The four-wheel alignment of a vehicle mainly adjusts the relative positional relationship between the wheels and the chassis (wheels, knuckles, front axles, etc.). The positioning of the front wheels includes four items: kingpin rear tilt, kingpin inward tilt, and front Wheel camber and front wheel toe; for the rear wheels, there are two items: rear wheel camber and rear wheel toe. (Due to the limited space, we will not do a more detailed interpretation of four-wheel positioning here)
However, with the development of the times, as far as current vehicles are concerned, the four-wheel-aligned front wheels can basically only adjust the toe of the front wheels, and the caster, kingpin inclination and front wheel camber are basically set by the factory. Fixed and cannot be adjusted later.
Looking back, even if the vehicle needs to remove the entire connection between the front suspension and the wheel hub when replacing the shock absorber, the length of the steering tie rod that affects the toe of the front wheels has not changed. When the shock absorber is replaced and the steering horizontal and straight tie rod is installed, its relative position will return to its original state. Therefore, there is no need to do four-wheel alignment after the vehicle has replaced the shock absorber.