Preliminary Checks

49X mm 33.04.002

    Important: When aligning the front axle, it is essential that the rear axle(s) be checked for correct alignment at the same time. Alignment of the rear axle(s) has a direct impact on how the vehicle tracks.

  1. Steering axle wheel assemblies should be balanced, especially for vehicles that travel at sustained speeds of more than 50 mph (80 km/h). Off-balance wheel assemblies cause vibrations that result in severely shortened life for tires, and steering suspension parts.
  2. Do not mix tires of different size, type, or weight. Tire wear should be even and not worn to limits exceeding government specifications. Refer to  in this manual and  in the Western Star 47X and 49X Workshop Manual for more information. Replace any tire that is excessively worn.
  3. Check the inflation pressure of the tires. An underinflated tire causes tread wear completely around both tire shoulders. An overinflated tire causes tread wear in the center of the tire. See Fig..

    • Underinflation Wear

    • Overinflation Wear

    Fig. 1, Tire Damage Due to Underinflated or Overinflated Tires

  4. Check for out-of-round wheels and wheel stud holes. Replace the wheel if any of these conditions exist.
  5. On each side of the vehicle, check the height of the chassis above the ground. Sagging, fatigued, or broken suspension springs create a lopsided vehicle appearance. This causes an unbalanced weight distribution. Anything that changes the ratio of weight on the springs affects the alignment angles and also the tire tread contact area. Replace damaged springs as instructed in the applicable suspension section.
  6. On a vehicle equipped with a Freightliner AirLiner® rear suspension, check the ride height and make any necessary adjustments until it is within specification. See  in the Western Star 47X and 49X Workshop Manual for instructions.
  7. Inspect the front axle beam (also called the axle center) for bends or twists. If the axle beam is bent or twisted over 1/2 degree, replace it before aligning the front axle wheels.
  8. Check for damaged, worn, or bent steering gear or linkage parts. Make sure the steering gear is centered. Replace damaged components, and adjust the steering gear, using the instructions in the applicable steering section.
  9. Check the steering angle, and adjust the axle steering stops as needed. Refer to  in the Western Star 47X and 49X Workshop Manual.
  10. Check the tie-rod ends for correct adjustment, tightness, and damage. Refer to of this manual for instructions.
  11. Check the front wheel bearings for wear and incorrect adjustment.
  12. Perform a complete vehicle alignment check and compare the readings to those listed in Alignment Specifications in this manual.
Note:
Parent topic: All-Axle Alignment Check
Document Number: 0000119319
Manual Publication Date: 2024-05-16
Topic Publication Date: 2024-10-31