Alignment: Description and Operation

General Information And Definitions





Toe-difference angle
a Toe-difference angle
D Centre point of operating circle

The toe-difference angle is the angle adjustment of the inner cornering wheel relative to the outer cornering wheel when negotiating a curve. Steering is designed in such a way that angular position of wheels changes as steering lock progresses.

A correctly adjusted toe-difference angle produces equal values for left and right lock and consideration of factory tolerances.

Toe-difference angle provides information on corresponding operation of steering trapezoid for left or right steering lock from centre position.






Camber
Inclination of the wheel from perpendicular.






Toe
Reduction in distance of front of front wheels to rear of front wheels. Toe prevents wheels from running apart while driving and consequently wheel shimmy and grinding, excessive tire wear, excessive loads on steering linkage and joints as well as hard steering of vehicle. Measurement is performed in "straight-ahead mode"






Caster
Is the inclination of the kingpin ("kingpin" corresponds to line through center point of spring strut support bearing and control arm ball joint) in direction of travel, viewed from the side.

Thanks to caster, wheels are pulled and not pushed. In a similar manner to king-pin inclination, when driving in curves or around corners, returning forces are reproduced to help return wheels to straight-ahead position.






Geometrical axis 1
Bisecting line of an angle from total rear-wheel toe.
Front-wheel measurements are taken in reference to this axis.

Symmetrical axis 2
Centre line running through front and rear axles.






Wheel offset
Angle by which one front wheel is displaced more towards front or rear than the other front wheel.






King-pin offset/scrub radius
Is the distance from center of wheel contact face to intersection of line extended from kingpin axis ("kingpin" corresponds to line through center point of spring strut support bearing and control arm ball joint).

Scrub radius is influenced by camber, king-pin inclination and rim offset.