Steering Axis Inclination

Steering axis inclination is the inward tilt of the steering knuckle. It is so interrelated with the camber that they share a common side (vertical axis of the wheel). With the steering axis tilted inward (inclined), the end of the spindle will form an arc that is lower in the extreme turn position than in the center or straight ahead position. In normal operation, the weight of the car prevents the spindle from moving up and down. Therefore, the car is forced upward when the front wheels are turned, and the force of gravity tends to straighten the wheels. In this way, the weight of the car helps to provide an automatic steering effect brought about by accurate adjustment of the steering angles. The combination of the camber tilt and the steering axis inclination forms an important junction that is known as the "included angle." The purpose of this two-angle team is to place the turning point of the wheel at the center of the tire tread contact area to reduce the scuff area to a minimum. The benefits of additional alignment becomes apparent when some of the troubles caused by misalignment are seen; these include: hard steering, wander, pull to one side, and unequal or excessive tire wear.