The Suspension System & Its 7 Parts

The Suspension System & Its 7 Parts

What is Car Suspension?

Car suspension is a system that enables a vehicle to drive smoothly while holding the road to maximize ride quality. If a car’s engine is performing well, but the driver cannot control the vehicle, said engine never gets the opportunity to output any power. Ensuring that the vehicle’s tires stay in contact with the road while creating productive friction is what the auto suspension is designed for.

The handling of a vehicle is its ability to maneuver, accelerate, and brake safely.  The suspension also cradles the passenger compartment to spare those within the car from feeling every bump in the road. There are a few different types of suspension systems for cars and trucks. It may be helpful to know what kind of suspension a car has. The main components to an auto suspension system are the tires, springs, and dampers.

Ball Joints

The ball joints (fig. 8-7) are connections that allow limited rotation in every direction and support the weight of the vehicle. They are used at the outer ends of the control arms where the arms attach to the steering knuckle. In operation, the swiveling action of the ball joints allows the wheel and steering knuckle to be turned left or right and to move up and down with changes in road surface.

Since the ball joint must be filled with grease, a grease fitting and grease seal are normally placed on the joint. The end of the stud on the ball joint is threaded for a large nut. When the nut is tightened, it force fits the tapered stud in the steering knuckle or bearing support.


Specialized Suspensions: The Baja Bug

The Baja Bug has multiple coil-over systems, an aftermarket item that combines both the spring and shock absorber in one adjustable unit. Photo courtesy Car Domain

­For the most part, this article has focused on the suspensions of mainstream fron­t- and rear-wheel-drive cars — cars that drive on normal roads in normal driving conditions. But what about the suspensions of specialty cars, such as hot rods, racers or extreme off-road vehicles? Although the suspensions of specialty autos obey the same basic principles, they do provide additional benefits unique to the driving conditions they must navigate. What follows is a brief overview of how suspensions are designed for three types of specialty cars — Baja Bugs, Formula One racers and American-style hot rods.

Baja Bugs

The Volkswagen Beetle, or Bug, was destined to become a favorite among off-road enthusiasts. With a low center of gravity and engine placement over the rear axle, the two-wheel-drive Bug handles off-road conditions as well as some four-wheel-drive vehicles. Of course, the VW Bug isn’t ready for off-road conditions with its factory equipment. Most Bugs require some modifications, or conversions, to get them ready for racing in harsh conditions like the deserts of Baja California.


One of the most important modifications takes place in the suspension. The torsion-bar suspension, standard equipment on the front and back of most Bugs between 1936 and 1977, can be raised to make room for heavy-duty, off-road wheels and tires. Longer shock absorbers replace the standard shocks to lift the body higher and to provide for maximum wheel travel. In some cases, Baja Bug converters remove the torsion bars entirely and replace them with multiple coil-over systems, an aftermarket item that combines both the spring and shock absorber in one adjustable unit. The result of these modifications is a vehicle that allows the wheels to travel vertically 20 inches (50 centimeters) or more at each end. Such a car can easily navigate rough terrain and often appears to "skip" over desert washboard like a stone over water.


7. Frame

The frame is the primary component of the suspension system. It carries the entire weight of the suspension, keeping all the parts connected and working properly. 

Dampers: Shock Absorbers

Shocks, or shock absorbers, control unwanted spring motion through a process known as dampening. © 2018 HowStuffWorks

Unless a dampening structure is present, a car spring will extend and release the energy it absorbs from a bump at an uncontrolled rate. The spring­ will continue to bounce at its natural frequency until all of the energy originally put into it is used up. A suspension built on springs alone would make for an extremely bouncy ride and, depending on the terrain, an uncontrollable car.

Enter the shock absorber, or snubber, a device that controls unwanted spring motion through a process known as dampening. Shock absorbers slow down and reduce the magnitude of vibratory motions by turning the kinetic energy of suspension movement into heat energy that can be dissipated through hydraulic fluid. To understand how this works, it’s best to look inside a shock absorber to see its structure and function.


A shock absorber is basically an oil pump placed between the frame of the car and the wheels. The upper mount of the shock connects to the frame (i.e., the sprung weight), while the lower mount connects to the axle, near the wheel (i.e., the unsprung weight). In a twin-tube design, one of the most common types of shock absorbers, the upper mount is connected to a piston rod, which in turn is connected to a piston, which in turn sits in a tube filled with hydraulic fluid. The inner tube is known as the pressure tube, and the outer tube is known as the reserve tube. The reserve tube stores excess hydraulic fluid.

When the car wheel encounters a bump in the road and causes the spring to coil and uncoil, the energy of the spring is transferred to the shock absorber through the upper mount, down through the piston rod and into the piston. Holes perforate the piston and allow fluid to leak through as the piston moves up and down in the pressure tube. Because the holes are relatively tiny, only a small amount of fluid, under great pressure, passes through. This slows down the piston, which in turn slows down the spring.

Shock absorbers work in two cycles — the compression cycle and the extension cycle. The compression cycle occurs as the piston moves downward, compressing the hydraulic fluid in the chamber below the piston. The extension cycle occurs as the piston moves toward the top of the pressure tube, compressing the fluid in the chamber above the piston. A typical car or light truck will have more resistance during its extension cycle than its compression cycle. With that in mind, the compression cycle controls the motion of the vehicle’s unsprung weight, while extension controls the heavier, sprung weight.

All modern shock absorbers are velocity-sensitive — the faster the suspension moves, the more resistance the shock absorber provides. This enables shocks to adjust to road conditions and to control all of the unwanted motions that can occur in a moving vehicle, including bounce, sway, brake dive and acceleration squat.



