Body roll is the axial rotation of a vehicle’s

body Body may refer to: In science * Physical body, an object in physics that represents a large amount, has mass or takes up space * Body (biology), the physical material of an organism * Body plan, the physical features shared by a group of anima ...

towards the outside of a turn. Body roll occurs because the compliance in

vehicle suspension Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/ handling and ride ...

allows the vehicle body, which sits upon the suspension, to lean in the direction of the perceived

centrifugal force In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is paralle ...

acting upon the vehicle.

Cause

Vehicle suspension allows a vehicle’s

wheels A wheel is a circular component that is intended to rotate on an axle bearing. The wheel is one of the key components of the wheel and axle which is one of the six simple machines. Wheels, in conjunction with axles, allow heavy objects to be ...

to move independently of its body. This smooths the ride for occupants and cargo while allowing the wheels to stay in contact with the ground over bumps. In a corner, the

range of motion Range of motion (or ROM), is the linear or angular distance that a moving object may normally travel while properly attached to another. It is also called range of travel (or ROT), particularly when talking about mechanical devices and in mechanic ...

in the suspension allows the vehicle body to lean over toward the outside of the turn as the body tries to continue in a line

tangential In geometry, the tangent line (or simply tangent) to a plane curve at a given point is the straight line that "just touches" the curve at that point. Leibniz defined it as the line through a pair of infinitely close points on the curve. More ...

to the corner. Softer suspension with more travel will allow more body roll than harder suspension with less travel.

Adverse effects

Body roll allows a vehicle’s

centre of mass In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may ...

to move towards the outside of the turn, increasing the

load transfer Weight transfer and load transfer are two expressions used somewhat confusingly to describe two distinct effects: *the change in load borne by different wheels of even perfectly rigid vehicles during acceleration *the change in center of mas ...

to the outside wheels. This can cause

understeer Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occu ...

oversteer Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occu ...

to occur more easily than if body roll was not a factor. Body roll can also be uncomfortable for passengers and cause damage to cargo.

Mitigation

Anti-roll bars An anti-roll bar (roll bar, anti-sway bar, sway bar, stabilizer bar) is a part of many automobile suspensions that helps reduce the body roll of a vehicle during fast cornering or over road irregularities. It connects opposite (left/right) wheels ...

are suspension components designed to mitigate body roll. They do this by connecting the wheels at either end of an

axle An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing ...

with a torsion bar attached to the vehicle body. Body roll can also be reduced by lowering centre of mass of the vehicle body, fitting stiffer suspension springs and reducing the

sprung mass Sprung mass (or sprung weight), in a vehicle with a suspension, such as an automobile, motorcycle, or a tank, is the portion of the vehicle's total mass that is supported by the suspension, including in most applications approximately half of the ...

of the vehicle.

References

{{AutomotiveHandlingNav Automotive suspension technologies