What is Four-Wheel Alignment?

[McIan]

Four-wheel alignment is based on the four-wheel parameters of the vehicle, adjusted to ensure good driving performance and certain reliability. The installation of the steering wheels, steering knuckles, and front axle of a car has a specific relative position, which is called steering wheel alignment, also known as front-wheel alignment. Front-wheel alignment includes four aspects: caster angle, kingpin inclination angle, camber angle, and toe-in. Rear-wheel alignment includes camber angle and individual rear-wheel toe-in. Collectively, this is referred to as four-wheel alignment. Its purpose is to maintain stable straight-line driving, facilitate easy steering, and reduce wear on tires and steering components during driving. Below are relevant details: Functions: Front-wheel alignment includes caster angle, kingpin inclination angle, camber angle, and toe-in. Rear-wheel alignment includes camber angle and individual rear-wheel toe-in. Together, front-wheel and rear-wheel alignment are called wheel alignment, commonly known as four-wheel alignment. The role of wheel alignment is to keep the car driving straight stably, make steering easier, and reduce wear on tires and steering components during driving. Caster Angle: Viewed from the side, the steering kingpin (the rotation center when the wheel turns) tilts backward, which is called the caster angle. After setting the caster angle, a distance is created between the contact point of the kingpin centerline and the ground projection point of the wheel center (called the caster trail, similar to the backward tilt of a bicycle's front fork). This positions the wheel's contact point at the rear end of the kingpin's extension line, pulling the wheel backward due to rolling resistance during driving, naturally aligning the wheel with the driving direction. A large caster angle improves straight-line driving performance but also increases the caster trail. An excessively large caster trail can make the steering wheel heavy and worsen the wheel's bouncing due to road disturbances.