Overview
 
Types
 
Angles
 
Adjustments
 
Alignment Parts
 
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Angles

Alignment Angles

Alignment angles must be in specification for proper tire life, steering wheel return, vehicle stability and improved suspension component life. These three angles are generally adjustable.
CAMBER (above)
Camber is the angle formed between vertical and the wheel centerline. The wheel tilted in towards the engine is negative, and tilted out is positive. Correct camber helps improve tire life, enhance stability and reduce stress on other suspension parts.
 
 
 		 CASTER (above)
Caster is a line drawn through the steering axis, compared to vertical. If the axis is tilted back at the top, the angle is positive, tilted forward is negative. Caster improves stability, steering wheel return and cornering.
TOE (IN OR OUT)
This is an angle, or linear measurement, formed by a line drawn through the horizontal center of each wheel relative to the center line of the vehicle. Toe can be read as individual, or the total of two wheels on the same axle. Proper toe will reduce scuff and improve tire life by reducing running toe to near zero.
(positive) (negative)

 
  

The following alignment angles should also be checked, but correction often requires parts replacement.
 

STEERING AXIS INCLINATION (SAI)
This is determined by a line drawn through the lower and upper steering pivots relative to vertical. Steering Axis inclination helps the wheels return to the straight-ahead position. It also increases stability, requiring less caster angle, and improves stability under braking conditions. Alignment equipment may vary in procedure on how to measure this angle. If the SAl reading is combined with the camber reading, the sum of the two angles equals the included angle.

 

TURNING RADIUS (right)
This is also referred to as "toe-out on turns" because this condition is purposely created in turns. The angle is determined by the steering arms relative to the lower steering pivot. When the vehicle is steered into a turn the steering arms cause the wheels to turn at different angles, creating a toe-out condition. If both wheels turned at the same angle, the outside wheel would scuff excessively because its turning radius is greater. Because turning radius is determined by the steering linkage and the lower steering pivot, these components should be inspected if the turning radius is incorrect.

  

  

 
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