Front Axle
Maintaining the front axle alignment to specifications is very important. A qualified technician should check and maintain the alignment.
Regular inspections should include:
- Toe-in inspection and adjustment (if necessary), particularly with radial tires.
- Checking for proper tightness of axle mounting U-bolt nuts, attaching or mounting bolts and nuts.
- Checking the axle for damage, binding, worn parts and adequate lubrication.
- Checking the kingpins for excessive wear. Also, perform this check during other scheduled maintenance, for example as tire rotation or service, wheel bearing service and alignment. See the workshop manual for proper procedures.
Toe-in
It is essential to maintain correct toe-in and tire pressure for optimum tire wear.
Inspecting steer axle tires in the first
3,000–10,000 mi (5,000–16,000 km) generally shows if tires are wearing normally.
Rapid outside shoulder wear on both tires indicates too much toe-in.
Rapid inside shoulder wear on both tires indicates too much toe-out.
In P&D-type service, there can be a left-to-right steer tire tread life differential up to 40% depending on routes and other variables.
Follow the tire manufacturer's recommended cold inflation pressure for the tire size, load range (ply rating) and steer axle loading typical for their operation (each steer axle tire equals ½ steer axle loading).
Special applications may warrant a setting based on experience with the type of tire operating loads and conditions. Radial tires are more sensitive to toe-in setting than bias ply tires. Fine tuning school bus alignment to line-haul truck standards does not drastically improve tire tread life.