Ackermann, in the context of vehicle dynamics, refers to the Ackermann steering geometry, a design that ensures the inner and outer wheels turn at the appropriate angles during a turn. This geometry causes the inner wheel to turn at a sharper angle than the outer wheel, allowing for more efficient and precise cornering. The concept minimizes tire slip and wear during turns, as it ensures that all wheels follow their natural paths along concentric circles, improving handling and stability.

Anti-dive refers to a design characteristic that reduces the front end's tendency to lower during braking. This is achieved by adjusting the suspension geometry so that the forces generated under braking create a counteracting torque, which minimizes the suspension's compression. Anti-dive is designed into the car's suspension geometry to control how the weight transfers to the front wheels under braking, helping to maintain stable handling and better control.

Anti-lift in cars refers to a suspension design feature that minimizes the tendency of the front end to lift during acceleration. By adjusting the suspension geometry, anti-lift counteracts the upward force generated when accelerating, helping to keep the front wheels more firmly planted on the road. This improves traction, handling, and stability by ensuring more consistent contact with the road surface, especially under hard acceleration.

Anti-squat in cars is a design feature in the suspension system that reduces the tendency of the rear end to squat or lower under acceleration. This is achieved by configuring the suspension geometry in a way that the forces generated during acceleration create a counteracting torque, minimizing the compression of the rear suspension. This helps maintain better traction and stability by distributing the vehicle's weight more evenly across all wheels during acceleration

An anti-roll bar, also known as a sway bar or stabilizer bar, is a component of a car's suspension system designed to reduce body roll during sharp turns or irregularities in the road. It connects opposite wheels together through short lever arms linked by a torsion spring, helping to maintain balance and stability by distributing the force of the turn evenly across the vehicle, which reduces the leaning effect and improves handling.

Balance in terms of a car's handling refers to how evenly the forces are distributed across the vehicle when it is in motion, particularly during turning, accelerating, and braking. A well-balanced car will evenly distribute weight between the front and rear wheels, and left to right, providing stable and predictable handling. This balance helps ensure that the car responds effectively to steering inputs, maintains good traction, and avoids excessive oversteer (where the rear end swings out) or understeer (where the front of the car continues straight despite turning the steering wheel). Achieving optimal balance in a car's handling involves tuning the suspension, weight distribution, and geometry to create a harmonious interaction between the vehicle and the road.

A ball joint is a pivot point used in the suspension system of a vehicle, allowing the steering knuckles and control arms to move freely in three dimensions. It consists of a ball and socket that provides a flexible connection, facilitating smooth steering and suspension movement. Ball joints are crucial for maintaining precise control of the wheel and suspension alignment, enabling the wheels to respond correctly to steering inputs and road conditions. They wear over time and may require replacement to ensure the vehicle's proper handling and safety.

Bar rate refers to the stiffness or spring rate of an anti-roll (sway) bar, which is a measure of how much force is required to twist the bar a certain angle. This is measured either at the drop links or the wheel's contact patch. It is an indicator of how resistant the bar is to bending when lateral (sideways) forces are applied to the vehicle during cornering. A higher bar rate means a stiffer bar, which reduces body roll and improves the vehicle's handling and stability in turns. Conversely, a lower bar rate indicates a more flexible bar, allowing more body roll and potentially offering a smoother ride. The bar rate is an essential aspect of tuning a vehicle's suspension for desired handling characteristics.

Bleed refers to the controlled release of hydraulic fluid through small openings in the damping system, allowing a consistent flow even under low-speed suspension movements. This helps in achieving a smoother response of the suspension system to minor road irregularities, enhancing ride comfort and handling stability by preventing the suspension from being too stiff or unresponsive during slow, subtle movements.

Body roll in vehicles refers to the lateral tilting or leaning of the car's body that occurs during cornering, turning, or rapid changes in direction. It is caused by the centrifugal force acting on the vehicle's center of gravity, which shifts the weight to the outside of the turn, leading to a tilt in the chassis. Excessive body roll can affect the vehicle's handling and tire grip on the road. Suspension components like anti-roll bars, stiffer springs, and dampers are used to control and minimize body roll, improving the stability and handling of the vehicle.

bounce refers to the vertical up-and-down movement of a car's body as it reacts to uneven road surfaces or disturbances. It is a result of the suspension system compressing and rebounding to absorb shocks. Properly functioning suspension will minimize this bouncing motion, ensuring that the tires maintain consistent contact with the road for better traction, handling, and comfort. Excessive bounce can indicate issues with the suspension components, such as worn shock absorbers or springs, necessitating inspection and potential repairs.

