Sway bars explained
Basically sway bars reduce roll and dramatically improve handling. They connect one side of the suspension to the other with attachment points generally on the lower A-arms and frame (chassis), and twist to limit the roll during cornering. As the truck enters a corner, centrifugal forces create a body roll force. This force is limited by the twisting actions of the sway bar. The stiffer the sway bar, the more resistance is extended to counteract the body roll. Too much sway bar stiffness creates excess pressure on the outside loaded tire causing a loss of traction. Sway bar stiffness is calculated by the force required to twist one end versus the other and calculated in lb-in.

Sway bars work off of torsional force (twisting motion). Therefore, the material in the center of a solid bar plays little role in the resistance of torsional force. With this in mind, hollow bars eliminate some of the center material and move it to the outside of the tube, where it is most effective. In turn, this produces a sway bar that is lighter in weight and just as stiff, if not stiffer, than solid. For example, a 13⁄8-inch hollow bar is equivalent to a 1¼-inch solid. But the 13⁄8-inch hollow bar is 6-percent stiffer and 43-percent lighter than the 1¼-inch solid.

Years ago, most trucks were only equipped with a front sway bar. Back then, the best tires were skinny with relatively soft sidewalls. Today people are running modern super-sticky tires. These tires produce serious grip and are much better than yesterday's race tires. Your truck will be the quickest and most comfortable around a corner or on your favorite twisty road with a neutral handling balance. This is achieved when the car is neither loose nor tight (excessive understeer or oversteer), but balanced with the front and rear tires doing equal work. Providing that the springs are of sufficient rate to keep the car from bottoming out, the handling balance is tuned with the front and rear sway bars. When talking to suspension designers at Hotchkis Performance, they said they typically engineer the largest front sway bar possible that doesn't overpower the front suspension and then tune (change roll stiffness) with an adjustable rear sway bar.

Some people recommend running a stiff rear spring combination without a rear sway bar. In this case, the heavy spring rate keeps the chassis from rolling, thereby eliminating the need for a rear sway bar. This is fine if the passengers wear kidney belts and interior rattles are no problem, but most truck owners know that a stiff rear spring and an unloaded bed can be brutal on long hauls. The rest of us want a comfortable ride with great handling. Adding a rear sway bar solves the ride quality issue and creates an optimum handling balance. The rear spring rate can be softer for better ride quality and corner exit traction because the rear sway bar (not the springs) is controlling the rear body roll.

Now that we know sway bar roll stiffness minimizes body roll, to make the truck handle well and remain balanced during cornering the front and rear sway bars must be tuned to work together. Well-designed sway packages offer balanced handling and are adjustable to fine tune the handling characteristics to the driver's preference. The adjustment is accomplished with holes in the sway bar end that allows the endlink to be positioned in multiple locations effectively lengthening (softening) or shortening (stiffening) the sway bars. Due to the endlink mounting location and reduced benefits of an adjustable front sway bar, companies like Hotchkis Performance often design the adjustable rear sway bar to be between a two- and four-hole difference. The adjustment holes give the driver a great tuning advantage because each hole is at least 100 lb-in difference.