Struts are sometimes used in place of shocks to dampen the movement of the springs. They’re mounted inside a coil spring and contribute to the structural support of your truck. In contrast to shocks, which control how quickly the truck’s weight is transferred, struts bear the weight of the vehicle.

4. Stabilizer Bar

The stabilizer bar is a car suspension component t

The stabilizer bar is a car suspension component that maintains body balance when the car turns. When the car turns, it will undoubtedly create a centrifugal force, which is the force from an object that turns or rotates to get out of the track.

When the car is used at high speed and suddenly turns the car, there will be a greater centrifugal force than when used at a low speed. The centrifugal force that is too large will usually make the car overturn if it turns suddenly at high speed. The stabilizer component will help to stabilize the car so that it doesn’t turn over.

In general, the stabilizer is an iron rod connected or connected between the lower arm of the left and right wheels. In the middle, it will usually be connected to the car body. Stabilizer iron rods typically have reasonably high elasticity so that their performance follows the car’s specifications.


Every suspension includes various rods and other connecting pieces that collectively keep the wheels where they’re supposed to be relative to the rest of the vehicle. Most of these linkages are solid metal parts that rarely fail except in major accidents. However, sometimes linkages and associated bushings are sold together, and the failure of a bushing can necessitate replacing the whole assembly.

Why do vehicles need a suspension?

A suspension system in a vehicle serves to isolate the occupants of a vehicle from the vibrations that arise due to traversing the contours of the road surface, while helping the driver remain in complete control.

A ride in the car is more comfortable than on a bicycle, partially because of better isolation from the road (Photo Credit : Africa Studio/Shutterstock)

In order to have maximum control of a vehicle, it is imperative to be in maximum contact with the traversed surface, which appears to be in contrast with the original purpose of suspension—isolation from the road surface. Thus, suspension systems are designed to achieve a trade-off between occupant comfort and ride handling.

Another frequently overlooked function of suspension systems is the absorption of shock loads to prevent any damage to the chassis to which they are connected.

Sprung and unsprung mass

The part of the vehicle supported by the suspension system is known as the sprung mass. This usually includes various components, such as the driveline components, like the engine and transmission, vehicle body and chassis frame, as well as the passengers and their cargo.

The unsprung mass consists of the parts that are not supported by the suspension. These include the wheels, brake assemblies, differentials, drive axles etc.

In order to maximize control of a vehicle, a high sprung to unsprung mass ratio is desirable. A higher sprung mass ensures more force on the springs and wheels—and consequently, greater traction. However, there is only a certain extent to which the sprung mass of a vehicle can be increased without affecting handling and the adequacy of power produced by the engine. Thus, the sprung to unsprung mass ratio is a trade-off between traction and weight.

2. Shock Absorber

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A shock absorber is a component of a car suspension that functions to dampen up and down movements or oscillations caused by springs that absorb various shocks or vibrations from the road surface.

In a Shock Absorber, there is a liquid that acts as a shock absorber oil. The Shock Absorber fluid will absorb the spring’s oxylation through the resistance of oil flow in a small hole or orifice when the piston moves in a cylinder contained in the shock absorber.

The Shock Absorber works because when there is compression, the valve will open, and the oil will flow very easy to prevent damping. When expansion, the valve will close, and oil will flow in a small hole, causing damping.

Shock absorbers in a car are divided into several types. The shock absorber consists of a single type shock absorber and a double-acting shock absorber based on how it works.

Based on the construction, these components are divided into twin-tube and monotube types. Meanwhile, based on the working medium, the shock absorber consists of a shock absorber type containing gas and a hydraulic variety.

Hydraulic power steering

Many vehicles are equipped with power steering. Of the two types of power steering, hydraulic systems (i.e., those that use a high-pressure fluid to help the driver turn the wheels) are more failure-prone. Fluid can leak from high-pressure lines, delicate valves occasionally wear out, the belt that drives the power steering pump can loosen or break, and eventually the pump itself may fail.

4. Rods

Rods are metal links that connect all the different parts of the suspension system together. These important components are built to last the lifetime of the vehicle. The only way they may break is if your car is involved in a vehicle accident.

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Advancements in suspension technology: Adaptive suspension

Adaptive suspension systems allow for adjustments based on human preferences and can even map out the system configuration based on external conditions (Photo Credit : Everyonephoto Studio/Shutterstock)

An adaptive suspension system consists of an active suspension system linked to cameras, sensors and the GPS system built into a vehicle. This enables the onboard computer to make adjustments to the suspension configuration in anticipation of the terrain to come, thereby ensuring smoother ride quality and better handling.

Ride height control is another feature found in hydropneumatic suspension systems. By changing the amount of oil in the hydraulic column, the height of the vehicle can be varied slightly. A lowered car is more stable and easier to handle, while a high-positioned car can effectively clear underbody obstacles, such as high speed breakers, surface undulations, or even water from flooding.


Welcome to We are an automotive mechanic blog that helps mechanics and car users to find the most recent and accurate technical and repair information for their cars. We recently created this blog site to enable us to share our knowledge with other automotive mechanics and car owners.

Why Car Suspension Repair is Important

When someone is driving a vehicle, the most important concern is obviously safety. A healthy suspension system enables the driver to operate the vehicle confidently because it’s main purpose is to keep the vehicle on the road. Routine inspections to the suspension will confirm that the tires will stay in contact with the road beneath them, and that the vehicle will steer properly and predictably.

Any signs of suspension issues should be investigated by a professional to avoid unwanted and potentially dangerous performance problems with a vehicle. Drivesmart’s Elite plan covers a vehicle’s full suspension system. Repairing or replacing things like bushings, bearings, ball joints, spindles, torsion bars, and more can be simple; with little or no cost to you with Drivesmart’s Elite coverage.


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