The automotive torsion bar is an elongated spring used to hold up the vehicle's frame and dampen rough terrain. Torsion bars are used in cars or trucks where there is limited space for the vehicle's suspension. Normally, torsion bars are held to the frame and lower control arm with large, adjustable mounts.
Jack up the vehicle on the wheel to be adjusted, and set the frame rail onto a jack stand. This is to release the stress on the torsion bar so it can be adjusted easily.
Crawl underneath the vehicle and locate the torsion bar mount on the frame. There will be a bolt in the centre of the mount, pointing upward. This is the adjusting bolt, and it will accommodate a large-sized socket driver.
Adjust the torsion bar. Turning the adjustment bolt clockwise will tighten it, raising the amount of load that can be placed on the bar. This will raise the vehicle when it is taken off the jack stand. Turning it counterclockwise will lower the available spring rate and cause the car to sit lower. Turning it too far in either direction can cause problems, so follow the specific vehicle's manufacturer guidelines when making wide adjustments. Normally, only one full turn will be enough to give the desired result.
Lower the vehicle, and check the clearances of the frame to the ground. They should be the same for both sides. If they are not, then more adjustment will be necessary to the torsion bar adjustment bolts.
The torsion bar adjustment bolt can be turned without jacking the car up, but it will not turn easily.
Be careful when crawling underneath a vehicle. Do not remove the torsion bar without specialised equipment.