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4WD SUSPENSION
Page 6 of 7
Torsion Bars
Torsion bars are straight lengths of steel round bar with splines at each end connected to the front wishbone and the chassis. As their name suggests, they use the torsional (twisting motion) resistance of steel to counteract the weight of the vehicle.
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GOOD POINTS
Newton’s first law of physics says that for every action there is an equal and opposite reaction. This means that when the weight of a 4WD is placed on its springs, its springs will exert a force equal to the weight of the vehicle back into the chassis wherever they are mounted. Many 4WDs weigh over 2t, and that means strong spring mounting points are needed on the chassis.
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Because a torsion bar applies the spring load into the chassis below the front floor, it saves the need for bulky spring mounts under the wheel arches, leaving more room for shock absorbers and linkages. This means less stress is placed on the front chassis rails, leaving them free to support the engine. Gaining a little extra ride height with torsion bars is simple. Just wind up the bolt supporting the rear spline of the bar, and the car will sit higher off the ground. Simply increasing the ride height of a 4WD doesn’t increase overall wheel travel. It increases upward wheel travel and decreases downward wheel travel. BAD POINTS Stronger torsion bars are available for many 4WDs for those wishing to beef up their front end, but there is a limit as to how much stiffer you can make a torsion bar. Increasing the diameter of the bar increases the stiffness, but the diameter of the bar can’t exceed the diameter at the splines. |
