit-supplied lubricant on the inside of the new bushings where they will contact the Hellwig anti-sway bar.
As we were making sure everything was tightened properly and cleaning up our tools, Knaus told us there were some myths about Hellwig anti-sway bars he wanted to bust wide open. “First of all our aftermarket anti-sway bars do not lift the vehicle. They help to control sway and roll, but it has no height adjustment at all.”
“The other one that we probably get once a week through out tech phone lines is about the ride. They think an upgraded anti-sway also going to stiffen the ride. It does not. If you hit a bump going straight down the road, our aftermarket anti-sway bar will not alter the ride quality. The only time the bar comes into play is when you are cornering or the body of the vehicle is rolling.”
We also noticed no apparent ride degradation when simply driving down the road. Even when encountering rough pavement, or small speed bumps (taken at slow speeds), the quality of the Cherokee’s ride was the same as it felt prior to the Hellwig anti-sway bar installation. So out the window goes that old-wive’s tale about anti-sway bars making the vehicle’s suspension stiffer. If you are interested in the Hellwig Products anti-sway bar for the diesel Grand Cherokee, or any of the many vehicle applications from Hellwig, check out its website or call (800) 367-5480.