How Your Car’s Suspension Works

How Your Car’s Suspension Works

Whether you drive a sports car or big truck, its horsepower, your new high-performance wheels and carbon spoiler are useless if your tires don’t grip the road as they should or you can’t control your ride. This is what your suspension is made for and when it comes into play. It does a couple of essential jobs at the same time, supporting the weight of the vehicle, providing steering stability with proper handling, and maximizing the friction between your tires and the road surface.

In a perfect world, your suspension system would have little job to do. However, in reality, our roads aren’t perfectly smooth and have a lot of potholes, bumps and other imperfections. If they are not addressed and handled by your suspension system, your driving will become the worst experience you have ever had. Fortunately, your suspension system absorbs and handles most of them, ensuring a smooth and comfortable ride. 

Another problem your suspension system has to deal with is the force created when your vehicle is going around the turn. When you’re cornering, your vehicle begins to lean to one of the sides, increasing body roll and putting a lot of stress on left or right tires. Your suspension system compensates this force, keeping your vehicle moving smoothly. A similar problem appears when you are braking rapidly or depress the gas pedal. As a result, almost all weight of the vehicle is transferred to the front or the rear of your car or truck. If this is not handled by your suspension system, your front or rear tires will lose contact with the road surface, increasing the braking distance and worsening your acceleration.

The suspension system of a modern vehicle is very complex. It consists of a number of parts and components as well as incorporates some steering system parts and even wheels. Its design may vary depending on a vehicle, but there are some key components that can be found in just about any vehicle. One of them is suspension springs, which job is to support the weight of the vehicle and to provide a desired clearance to prevent the underneath of the car from hitting bumps and other road irregularities. Springs can be of different types, including coil springs, leaf springs, torsion bars, air springs and hydraulic springs. 

Today, most cars come equipped with coil springs. They are made from high-grade steel that can withstand high pressure and other extremes. Coil springs perfectly absorb road imperfections, keeping your vehicle running smoothly. The second most popular type of springs is leaf springs. Like their name indicates, they consist of metal layers that rest one on another and are clamped together to support the body of a vehicle. In most cases, it is possible to change the quantity of the leaves to increase the load capacity of the vehicle.

Large vehicles, military vehicles and SUVs usually come with torsion bars. This is another type of suspension spring that can handle heavy weights and impacts. By design, it is a long metal bar that is attached to the vehicle’s frame on one end and to the axle or spindle on the other one. Thanks to the torsion resistance of the bar, it absorbs impacts, doing the same job as other types of springs.

Along with coil springs, leaf springs and torsion bars, which provide a fixed clearance, there are several types of springs that can be adjusted on the fly. One of them is air springs, which are usually found in top market cars equipped with a computer controlled suspension system. The computer operates a high-performance compressor that fills a rubber cylinder (an air spring) with pressurized air. Depending on the needs, air springs can be supplied with more or less pressure to change the ride height. Many vehicles with air suspension allow the driver to adjust the ride with a click on the button. Another type of adjustable springs is hydraulic springs. They act similar to air springs, however, instead of air they are filled with pressurized hydraulic fluid. The springs are also operated by the computer, which relies on different sensors to adjust them on the go.

While suspension springs are designed to support the weight of a vehicle and absorb road impacts, they also need some kind of support to prevent their excessive motion. This is when shock absorbers and struts come into play. They even the movements of the springs to provide a more comfortable and controlled ride. 

Shock absorbers do exactly what their name suggests. They absorb some amount of shock that the springs experience, reducing their rebound and keeping the tires stuck to the road surface. A typical shock absorber is a metal tube with a piston moving within it. The tube is filled with hydraulic fluid that flows up and down through small vents inside the shock absorber. As for a strut, it is actually a shock absorber that is placed inside a coil spring. They do the same job as shock absorbers, yet are more compact and lightweight, which makes them perfect for small cars and trucks.

When a vehicle is going around a turn, its weight sways to the outside of the turn, causing an excessive load on one side of the vehicle. To minimize that impact, many vehicles come equipped with a sway bar or anti-roll bar. It is attached to the frame with the help of bushings and mounts, keeping the vehicle more stable. As a rule, it comes at the rear end of the vehicle, however, more and more vehicles today feature both front and rear sway bars.

Suspension systems have come a long way from simple coil and leaf springs to computer-controlled and operated air and hydraulic systems. The latter become more and more common today, allowing for adjusting the ride of a vehicle on the fly depending on road conditions, the vehicle’s speed and the driver’s habits.

What type of suspension do I have?

All suspension systems can be divided into two major types, including dependent and independent ones. Your vehicle may either have one of them or incorporate both at the same time. The first type of suspension systems can be found on older cars and trucks. The main feature of this suspension design is the left and right wheels connected to each other via a solid axle. It works with just about any type of springs and dampeners, including coil springs, torsion bars or leaf springs. The dependent suspension design allows for better off-road stability and strength, yet provides less driving comfort.

Independent front and/or rear suspension is common for most modern vehicles. It allows every wheel to move independently, which improves driving comfort and handling, while compromising on the off-road capability of a vehicle. Both front and rear independent suspensions work the same. The only difference is that there are no steering system components in the rear. If a vehicle comes with independent suspension in the front and rear at the same time, this greatly improves its ride.

Suspension system troubleshooting

Most suspension system parts and components are designed to survive the test of time and do not require routine maintenance. Suspension parts such as coil or leaf springs, and torsion bars can live the life of a vehicle, while shock absorbers and struts may require a replacement from 50 to 100 thousand miles. 

As a rule, suspension parts do not fail all at once. Being exposed to heavy loads, its components wear slowly, making the ride less comfortable and providing an array of warning signs, including knocking and rattling noises.