Wheel Alignment

Wheel AlignmentWheel alignment refers to the proper setting of the axle geometry as well as tracking of all axles on a vehicle. The purpose of the alignment is to:

  • Minimize tyre wear
  • Maximize predictable handling and driver control.
  • Overall safer vehicle operation.

Have your alignment checked periodically as specified by vehicle manufacturer manual or whenever there is a indication of trouble such as uneven wear in tyres, pulling, vibrations etc.

It is also recommended that tyre wheel assembly should be checked for proper balancing.

Major Vehicle Alignment Factors That Affect Tire Life:

  • Toe Settings:  First and foremost
  • Rear Axle Alignment Geometry:  2nd
  • Camber:  3rd

 

Factor #1

Toe Settings

  • The purpose of toe is to allow the tire to run straight during normal operating conditions
  • Deviation from this condition results in either:
  • toe-in or positive toe
  • toe-out or negative toe
Toe In / Positive ToeToe In/Positive Toe
Positive toe is necessary for improved tread life
Toe-Out / Negative Toe
Toe-Out/Negative Toe
Negative Toe accelerates tread wear

Factor #2

Rear Axle Alignment

Rear Axle Alignment

  • Affects vehicle tracking
  • Terms utilized in rear axle alignments:
    • Parallelism = Scrub = skew = tram
    • Thrust angle = square

 

Parallelism

Parallelism, Scrub, Skew or Tram

  • Parallelism, scrub, skews or tram is referenced by the angle formed by two lines projected through the length of the axle. This angle is sometimes simplified into a measurement between the difference in axle spacing on opposite sides of the vehicle.
  • Angle measured between two rear axles

 

Tandem Scrub AngleEffects of Parallelism, Scrub, Skew or Tram:

  • Causes ALL axles to work against each other
  • Requires steer axle to be turned to compensate for the “push” of the rear axles to keep the vehicle moving in a straight path

Factor #3

Camber

  • Camber is the inward or outward tilt of the top of the tires when viewed from the front of the vehicle
  • Labeled as either positive or negative

Positive Camber
Positive Camber

Negative Camber
Negative Camber

Wear Characteristics Due To Excessive Camber:

  • Excessive positive camber:
    • smooth wear patterns on the outer half of the tire tread
  • Excessive negative camber:
    • smooth wear patterns on the inner half of the tire tread

Wheels

 

  • The state of all wheels should be regularly checked. Any cracked wheel or rim should be replaced.
  • Wheels or rims should not be repaired by welding. If a welding operation has to be undertaken, the tyre must be removed from the rim. If this is not done, there is a serious risk of explosion.
  • The tyre should only be refitted when all items have returned to ambient temperature.
  • Before any welding on the vehicle chassis or at proximity of the tyres, the tyre and wheel assemblies should be removed from the vehicle.
  • Before removing divided wheel assemblies from a vehicle, it is recommended that the tyres are deflated