HOW CAMBER CHANGES Camber changes as the vehicle is loaded and as the suspension moves. Heavy loading typically makes wheel camber go negative while raising the suspension causes it to go positive. Many SLA suspensions are designed so camber goes positive, then negative as the suspension is raised. On vehicles with independent rear suspension, loading always causes a negative camber change at the rear wheels. Rear camber does not normally change on vehicles with solid rear axles regardless of loading.
The camber setting also changes when the wheels are steered to either side. The amount of change depends on the caster angle of the steering axis (See CAMBER ROLL in the section on CASTER).
CAMBER ALIGNMENT To compensate for normal camber changes that occur when a vehicle is loaded, many alignment specifications call for a slight amount of positive camber. Others, though, may specify zero camber or up to half a degree or more of negative camber. Always refer to the manufacturer specifications because static camber settings vary greatly from one vehicle to another. Most specifications allow a total range of about a degree in "acceptable" camber settings, but some allow more.
CROSS-CAMBER Camber readings on both sides should usually be within half a degree of each other. Too much of a difference (cross-camber) can create a steering pull because camber affects directional stability.
CAMBER MISALIGNMENT When camber is out of specifications, the vehicle may lead or pull to one side. A wheel that is perpendicular (perfectly vertical) to the road will roll straight ahead. But one that is tilted at an angle will follow a circular path. It's like leaning on a bicycle. The wheel becomes the end of an imaginary cone rather than a cylinder, causing the wheel to turn towards the direction it is leaning.
A wheel with positive camber will pull towards the outside while a wheel with negative camber will push towards the inside. The vehicle will lead or pull towards the side that has the most camber, or away from the side with the least camber. Camber is very sensitive to ride height, so ride height must be within specifications for camber to be correct. If camber is off on one side only, a close encounter with a pothole or curb may have bent a spindle, control arm or strut. A shift in the position of a strut tower can cause the same thing. A shift in the position of a cross member, on the other hand, will usually affect camber on both sides.
Measuring the steering axis inclination (SEE SAI), the "included angle" (the angle between SAI and camber), and camber can help you diagnose the underlying cause of the misalignment. SAI that's within specs and equal on both sides but an included angle and camber reading that's out of specs, for example, would tell you the suspension has a bent spindle or strut.