Ride control terms and definitions

Learn about some of the most common ride control terminology:

  • Active Suspension

    A suspension systems that uses a high pressure pump with hydraulic cylinders at each wheel to position the wheels with respect to the vehicle. Up and down motion of the wheels is actuated by electronically controlled valves.

  • Air Shock

    A type of overload shock absorber that can be inflated with air to increase the suspension's load carrying ability. (usually an aftermarket rather than an OEM system)

  • Air Spring

    Air-filled rubber or elastomer bags that are pressurized to provide support to the suspension. Air springs are used in place of conventional coil springs on some vehicles. Aftermarket air springs can be installed inside coil springs or between the axle and frame to provide additional lift support for handling overloads or towing.

  • Air Suspension

    A type of suspension that uses air springs instead of conventional steel springs. Computer operated vents on the air springs, suspension sensors and an onboard air compressor allow the system to maintain ride height and vary the suspension's ride characteristics.

  • All Wheel Drive (AWD)

    This drive system features four, full-time active drive wheels to reduce wheel slippage and provide greater driver control over the vehicle. AWD is operational at all times.

  • Bearing Plate

    A component of a front strut mount. Usually includes the steering pivot bearing along with a mounting plate.

  • Body Roll

    The leaning or tipping of a vehicle's body to one side when turning sharply. This reduces traction and increases tire scuff due to undesirable alignment changes. Body roll is controlled primarily by a sway bar, but the stiffness of the springs and shocks also play a role.

  • Bounce & Jounce Test

    A procedure used to observe how quickly or efficiently a vehicle suspension recovers after being pushed down aggressively. There is no OE specification, however it can provide some wear indications.

  • Bushing

    Usually a type of mounting insulator made of a rubber-type material. A bushing could also be a sleeve that separates components or be used as a simple bearing.

  • Cartridge

    As used in a serviceable suspension strut: The cartridge is a replaceable shock absorber insert.

  • Coilover Shock Absorber

    A shock absorber that includes a coil spring and an adjustable coil spring seat. The adjustment increases or decreases firmness and ride height.

  • Coil Spring

    A type of spring made of wound heavy-gauge steel wire used to support the weight of the vehicle. The spring may be located between the control arm and chassis, the axle and chassis, or around a MacPherson strut.

  • Compressed Length

    A measurement of total length when the shock or strut shaft is fully depressed into the unit's body. The measuring points are determined by the style of mountings. (see manufacturers information instructions)

  • Compression Stroke

    Also called Jounce: The shock or strut shaft traveling into/toward the body of the unit, like when hitting a bump.

  • Corner Unit

    (Module, Assembly) A ready to install or pre-assembled combination of a suspension strut, coil spring, mount, spring insulators and any required hardware.

  • Damper

    A generic name for any device (shock, strut, cartridge, stabilizer,etc.) who's primary function is to resist movement, control movement ocillations.

  • Damping (Damping force)

    The effect or amount of resistance to movement.

  • Electronic Stability Control (ESC)

    A computerized technology that improves the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, it automatically applies the brakes to help "steer" the vehicle where the driver intends to go. Braking is automatically applied to individual wheel, such as the outer front wheel to counter oversteer or the inner rear wheel to counter understeer. Some ESC systems also reduce engine power until control is regained. ESC does not improve a vehicle's cornering performance, it rather helps minimize the loss of control.

  • Extended Length

    A measurement of total length when the shock or strut shaft is fully extended. The measuring points are determined by the style of mountings. (see manufacturers information instructions)

  • Eye Rings

    A metal band that houses a mounting bushing. A shock or strut structural component.

  • Four Wheel Drive (4WD)

    In a Four Wheel Drive system, a secondary transmission assembly, called a transfer case, is driven from the main transmission. The transfer case distributes power to both axles to drive all four wheels. It is the heart of the Four-Wheel Drive system. Four-Wheel Drive can be full-time, in which power is delivered to both axles at all times or part-time, where the driver selects two or four wheel drive. Four wheel drive is often combined with independent suspension systems and off-road type tires to enhance driveability on rough, off-road terrain, or on-road driveability in unfavorable driving conditions.

  • Front Wheel Drive (FWD)

    A drive system where the engine and transaxle components apply the driving force to the front wheels rather than the rear wheels.

  • Gas Shock

    Any shock or strut that uses pressurized Nitrogen gas instead of oxygen: In a twin tube design, a low pressure Nitrogen gas is used to reduce aeration. The monotube design has a seperate high pressure Nitrogen gas chamber that reacts to driving conditions.

  • Jounce

    When you drive over a bump and the suspension is momentarily compressed, that's called jounce.

  • Independent Suspension

    A suspension system that allows each wheel on a vehicle to move up and down independently of the other wheels.

  • Leaf Spring

    A type of spring made out of a flat strip or individual leaves to support the weight of a vehicle. Most are steel, but some are made of lightweight composite materials.

  • MacPherson Strut

    A suspension system that consists of a combination coil spring and shock absorber (strut) in one compact unit at each wheel. With this "independent" suspension design, road shocks at one wheel are not transferred to the opposite wheel. MacPherson struts use fewer parts, meaning a reduction on weight and fewer elements that could wear out.

  • Mini-strut (spring seat shock)

    Sometimes called a spring seat shock: A shock absorber that includes a mounting area for a coil spring. Unlike a MacPherson suspension strut, this component does not eliminate an upper control arm.

