Proper alignment of the front wheels must be maintained in order to ensure ease of steering and satisfactory tire life.
The most important factors of front wheel alignment are wheel camber, axle caster, and wheel toe-in.
Wheel toe-in is the distance by which the wheels are closer together at the front than the rear.
Wheel camber is the amount the top of the wheels incline in or out from the vertical.
From axle caster is the amount in degrees that the top of the steering pivot pins are tilted toward the rear of the vehicle. Positive caster is inclination of the top of the pivot pin toward the rear of the vehicle.
These points should be checked at regulator intervals, particularly when the front axle has been subjected to a heavy impact. When checking wheel alignment, it is important that the wheel bearings and knuckle bearings be in proper adjustment. Loose bearings will affect instrument readings when checking the camber and toe-in.
If you start to notice abnormal tire wear patterns and handling characteristics (steering wheel is hard to return to the straight ahead position after negotiating a turn), then front end misalignment can be suspected. However, toe-in alignment maladjustment, rather than cast or camber, is more likely to be the cause of excessive or uneven tire wear on vehicles with twin I-beam front axles. Seldom is it necessary to correct caster or camber. Hard steering wheel return after turning a corner is, however, a characteristic of improper caster angle. Nevertheless, the toe-in alignment should be checked before the caster and camber angles after making the following checks:
- Check the air pressure in all the tires. Make sure that the pressures agree with those specified for the tires and vehicle model being checked.
- Raise the front of the vehicle off the ground. Grasp each front tire at the front and rear, and push the wheel inward and outward. If any free-play is noticed between the brake drum and the brake backing plate, adjust the wheel bearings.
There is supposed to be a very, very small amount of free-play present where the wheel bearings are concerned. Replace the bearing if they are worn or damaged.
- Check all steering linkage for wear or maladjustment. Adjust and/or replace all worn parts.
- Check the torque on the steering gear mounting bolts and tighten as necessary.
- Rotate each front wheel slowly, and observe the amount of lateral or side run-out. If the wheel run-out exceeds 1 / 8 in., replace the wheel or install the wheel on the rear.
- Inspect the radius arms to be sure that they are not bent or damaged. Inspect the bushings at the radius arm-to-axle attachment and radius arm-to-frame attachment points for wear or looseness. Repair or replace parts as required.