Theres been a LOT of threads in regards to torsion bars lately. Crank them, uncrank them.. What I feel is lacking is a basic understanding of what happens to the suspension geometry when either is done.
Contrare to popular belief, Your front wheels do NOT travel in a perfectly vertical direction. They travel in an Arc..
When something effects one of the control arms, Laws of physics and trig show there is an effect on the upper arm. If one stays constant, the other must as well. For every action to one, there is an equal reaction to the other.
When the lower arm is forced downward, the upper will move downward as well. The opposite also happens, when the lower is forced upwards, the upper moves in the same direction as well. The Upper arm has a constant value. Its not going to shorten nor lengthen, thus when the torsion bars are cranked, the top of the tire will move outward. When the tension is let off the torsion bar, the top of the tire will move inward. The Axis of the upper arm is a constant. Eccentric's or ' Cams ' can be used on the upper arms to move the pivoting points but after being ' aligned ' or ' adjusted ', they become constant once more.
So long as both arms are the same weight, with the exact same balljoint location, the wheel WOULD travel vertically. Such is not the case with Ranger Trucks on Torsion bars. The Upper Balljoints sit a full inch and a half inside the vertical position of the lower arms. The offset is provided by the deflection angle of the spindles themselves for tire clearance.
If you look at the top of the spindle in this pic..
.. Its clearly seen how the spindle joggs inward in its design.
The lower control arms are MUCH longer from their pivoting point then the uppers ( roughly 5.25 inches SAE ).
If the arms were completely Parallel to one another on a horizontal plane, they COULD have a straight vertical travel. Unfortunatly, this isn;t how they were built.
Theres many angles to the front suspension. If ONE is effected, they all are..
Even though this picture depicts body roll, it also shows the suspension as to where its ' moving parts ' are located/effected.
Lets apply math here.. in this picture..
The torsion bars are used to change the vector angle of the lower control arm. This will change the geometry/angle of point ' c' . ' Lifting ' the front end makes angle ' c ' smaller, lowering makes it bigger. BOTH have an effect/impact on the surface area of your tire, its contact patch, and can cause unever wear OR pre-mature failures of other suspension components.
Torsion bars have a rating that is calculated into the geometry of the suspensions design. Weight of the vehicle and tire size have a mathematical value. Tire rubbing, turning radius and other factors are also tossed in to the equation.
ANY changes made to the torsion bar be it tightening, loosening or changing bars themselves should be followed by an alignment to put the geometry back into proper functioning fashion.
Hope this helps.