  • Monotube

    A damping unit design that uses a single cylinder and incorporates a seperated high pressure gas chamber. In this design the gas does not mix with the hydraulic fluid. The gas area acts as the fluid expansion area and provides additional damping on demand. The fluid-only valve area provides more responsiveness compared to the twin tube design.

  • Mounting Hardware

    Nuts, bolts or other fasteners.

  • Mounting Stud

    A shaft with a threaded end. A mounting component.

  • Nivomat

    A trademarked type of shock absorber that controls ride height. (self-leveling) It contains a mechanical hydraulic pump activated by vehicle movement.

  • Non-serviceable Struts

    A sealed strut that does not have a replaceable cartridge. This unit must be replaced as an assembly.

  • Nose Dive

    Occurs during vehicle braking: The front of the vehicle surges downward and the rear of the vehicle surges upward.

  • Pinch Bolt

    A fastener (bolt) that secures,squeezes or prevents a component from turning.

  • Rear Wheel Drive (RWD)

    A drive system where the engine applies the driving force to the rear wheels only. This pushes the vehicle from the rear wheels

  • Rebound Stroke

    The motion of a wheel that extends the suspension. The opposite of jounce or compression stroke.

  • Ride Control

    Four separate vehicle systems (Tires, suspension, steering & brakes) that work together to control a vehicle's stopping, turning, handling, stability control and ride comfort.

  • Ride Height

    The amount of space between the base of an automobile tire and the underside of the chassis.

  • Self-leveling Shock

    A damping unit that automatically adjusts suspension balance and height to keep the vehicle level in all driving conditions.

  • Serviceable Strut

    A strut assembly that is designed with a replaceable cartridge. Some designs have an upper hex nut while others require a special cutting tool. See the vehicle manucaturers manual before attempting to disassemble.

  • Shock Absorber

    A device that converts motion into heat, usually by forcing oil through small internal passages in a tubular housing to dampen suspension oscillations.

  • Shock Fade

    A condition where loss of dampening action occurs because of fluid foaming inside a shock absorber. The rapid oscillations of the piston moving through the fluid churns it into foam, which reduces the amount of resistance encountered by the piston. This causes the dampening action to fade, resulting in loss of control, excessive suspension travel and reduced handling.

  • Shock Travel

    The measurable difference between the extended and compressed lengths of a shock or strut.

  • Spring Compressor

    A tool for compressing and holding a coil spring so it can be removed or replaced, or to allow the disassembly of a MacPherson strut.

  • Spring Seat (upper or lower)

    The mounting area for a suspension coil spring. This may be located on the vehicle or on the damping unit.

  • Spring Seat Insulator

    A cushion between a coil spring and spring seat that helps reduce noise and vibration.

  • Spring Seat Shocks

    Sometimes called a mini-strut: A shock absorber that includes a mounting area for a coil spring. Unlike a MacPherson suspension strut, this component does not eliminate an upper control arm.

  • Stability Control

    A type of advanced antilock brake/traction control system that uses the brakes to assist steering maneuvers and to help improve vehicle handling and stability as driving conditions change. The system includes various sensors that monitor the driver's steering inputs and the position of the body with respect to the road. A "yaw sensor" can tell if the vehicle is starting to understeer or oversteer in a turn. The stability control system is active fulltime and will apply individual brakes to create a counter-steer effect that brings the vehicle back under control.

  • Stalbilizer Link Pin

    The bolt, stud, bushings and washers used to attach a stabilizer (sway) bar to a suspension control arm.

  • Static Height Measurement

    A measurement taken when the shock or strut is installed on a vehicle (on level ground): From the lower measuring point to the upper measuring point.

  • Steering Damper (Stabilizer)

    A hydraulic device similar to a shock absorber attached to the steering linkage to absorb road shock and steering kickback.

  • Steering Knuckle

    A forging that usually includes the spindle and steering arm, and allows the front wheel to pivot. The knuckle is mounted between the upper and lower ball joints on a double wishbone (upper & lower control arms) suspension, and between the strut and lower ball joint on a MacPherson strut suspension.

  • Steering Stabilizer (Damper)

    A hydraulic device similar to a shock absorber attached to the steering linkage to absorb road shock and steering kickback.

  • Striker Plate

    An area at the top of a strut housing where the travel limiting bumper would contact.

  • Strut (suspension)

    A suspension strut combines the primary function of a shock absorber (as a damper), with the ability to support sideways loads not along its axis of compression, thus eliminating the need for an upper suspension arm.

  • Strut Boot

    A flexible protective boot that keeps dirt and debris away from the polished upper shaft and upper shaft seal.

  • Strut Mount

    A mounting insulator between the vehicle and the strut. Front strut mounts often include a steering pivot bearing or bearing plate.

  • Strut Tower

    The panels or structural members in a unibody to which the upper strut mounts are bolted.

  • Sway Bar

    A component that's often used in a suspension system to control body roll. A sway bar may be used on the front and/or rear suspension to help keep the body flat during cornering/maneuvering.

  • Tie Rod

    A part of the steering linkage that connects the steering arms on the knuckles to the steering rack or center link.

  • Tie Rod End

    A flexible coupling in the steering linkage that connects the tie rods to the steering knuckles.

  • Trailing Arm

    A suspension element consisting of a longitudinal member that pivots from the body at its forward end and has a wheel hub rigidly attached to its trailing end.

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