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The cruiser comes into the shop with a front-end complaint: a shimmy, poor handling at high speed, or after jumping a curb or hitting a massive pothole, to check the front-end alignment. So exactly what is involved in an alignment? It is very different than the alignment on the police cars from the 1980s!
Alignment issues can involve vehicle safety, driver fatigue, fuel mileage, the service life of suspension components, vehicle ride, handling, and vibration, and tire mileage. Currently there are three types of alignment procedures:
First, the "old-fashioned frontend alignment," a process considered old technology. It may still be acceptable for the most basic procedure on a rear-wheel drive, solid rear axle car. And a few older shops still exist that offer a frontwheel alignment. However, with the newer, front-wheel drive, independent rear-suspension vehicles on the road, and with much tighter tolerances with today's vehicles, this type of alignment is virtually obsolete.
Second, the "thrust angle alignment." This allows the technician to confirm that all four wheels are "square" with one-another, i.e., the front wheels are aligned in conjunction with the rear wheels and that the rears are not offset, or "dog-tracking." The thrust angle alignment is acceptable with RWD vehicle with a solid rear axle, such as the Ford Crown Victoria Police Interceptor.
Third, the "four-wheel alignment." This type of alignment is a must for vehicles with four-wheel independent suspension, such as the Dodge Charger and Chevy Impala with adjustable rear suspensions. It doesn't matter if the car is FWD (Impala) or RWD (Charger). If it has an independent rear suspension, it needs a four-wheel alignment. The four-wheel alignment "squares" the front wheels with the rear wheels, and the rears are adjusted as needed.
Camber
Camber is how much the top of the tire tilts inward or outward with respect to the car. Looking at the vehicle from the front, the angle of the tire in relationship to the pavement is camber. If the top of the tire tilts inward toward the vehicle, this is negative camber. If the top of the tire tilts away from the vehicle, this is positive camber.
Camber adjustment affects both tire wear and handling. An aggressive driver may ask for more negative camber for better handling....