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What Are Struts On A Car?

What Are Struts On A Car?

By PattyKay Lilley

Are you thinking about buying a car but are feeling overwhelmed by all the intricacies that come with it? Understanding the basics of auto mechanics is important when making decisions about which parts and features to opt for.

One major factor in many kinds of vehicles is struts, often referred to as shock absorbers. But what exactly are these components – why are they important, and does your car need them? In this blog post, we’ll break down everything there is to know about struts on cars so you can be better informed before making any purchasing decisions.

What Are Struts On A Car?

Struts are vital parts of a car’s suspension system. They integrate several different suspension parts into one compact assembly. Struts include components such as a coil spring, spring seats, shock absorbers, strut bearing, and steering knuckle. They work together to absorb shocks and bumps from the road, providing a smoother ride.

Struts are not just about comfort, though. They play a crucial role in maintaining the balance and stability of the car. By absorbing the impact of road conditions, struts help keep the tires firmly in contact with the road. This is particularly important in situations such as abrupt stops or sharp turns, where the stability of the car is critical.

Furthermore, struts contribute to the car’s steering system. As they are connected to the steering knuckle, they aid in steering the wheels of your vehicle. Struts allow your car to navigate curves and turns smoothly, making your drive safer and more comfortable.

In short, struts are more than just shock absorbers. They contribute significantly to the comfort, balance, stability, and steering of your car. Understanding how struts function can help you better maintain your vehicle and ensure a safer, smoother driving experience.

See more: What Is A Compact Car?

Difference Between Shocks and Struts

Difference Between Shocks and Struts

While it’s common to hear shocks and struts used interchangeably, they are two distinct parts with different functions. Both components contribute to your vehicle’s ride and handling, but they operate differently. Shocks are individual components of the suspension system, while struts are a major structural component of the chassis and suspension system.

What Shocks Do

Contrary to what many believe, conventional shock absorbers do not support vehicle weight. Instead, their primary role is to control spring and suspension movement. This is achieved by converting the kinetic energy of suspension movement into thermal energy or heat energy, which is then dissipated through the hydraulic fluid.

The resistance a shock absorber develops is dependent on the speed of the suspension and the number and size of the tiny orifices in the piston. All modern shock absorbers are velocity-sensitive hydraulic damping devices – the faster the suspension moves, the more resistance the shock absorber provides. Because of this feature, shock absorbers adapt to changing road conditions and reduce the rate of:

  • Bounce
  • Roll and sway from worn shocks losing the ability to control the rate of weight transfer
  • Brake dive and acceleration squat

Shock absorbers operate on the principle of fluid displacement on both the compression and extension cycle. A typical car or light truck will have more resistance during its extension cycle than its compression cycle. While the compression cycle controls the motion of a vehicle’s unsprung weight, the extension cycle controls the heavier sprung weight.

Shock Components

Technician inspecting shocks. Shock absorbers are essentially oil pumps. A piston is affixed to the end of the piston rod and works against hydraulic fluid in the pressure tube. As the suspension travels up and down, the hydraulic fluid is forced through the orifices within the piston. But these orifices only allow a minimal amount of fluid through the piston. This action slows down the piston, which in turn reduces spring and suspension movement.

What Struts Do

The strut is a common damper type used on many of today’s independent suspension, front wheel drive vehicles, and some rear wheel drive vehicles. A strut is a significant structural part of a suspension. It replaces the upper control arm and upper ball joint used in conventional suspensions. Due to its design, a strut is lighter and occupies less space than the shock absorbers in traditional suspension systems.

Struts have two main functionalities. Firstly, struts perform a damping function like shock absorbers. Internally, a strut is similar to a shock absorber. A piston is hooked to the end of the piston rod and operates against hydraulic fluid to manage spring and suspension movement.

Just like shock absorbers, the valving generates resistance to forces created by the up and down motion of the suspension. Also, like shock absorbers, a strut is velocity-sensitive, which means that it is valved so that the amount of resistance can increase or decrease depending on how fast the suspension moves.

Secondly, unlike shock absorbers, struts provide structural support for the vehicle suspension, hold up the spring, and keep the tire in an aligned position. Additionally, they bear much of the side load placed on the vehicle’s suspension. As a result, struts affect ride comfort and handling as well as vehicle control, braking, steering, wheel alignment, and wear on other suspension components.

Strut Components

Typically, struts consist of a strut housing to provide rigid structural support for the assembly and a damping unit within the strut housing to control spring and suspension movement. On most struts, the bottom of the body attaches to the steering knuckle, which in turn connects to a lower control arm through a lower ball joint.

A complete strut assembly includes all the components required for strut replacement in a single, fully-assembled unit. It combines the strut housing, damping unit, along with a coil spring to support the vehicle’s weight.


Many drivers have questions about the role and function of struts in their vehicles. From understanding how they affect ride comfort and handling, to knowing when they need replacing, here are answers to some commonly asked questions.

How often do I need to replace my car’s struts?

The lifespan of struts can vary significantly based on the vehicle and driving conditions. Generally, most manufacturers recommend inspecting or replacing your struts every 50,000 to 100,000 miles. However, if you notice symptoms such as a rough or bouncy ride, excessive body roll when turning, or uneven tire wear, it might be time for a strut replacement.

Are struts and shocks the same thing?

Though the terms are sometimes used interchangeably, struts and shocks are different components of a vehicle’s suspension system. Shocks, or shock absorbers, control the movement of the spring and suspension, whereas struts are a structural part of the suspension system and provide support for the vehicle’s weight. While both contribute to ride comfort and handling, they have distinct mechanisms and functions.

Can I drive my car with bad struts?

Driving with worn or damaged struts is not advisable as it can compromise the safety and control of your vehicle. Bad struts can lead to poor handling, increased stopping distances, and an overall rougher ride. Most importantly, they can cause excessive wear on other components of your suspension system, leading to more costly repairs down the line.

Do I need to replace all four struts at the same time?

While it is not strictly necessary to replace all four struts at the same time, it is generally recommended. Replacing all struts together ensures a balanced and stable ride, as the new struts will operate at the same level of efficiency.

If only one or two struts are replaced, the old ones may not be able to keep up with the new ones, potentially resulting in uneven performance and reduced handling and safety.

Final Thought

Understanding the role and function of struts in your vehicle is crucial for maintaining a comfortable and safe driving experience. Struts not only contribute to the overall ride comfort but also play a significant role in ensuring your vehicle’s stability and control.

The process of maintaining and replacing struts when necessary may seem daunting. However, armed with the right knowledge and understanding of their function, you can make informed decisions about your vehicle’s maintenance.

It’s important to note that the condition of your struts can significantly impact other aspects of your vehicle, from steering and braking to wheel alignment. Thus, keeping them in good working order is not just about maintaining ride comfort, but crucial for the overall health of your vehicle.

In conclusion, struts are more than a car part; they are an integral component of your vehicle, ensuring safety and smoothness on the road. Regular inspections and timely replacements are essential steps to prolonging your vehicle’s lifespan and ensuring a safer, smoother ride.

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