Torsion Bars & Components

Like their coil and leaf counterparts, torsion bars are springs. However, instead of compressing like a coil spring or deflecting and flattening out like a leaf spring, a torsion bar twists when loaded. Torsion bars are spring steel rods with one of the ends mounted to the frame and the opposite ends attached to the suspension, usually the lower control arms. Torsion bars have been transversely mounted on some vehicles in the past but today they are more commonly mounted longitudinally.

Torsion bars can be either splined or hex-shaped where they attach to the frame and control arms. The frame ends are typically mounted in a key, also called an anchor or adjuster, which enables adjustment of ride height. At normal ride height, the torsion bar twists a certain amount supporting the weight of the vehicle, and twists further when the wheel strikes a bump and moves upward. After the bump, the torsion bar unwinds, forcing the tire back down.

The spring rate, or resistance to twisting, of a torsion bar is determined by the material it’s made of, and its diameter and length. Many late model trucks and SUVs, especially 4WD models, have longitudinally mounted torsion bars. This configuration enables the use of long torsion bars that have a wider twisting range, allowing more suspension travel that is useful when off-roading. Torsion bars also take up much less space on such vehicles, so drive axles can be easily located where coil springs would get in the way.

Torsion bars are generally very reliable components, but like any type of springs they can eventually become fatigued, which can negatively affect ride height, handling and wheel alignment. However, because they are typically mounted low on the underside of the vehicle, they are also susceptible to impact damage from obstacles and road debris. The torsion bars on vehicles that are driven off-road should be inspected for bends, cracks, and scrapes, which could make them ineffective or decrease their lifespan. Many torsion bars have rubber cross member mounts, and these can wear and cause noise.

Torsion bars are lighter and more compact than coil springs or leaf springs, but their primary advantage is that they can usually be adjusted. Unlike sacked coil springs that must be replaced, bolts at the keys on the torsion bar ends can be turned to raise ride height, or tune the height so it is even side-to-side. Proper ride height is critical to good handling, and to maintaining alignment angles for even tire wear. However, sometimes the range of adjustment is inadequate to bring ride height within specifications. We offer replacement key assemblies that increase the adjustment range, so ride height can be restored or even increased if desired – raising the front-end ride height to level the stance of a pickup truck for example.