When the wheels on a vehicle don’t all agree on which direction to travel, they fight each other, removing a little rubber with every revolution. Your customers will have tires that wear more quickly, compromised handling and stability, and lower fuel economy because it takes extra energy to erase tire tread.
The wheels on a vehicle get out of alignment from shock damage, which results in some degree of bending in suspension components and/or the frame, and from gradual wear of bushings, ball joints, kingpins, tie-rod ends – anywhere mating components move relative to each other and produce friction and wear.
Minor misalignment usually can be corrected by means of mechanical adjustments. Sometimes, however, components must be replaced to restore alignment. Any alignment procedure, therefore, should start with a thorough inspection of all steering and suspension components.
FRONT-END ALIGNMENT
Three major components of front-end alignment are caster, camber and toe. These values can be measured by a variety of means, from string, plum-bobs, protractors and measuring tapes, to sophisticated, computerized, laser-measurement devices offered by a variety of manufacturers.
A vehicle’s service manuals should provide proper specs for caster, camber and toe, and will tell you where and how to measure and make adjustments.
CASTER
Caster is the forward or backward tilt of the kingpin or support arm at the top of a wheel-suspension assembly, and it is measured in degrees. Forward tilt is called negative caster, and backward is positive.
From tire-wear and fuel-economy standpoints, caster is the least critical element of alignment. But it has a profound impact on vehicle stability and handling.
