Torsion suspension bars, which are common in trucks, bear the weight of the vehicle much like coil springs do in smaller vehicles. Torsion bars can be "leveled" or "dropped" to raise or lower the height of a vehicle. Truck owners prefer to do this themselves because torsion bars are easily adjustable, and because there is usually a need for an owner to compensate for heavier or lighter engines or loads. What makes this adjustment easy is a small lever at the end of the torsion bar: mounted perpendicular to the bar that is attached to a suspension arm is a simple mechanical part called the torsion key.
What to look for in a torsion key
Although a stock torsion bar key is available, it has a limited range to which you can raise or drop your ride height, and might also affect your ride if you plan to change tires. Here is a list of questions you should ask yourself before deciding to buy a certain brand:
- Can it provide additional clearance when I change to larger tires?
- Is it durable, and how long is its service life?
- Is it easy to install?
- How high or how low (usually in inches) can it raise or lower my vehicle?
A torsion key's effect in ride height
A torsion bar's main function is to keep the wheel assembly from shifting forward and backward when you are driving on a rough road. With a torsion key attached to a torsion bar, however, you should also be able to change your ride height easily. A word of warning, tough: the ride will get stiffer when you raise the front end of your vehicle higher. Aftermarket torsion bar keys-also called "green keys"-will help you with this. Torsion keys can also restore ride height, which may have changed due to worn torsion bars, to factory specifications.