Torsion Bar Adjustment
Both cars and trucks have torsion bar suspensions. They provide the suspension coil springs, and leaf springs offer with the added benefit of ride height adjustability. They can be designed longitudinally of transversely. Weak torsion bars or worn anchors and bushings alter the vehicle's ride height, affecting stability and causing tire wear.
A typical longitudinally designed torsion bar is a long steel bar fitted between the frame of the vehicle and one of the control arms. It may be the upper or lower control arm, usually the lower. Located at the frame end of the torsion bar is an adjuster or key. These are sometimes referred to as hex keys are used to apply the twisting motion needed for vehicle suspension and adjustment. The left and right sides are often different and not interchangeable.
There are several factors involved in adjusting the ride height of a vehicle with torsion bar suspension. The angle of the control arm and the amount of torque or twisting motion applied to the torsion bar. On some vehicles, the CV joints can wear prematurely if the ride height is over adjusted.
The dimensions (thickness) of the bar itself are essential. Vehicle manufacturers, as well as aftermarket companies, provide heavy-duty bars by increasing the thickness from 22mm to 24mm. A manufacturer may install a thicker bar for a bigger engine. They also use different materials to construct the bars depending upon the application.
Take measurements before and after adjustments are performed. A good spot would be between the lower part of the fender and the top of the wheel rim. Measure the distance from the base of the bolt head to its mating surface as a reference point. Tightening this bolt turns a key that twists the torsion bar. This extra torque applies more force to the control arm, raising the vehicle to the desired height. Always check for special procedures on the vehicle your adjusting.