Wheel Alignment Wheel Alignment
A slight deviation from the zero-alignment position should enable the wheels of one axle to run smoothly without wobbling, to stabilise the straight running and keep the vehicle on track.
The alignment of an individual wheel marks the angle in which the wheel stands in relation to the longitudinal axis. If the wheel is parallel to this axis, then the alignment position is zero. If the alignment values of both wheels of one axle are added together, one arrives at the whole alignment value. If the front wheels roll towards each other it is positive (toe-in), if they roll away from each other, it is negative (toe-out). Previously, the front axle of front-wheel drive vehicles was adjusted to toe-out, the axle of rear-wheel drives, rather to toe-in. Todays vehicles, with very little play in the whole steering system, have only a minimal amount of either toe-in or toe-out. A small amount of toe-in often prevents slight wheel movements around the steering-swivel axis. With a rigid axle at the rear, the alignment value is always zero.
Unfortunately, the very simple method of aligning the wheels, (using a bar) by comparing the distance between the the front- and back edges of the wheel-rim, is not yet completely extinct. Perhaps it is still justified in the utility vehicle area, or as an emergency measure. The different measurement values from the conversion of the alignment shown in degrees, to the necessary millimeters, is interesting. This can be done using the formula for the radian measure by giving the wheel-rim diameter and the angle. Because of the front/rear comparative measurement, the radian measure must then be doubled. With 13- or 14-inch wheel-rims, approx. 10 minutes of angle represent one millimeter of difference. 02/09