Bump refers to a change in toe angle during suspension travel.

refers to the distance or range of movement that the suspension can compress or move upward when the wheel encounters a bump or obstacle. It is the upward movement of the wheel and suspension components from their normal resting position to the point where they are fully compressed.

A bump-stop is a component in a vehicle's suspension system designed to limit the maximum compression of the suspension to prevent damage. It acts as a cushion, usually made of rubber or foam, positioned to come into contact with the suspension or chassis before it bottoms out. Bump-stops help absorb and dissipate the energy generated during hard impacts, such as when driving over large bumps or potholes, and protect the suspension components from excessive force and potential damage. They contribute to maintaining the vehicle's handling characteristics and ride comfort by preventing the suspension from compressing beyond its designed limits.

is a type of vibration isolator that provides a cushioning effect between the car's suspension parts. It is typically made of rubber or synthetic materials and is used to reduce friction and wear between metal parts, absorb shock, and minimize noise and vibration. Bushings are found in various parts of the suspension system, such as control arms, stabilizer bars, and shock absorbers, helping to ensure smooth and stable vehicle handling by allowing limited movement while maintaining alignment of the components.

Camber is the angle of the wheels in relation to the vertical axis of the vehicle when viewed from the front or rear. If the top of the wheel leans out from the center of the car, it's called positive camber; if it leans in, it's negative camber. Camber affects the tire contact patch with the road, influencing grip, handling, and tire wear. Proper camber settings can improve cornering performance by optimizing the tire's contact area during turns.

Camber thrust refers to the lateral force generated by a wheel with camber angle (tilt of the wheel relative to the vertical axis) when it is rolling. This force occurs because the contact patch of the tire generates a sideways force as the tire rolls at an angle. In a turn, a tire with positive camber (top of the wheel tilting away from the vehicle) or negative camber (top of the wheel tilting towards the vehicle) will produce camber thrust that can affect the vehicle's handling. Negative camber, common in performance driving, helps to increase grip during cornering by maximizing the tire's contact patch with the road, thus generating more camber thrust and improving cornering performance.

Caster is the angle created by the steering pivot point from the front to the back of the vehicle when viewed from the side. For Double A-Arm this is measured through the ball joints of the upper and lower arm.

In MacPherson strut it is measured through the centreline of the strut.

Positive caster is when the top of the steering axis is tilted towards the rear of the car, which helps with stability and steering returnability. Negative caster is less common and would tilt towards the front. Caster influences the steering effort, stability at high speeds, and cornering effectiveness of the vehicle.

The centre of gravity in cars is the point where the car's total weight is considered to be concentrated and where it is balanced in all directions. It affects the car's stability and handling; a lower centre of gravity typically leads to better stability and cornering performance because it reduces the vehicle's tendency to roll or tip over during turns.

Coil bind is the point where the spring is compressed and the coils are making contact. The spring is no longer able to compress any further

A coilover is a type of suspension device that combines a shock absorber and a coil spring into a single compact unit. The coil spring encircles the shock absorber, effectively integrating the two components. This setup allows for adjustments in ride height, spring preload, and sometimes damping characteristics, providing a customizable balance between performance, comfort, and vehicle stance. Coilovers are popular in performance and racing vehicles because they offer improved handling, reduced body roll, and a lower center of gravity.

A coil spring is a type of mechanical spring made of an elastic material, usually steel, wound into a helical shape.

compression refers to the action or process where the suspension system absorbs impact from the road by allowing the wheels and springs to move upwards towards the body of the vehicle. This movement compresses the suspension springs and dampers, helping to cushion the ride and maintain tire contact with the road surface. Compression occurs when a vehicle encounters bumps, potholes, or other irregularities, and the suspension system works to minimize the impact felt inside the vehicle and maintain stability and control.

A damper, also known as a shock absorber, is a key component in a vehicle's suspension system designed to control and dissipate the energy of the springs' oscillations. Dampers reduce the bounce and vibrations by converting the kinetic energy from the suspension movement into thermal energy (heat), which is then dissipated through hydraulic fluid. This process helps to stabilize the vehicle, reduce the rate of bounce, and improve handling and comfort by controlling the movement of the suspension and maintaining consistent contact between the tires and the road surface.

