Finally, we wanted to upgrade and improve our rear suspension. When new, our ‘Bee, like any Mopar muscle car, came from the factory with a leaf spring rear suspension. Leaf spring design has come a long way since the tried and true Super Stock spring upgrade of the ’70s, but we decided to take advantage of a new mousetrap (so to speak). Unlawful Racing manufactures a triangulated four-link suspension that eliminates the leaf springs. In a leaf spring suspension, the springs perform two distinct functions. First, they hold the rear axle of the car in place, and secondly, they prevent both forward and rearward movement of the rear end. Under normal circumstances, they also minimize pinion angle change during suspension travel. Try to launch the car from a stop light, and the springs try to “wrap up,” changing the pinion angle. This causes wheel hop and loss of traction. Secondly, they also support the vehicle’s weight. For a stock vehicle that will operate within a predictable range of suspension travel, leaf springs do an adequate job. The problem occurs when the intended usage is changed (i.e. lower ride height, more horsepower, and/or different weight distribution characteristics). The leaf springs can’t perform as intended if the intended usage deviates far from the original usage. With a four link suspension, the function of locating the rear axle and supporting the vehicle are now done by two different pieces; the four link and the coil-over shock absorbers. With a four-link suspension you have the ability to properly locate the rear axle no matter how soft you want to make the spring on the coil over for ride comfort. With a leaf spring rear suspension, softening the spring rate can cause other problems such as a sagging rear end of your car, or an ill-handling car.
Installing the rear suspension and the roll bar do require a welder, and are a little more than a novice might want to try and tackle. The Chassis Stiffening Bars are a simple bolt-in design that can be welded in place, and will give the average Mopar a great improvement in its handling characteristics by itself.