Introduction to Roll Centre
Roll Centre is a concept that is fundamental to understanding the behavior and response of a vehicle as it moves around a corner. The Roll Centre is a virtual point around which the car body or suspension system rolls or tilts during cornering, braking or other maneuvers. The Roll Centre has a significant effect on the feels and behaviors of the vehicle, and is a main factor in issues such as body roll, camber and tire stability.
The principle of the Roll Centre is simple. Imagine a vehicle moving around a corner. When it does, the car body or suspension components will tilt or roll in reaction to the turn. This is usually due to the vertical forces in the suspension system that resist the cornering forces. The Roll Centre is the point around which this one-dimensional rotation occurs. In other words, it is the pivoting point of rotation.
Roll Centre can also be looked at in terms of camber, which is the angle created by two intersecting lines. In a vehicle, camber is the angle between the body and the wheels when viewed from the front or the rear. Camber has a direct affect on vehicle handling and stability, as it affects the forces applied to the tires in relation to the road surface.
In order to understand Roll Centre, it’s also important to look at the geometry of the suspension system. The geometry of the suspension system determines the position of the Roll Centre relative to the vehicle. The Roll Centre is usually located in the middle of the suspension system. This means that the Roll Centre is located at the same point for the front and the rear suspension systems.
The Roll Centre is important for controlling body roll. When the Roll Centre is in a different position than the center of mechanical resistance, the load on the tires will be higher. This can cause the vehicle’s body to sway more, or create an uneven force on the tires. Conversely, when the Roll Centre is properly aligned, the body roll is minimal and the tires can better absorb forces from the road.
The Roll Centre is also important for camber control. A camber gain is the increase in camber of the wheels when the suspension travels through its range of motion. Camber gain affects issues such as tire stability and gives the vehicle more grip, but too much camber gain can be a problem. By properly adjusting the Roll Centre, camber gain can be reduced and tire stability improved.
In closing, the Roll Centre is a critical concept in the understanding and analysis of vehicle behavior. By understanding the geometry of the suspension system, and adjusting the Roll Centre to its optimal position, the performance of the vehicle can be improved and problems such as body roll and camber gain can be eliminated. With the proper knowledge and understanding of the Roll Centre, even novice vehicle tuners can make huge improvements to their vehicle’s performance.