Damping force in the context of vehicle suspension refers to the force exerted by the dampers or shock absorbers to control the motion of the suspension and vehicle body. This force is generated as the damper converts the kinetic energy of the moving parts into thermal energy, which is then dissipated as heat. Damping force is critical for reducing the amplitude of oscillations and vibrations of the vehicle's suspension system, thereby providing a smoother ride and improved handling. It acts to slow down the suspension's compression and rebound movements, helping to maintain tire contact with the road and control body movement during driving maneuvers.

refers to the movement or displacement of suspension components under load. It is the distance that a part of the suspension system, such as a spring, arm, or wheel, moves from its rest position in response to forces such as bumps, potholes, or cornering.

refers to the extent to which the suspension can extend when a wheel is not supporting the weight of the vehicle, such as when it is lifted off the ground or during uneven road conditions. It is the downward movement or extension of the suspension components from their normal position, allowing the wheel to maintain contact with the road as much as possible.

Heave, in vehicle dynamics, refers to the vertical movement or displacement of a vehicle's body or chassis, typically measured at the center of gravity. It represents the upward or downward motion of the vehicle in response to various forces and inputs, such as road irregularities, acceleration, braking, or changes in load.

A helper spring is a small, secondary spring used in conjunction with the main suspension spring, typically in performance or racing vehicles with coilover suspensions. Its primary purpose is to keep the main spring under tension when the suspension is fully extended, or in droop, preventing the main spring from becoming unseated or loose. Helper springs are much softer and have a lower spring rate compared to the main spring, allowing them to compress easily and only come into play when the suspension is fully extended, ensuring that the main spring remains in the correct position throughout the full range of suspension movement.

a hub is the central part of a wheel to which the spokes or rim attach. It is mounted on the axle and serves as the pivot point around which the wheel rotates. The hub contains bearings that allow the wheel to spin smoothly on the axle with minimal friction. It also typically has a flange with studs or bolt holes for securing the wheel to the vehicle. The hub is a crucial component in the wheel assembly, providing the structural support for the wheel and facilitating its rotation for vehicle movement.

The included angle in vehicle suspension and steering geometry is the total angle formed by combining the camber angle and the steering axis inclination (SAI/KPI). It is the angle between the vertical line (when viewed from the front of the vehicle) and the line through the center of the suspension's upper and lower pivot points. The included angle is important for diagnosing suspension issues, as it helps in understanding the alignment and steering characteristics of the vehicle. Changes or discrepancies in the included angle can indicate problems like bent or misaligned suspension components.

Jacking forces refer to the vertical forces exerted on a vehicle's suspension and body when it corners, causing the body to lift or "jack up" on the side opposite to the direction of the turn. These forces are a result of the lateral acceleration during cornering, interacting with the suspension geometry, particularly with elements like the height of the roll center. Jacking forces can affect the vehicle's handling, potentially leading to instability, as they alter the vertical load distribution between the wheels and can cause one side of the vehicle to rise, reducing tire contact and grip on the road surface. Managing these forces through suspension design is crucial for maintaining balance and stability during cornering.

In automotive terms, KPI stands for Kingpin Inclination, also known as the steering axis inclination (SAI). It is the angle between the vertical line and the centerline of the kingpin or steering axis when viewed from the front of the vehicle. The KPI angle is crucial for steering dynamics as it helps to stabilize the vehicle in a straight line and contributes to the self-centering characteristic of the steering. It affects how the vehicle handles and the effort required to steer the vehicle. A properly set KPI can reduce tire wear and improve vehicle handling by optimizing the contact patch of the tire during turning and driving.

The instant centre, also known as the instantaneous center of rotation, in automotive suspension terms, refers to the theoretical point around which a particular wheel assembly pivots at any given moment. It is determined by extending imaginary lines through the suspension arms or links to the point where they intersect. For a vehicle in motion, the instant centre changes position as the suspension moves through its range of travel.

Motion ratio in the context of vehicle suspension is the ratio of the movement of the wheel to the movement of the suspension component, usually the spring and damper. It describes how effectively the wheel movement is translated into the suspension system. A motion ratio close to 1 means that the wheel and the suspension travel nearly the same distance, while a lower ratio indicates that the suspension travels less distance compared to the wheel.

