Torsion Bar Adjustment
Torsion bars are used on the suspensions of both cars and trucks to 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 will alter the vehicles ride height effecting stability and 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 and are used to apply the twisting motion needed for vehicle suspension and adjustment. The left and right side are often different and not interchangeable.
There are several factors involved in adjusting the ride height on a vehicle with torsion bars. The amount of torque or twisting motion applied to the torsion bar by turning the adjustment bolt. The angle of the control arm is important. If the ride height is over adjusted the CV joints will wear prematurely. The dimensions (thickness) of the bar itself is important. Vehicle manufacturers as well as aftermarket companies provide heavy duty bars by changing the thickness from 22mm to 24mm etc. A manufacturer may install a thicker bar for a bigger heavier engine. They also use different materials to construct the bars depending upon the application.
Adjusting a torsion bar is usually pretty straight forward. Always 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 bolts head to its mating surface as a reference point. Tightening this bolt will turn the key which will twist the torsion bar. This extra torque will apply more force to the control arm raising the vehicle to the desired height. Over adjustment will cause a harsh ride. Backing this bolt off will lower the suspension. Always check for special procedures on different vehicles.
The more tightening adjustment that is applied to a torsion bar the firmer the ride. Always test drive the vehicle to make sure everything seats correctly and then recheck the measurements. Worn torsion bar pivot bushings and control arm bushings will cause a rough ride or a squeaking noise while driving. Sometimes a little silicone based lubricant will do the job. Other times they need to be replaced. Check for TSB's. Check the vehicles wheel alignment as well. Changing a vehicles ride height will effect several different steering angles.
