Alignment should only be performed after it has been verified that all parts of the steering and suspension systems are in good operating condition. The truck must be empty. The tires must be cold and inflated to the correct pressure and the test surface must be level and horizontal.
Because special, elaborate equipment is required for proper front end alignment, it is recommended that the truck be taken to a reputable alignment shop.
See Figure 1
Caster is the forward or rearward tilt of the upper ball joint, which results in a slight tilt of the steering axis forward or backward. Rearward tilt is referred to as positive caster, while forward tilt is referred to as negative caster.
Caster is adjusted by creating a difference in the total number (thickness) of shims, front and rear, between the upper control arm pivot shaft and its mounting bracket. Adjustment requires the use of special equipment.
See Figure 2
Camber is the inward or outward tilt from the vertical, measured in degrees, of the front wheels at the top. An outward tilt gives the wheel positive camber. Proper camber is critical to assure even tire wear.
Camber is adjusted by adding or subtracting the same number and thickness of shims at the front and rear upper arm pivot shaft attaching bolts. Adjustment requires the use of special equipment.
See Figure 3
Toe is the amount measured in a fraction of an inch, that the front wheels are closer together at one end than the other. Toe-in means that the front wheels are closer together at the front of the tire than at the rear; toe-out means that the rear of the tires are closer together than the front.