Pitching in automotive terms refers to the rotational movement of a vehicle around its lateral axis, which extends from side to side. This motion causes the front and rear of the vehicle to move up and down opposite each other, similar to a seesaw effect. Pitching occurs during acceleration (nose lifting) and braking (nose diving), as well as when driving over uneven road surfaces.

refers to the initial tension applied to the suspension springs before the vehicle is subjected to any weight. It is the amount of compression that a spring is under when the suspension is fully extended.

Rebound in the context of vehicle suspension refers to the extension or return movement of the suspension after it has been compressed. It occurs when the suspension springs and dampers expand back to their normal position after absorbing the impact from road irregularities or bumps. Rebound controls the rate at which the suspension returns after being compressed, helping to maintain tire contact with the road and ensuring stable and controlled handling.

The roll axis in a vehicle is an imaginary line that runs from the front to the rear of the vehicle, passing through the centers of the front and rear suspension roll centers. It represents the axis around which the vehicle's body rolls or tilts during cornering or when lateral forces are applied. The angle and height of the roll axis relative to the ground influence the vehicle's handling characteristics, particularly its susceptibility to body roll.

the rate at which a vehicle's body or chassis rolls or tilts during cornering or lateral maneuvers. It is a measure of how quickly the vehicle's weight shifts from one side to the other as lateral forces are applied, such as when turning or negotiating curves.

A higher roll rate indicates that the vehicle's body rolls more quickly in response to lateral forces, while a lower roll rate means that the body rolls more slowly. Roll rate is influenced by various factors, including the vehicle's suspension geometry, stiffness of the springs and anti-roll bars, weight distribution, and tire characteristics.

The scrub radius is the distance between the projected point where the steering axis intersects the ground and the center of the tire's contact patch with the road surface. It represents the lateral offset between the two points and is influenced by factors such as wheel offset, tire width, and steering geometry.

A positive scrub radius occurs when the steering axis intersects the ground outside the tire's contact patch, meaning the tire contact patch is closer to the vehicle's centerline than the steering axis point. A negative scrub radius occurs when the steering axis intersects the ground inside the tire's contact patch, with the tire's contact patch being farther from the vehicle's centerline than the steering axis point.

Self-aligning torque, also known as aligning torque or aligning moment, is a term used in vehicle dynamics to describe the force that helps a tire return to its straight-ahead position after being steered off-center. When a tire is turned away from its straight-ahead position, it generates lateral forces due to its slip angle. These lateral forces create a self-aligning torque that acts to steer the tire back towards its original direction of travel.

Is the angle between the direction in which a tire is pointing (the direction it is steered) and the direction in which it is actually moving (the direction of travel). It is a measure of the deviation between the intended steering angle and the actual path of the vehicle.

When a vehicle is cornering, the tires experience slip angles as they deform and generate lateral forces. A positive slip angle occurs when the tire is turned more than its direction of travel, while a negative slip angle occurs when the tire is turned less than its direction of travel.

Sprung weight refers to the portion of a vehicle's total weight that is supported by the suspension system. This includes the weight of the vehicle's body, chassis, passengers, cargo, and any other components directly supported by the suspension. The term "sprung weight" is used to differentiate it from the unsprung weight, which includes the weight of the wheels, tires, brake assemblies, and other components not directly supported by the suspension.

Stiction refers to the static friction or resistance encountered when trying to move an object from a resting or stationary position. It is a combination of the words "static" and "friction" and represents the force required to overcome the initial resistance and start the object's motion.

In the context of mechanical systems such as automotive components, stiction can occur in various moving parts, including suspension components, bearings, seals, and actuators. It is particularly noticeable in systems where there is limited movement or where components have been stationary for extended periods.

Stiction can affect the performance and operation of mechanical systems by causing delays, jerky movements, or inconsistencies in motion. It can also lead to wear and damage over time if not properly addressed.

Thrust angle refers to the angle between the centerline of a vehicle's rear axle and a line perpendicular to the vehicle's longitudinal axis. It is a measure of how the rear wheels are aligned in relation to the vehicle's overall direction of travel.

A tie rod is a crucial component of a vehicle's steering system that helps transmit steering input from the steering gear or rack to the wheels. It is a rod-shaped linkage that connects the steering knuckle or spindle to the steering rack or center link, depending on the vehicle's configuration.

The angle at which the wheels are pointed relative to the centerline of the vehicle when viewed from above.