Only Mopars of the ’60s and ’70s used torsion bars instead of coil springs to support the weight of the car’s front end. This month we’ll explain how they work, which ones are right for your car, and demonstrate how easy they are to change.
Of all the domestic auto manufacturers building cars during the '60s and '70s, the Chrysler Corporation was known for their innovative engineering and willingness to think "outside the box," as they say. One of the ways Chrysler engineers exhibited this attribute was through their extensive use of torsion bars, rather than coil springs, to support the front suspension of their passenger cars, giving the cars a stable, true-tracking ride and the ability to easily change the vehicle's ride height. And while most of us know what a torsion bar looks like, this month we'll explain how they work and give you some pointers to help you pick the right torsion bars for your Mopar.
1 Torsion bars (bottom) are...
1 Torsion bars (bottom) are simply springs that work via a twisting motion, supporting the car’s weight like the leaf springs shown above. Larger diameter bars like the ones shown here from PST suspension will give your car a stiffer ride, improved handling, and improved braking.
While a car's suspension has many parts that make it work properly, it can be broken down into two basic components, with two separate functions. The first component is a spring of some type must support the car's weight, and most cars from the muscle car era use a leaf spring for this purpose in the rear. Up front, a coil spring can be found in most domestic vehicles, but Chrysler chose to use a torsion bar instead. Whichever type spring is utilized, however, it is rated with a weight (or tension in psi), which is generally the pounds it will support, and a rate, which means that as the coil spring is compressed (or leaf spring is straightened, or torsion bar is twisted) the spring weight will increase for a certain amount of spring movement. And while the spring (or torsion bar) supports the weight well, it can't do its job properly without the second suspension component, the shock absorber.
A shock absorber is actually a dampener, and doesn't support the car's weight at all. When the wheels ride over a bump or the car leans around a corner, the spring is loaded and wants to rebound back to its original position. The shock absorber dampens the rate at which the spring can act, keeping the spring from oscillating up and down after the initial compression. Mopar front suspension contains both a shock absorber and spring for each wheel, and up front the spring is in the form of a cylindrical bar called a torsion bar, which provides a spring action when twisted.
2 A byproduct of the torsion...
2 A byproduct of the torsion bar’s design is the ability to quickly change or adjust ride height by tightening or loosening the torsion bar adjuster nut. To change the torsion bar, this adjuster bolt is simply loosened completely to relieve the tension on the bar.
Chrysler torsion bars came in many lengths and diameters, depending on body style, engine option, and handling package, but can basically be narrowed down to three bars. The Slant-Six torsion bar came in six-cylinder equipped vehicles and is the smallest diameter, lowest weight torsion bar Chrysler offered from the factory. Small-block V-8 cars got a slightly larger diameter bar, and big-block and Hemi cars got the largest diameter factory torsion bars. Though not as prone to wear as other types of spring, torsion bars do wear over time, so replacing them with new torsion bars from a company like PST Suspension makes sense during a suspension rebuild. This is also a good time to decide whether a factory weight torsion bar is right for your car, or a softer or stiffer set of torsion bars would be best.
Like coil and leaf springs, torsion bars can be used for suspension tuning, and choosing the right one greatly depends on the use of the vehicle. For a street car, we generally prefer a larger diameter, stiff torsion bar up front to limit body roll and improve handling and braking. Ride quality will be a little harsher with a stiff bar, but we feel the added performance is worth the sacrifice. For a drag race only vehicle, a lighter bar such as the Slant-Six unit has always been a preferred choice among chassis tuners since the light spring allows the front of the car to rise rapidly, transferring weight to the rear of the vehicle for improved traction. Whichever torsion bar you decide is correct, Mopar owners are lucky to be able to swap bars easily due to the design of Chrysler's front suspension. Follow along and we'll show you how quickly you can change your car's torsion bars.
Price: PST high-performance torsion bars: $219
3 Getting the old torsion...
3 Getting the old torsion bars out requires removing the c/spring-clips at the rear of each bar, and driving the bar rearward. If you plan to scrap the old bars, a pipe wrench can be used but will gouge the outside of the bar. We prefer this nifty tool to remove and install torsion bars, which is also available from PST.
3 Getting the old torsion...
3 Getting the old torsion bars out requires removing the c/spring-clips at the rear of each bar, and driving the bar rearward. If you plan to scrap the old bars, a pipe wrench can be used but will gouge the outside of the bar. We prefer this nifty tool to remove and install torsion bars, which is also available from PST.
3 Getting the old torsion...
3 Getting the old torsion bars out requires removing the c/spring-clips at the rear of each bar, and driving the bar rearward. If you plan to scrap the old bars, a pipe wrench can be used but will gouge the outside of the bar. We prefer this nifty tool to remove and install torsion bars, which is also available from PST.