Struts and Shocks: Understanding the Difference

Struts are very similar to shock absorbers, in both appearance and function. This article, however, explores the concept of struts, highlighting the similarities and differences it shares with shock absorbers.

What is a strut?

A strut is a suspension system component that is made of a coiled spring and a shock absorber. The shock absorber is fitted either above, below, or in the middle of the coil spring.

In struts, the spring absorbs larger bumps or shocks and also supports the weight of the vehicle. The shock absorber furthermore supports the vehicle’s weight and prevents the vehicle from bouncing when it hits a bump.


Functions of Struts

Struts are considerably different because they add more features and functionality. They are a structural part of the suspension system and are bolted to the chassis of the vehicle on the top, and they come down through.

  1. They make provision for a coil spring to be mounted and this is what maintains the height of the vehicle, so we have a plate in here for the spring.  
  2. Struts replace the upper control arm and it connects directly to the knuckle on the car, which in many cases gives us a minor ability to adjust alignment. An alignment is always needed when replacing a strut.
  3. Most modern shocks also contain nitrogen gas to prevent “cavitation” and air bubbles which can accelerate wear in the valve assembly.

Types of struts

MacPherson Strut

The McPherson Strut is the most popular type of struts. This is the system used in most modern passenger cars. A simpler coil spring, deployed in the rear supports its function. The MacPherson Strut system includes a damper/shock absorber and a simple assembly of coil springs.

The main purpose of the spring is to store energy resulting from a sudden road jerk. The damper uses hydraulic fluid to distribute this energy in heat form. The system together limits unnecessary movements of the car as a result of bumpy or rough road surfaces.

MacPherson Strut

Air strut

An air strut is a strut with an air spring incorporated into it. It composes of height sensors that send electronic signals to the suspension computer, thereby, relaying the height of the vehicle.

Air Strut

Importance of Struts

Excellent distribution of tension

The presence of struts as part of the front-end suspension design massively reduces the stress that should be experienced by one part of the vehicle while navigating corners and bends at high speed. They give vehicles more control over gravitational forces that tend to work against them in either direction while going through the bend.

This, in turn, reduces the stress and tension that is placed on either side of the vehicle. This design allows excellent load distribution that doesn’t affect vehicle stability when driving on straight parts of the road.

Better weight distribution means more of the tire surface is solidly pressed to the ground and this results to better handling and traction. Incorporating a strut bar greatly reduces the amount of sway the vehicle experiences as well, especially while taking those bends.

Manages High center of gravity

As a result of their design, some vehicles have a high center of gravity and this causes them to roll over easily. This is usually experienced in vehicles like trucks and SUVs, because, they are higher and farther away from the ground than other cars.

Gravity, therefore, affects them more. In other words, struts are used because they distribute the roll force more evenly. This stabilizes the vehicle and keeps it upright when speeding through turns.

Wear and Tear is greatly reduced

Since struts are part of the suspension system and could be included in the front-end suspension design, their presence helps reduce the irregular stress other vehicle components experience.

This improves and elongates the shelf life of these other components because the disproportionate shocks and stress are received and absorbed by the struts thereby, creating balanced stress on the vehicle. The need to replace components due to premature failure is therefore reduced.

Improved comfort

Struts are mainly used in the design of front-end suspension of vehicles. This is so because the navigation and control of vehicles are in front so it is more suitable to incorporate a component that makes handling easy here.

They can also be added to the rear part of the vehicle. Their presence in the rear ensures that the vehicular structure is stiffer which in turn reduces the stress escaping the suspension system. Rear struts are engaged when the front one doesn’t manage the stress very well due to the constant plying of rough paths.

Multi design option

Struts come in different shapes and sizes. This variance makes it available and suitable for different car designs and models. Each type of strut offers specific advantages and this should be put into consideration while purchasing and installing new struts.

For instance, a Mustang of 2005 backward, benefitted from the triangular brace design. This is because the strut allows additional stiffening due to its shape. The installation process of a strut is pretty easy. Feel free to try other shapes to know the one that functions best in your car.

DIY Steps to Install a strut

  • Remove the nuts from your strut tower.
  • Place the bracket of the strut bar over the struts with the nuts on top.
  • Tighten the assembly.
  • Do the same thing on the other side, and then adjust the bolts to the required length.
  • Make sure that your lock nuts are tightened appropriately and no dynamic tension is placed against the bar.    

How are Struts different from Shocks?

Before we answer this, we first need to have a deep insight into shocks. We need to understand its meaning and function, as well as have an image of it to guide us through.

What is a shock absorber?

A shock absorber

A shock absorber is a component of a vehicle that dampens the vehicle’s spring oscillations. It contains hydraulic fluids inside it and is sealed by a valve. The main function of a shock absorber is to keep the tires pressed to the ground; eliminate or minimize bounce; and improve traction and vehicle control.

The plunger of the shock is connected to the body of the vehicle and the body of the shock connected to the wheel. The plunger moves up and down the body of the shock that contains the hydraulic fluids.

Image shocks location

The rate at which the plunger travels through the fluid and the rate with which it returns back to its normal position is controlled by a series of valves. The working principles of a shock absorber can be likened to a medical syringe used to inject patients. This is because they have very similar patterns of movement. Watch the video below to see just how it works.

To find out more about the meaning, types, and functions of shock absorbers, click here.

A Comparison between Struts and Shocks

As stated earlier, a strut is a component of your vehicle's suspension system, which is connected to the wheels and the chassis of your car. Struts perform two main functions.

The Design of Struts differ from Shocks:

The primary difference between a strut and shock can be found in the design and implementation of the suspension systems. Struts integrate Shocks in their structure while Shocks exist independent of struts. To add to this, the strut is a structural part of the vehicle's suspension system while the Shocks are not.

Struts dampen shock and vertical forces just like shock absorbers:

This can also be seen in their internal structures as both struts and shock absorbers are very similar internally. To control spring and suspension movement in both, a piston is attached to the end of the piston rod and this works against hydraulic fluid.

Basically, therefore, the valving in struts is similar to what we have in shock absorbers. They provide resistance to the up and down movement of the suspension system.

Unlike shock absorbers, struts have a second job which is to provide structural support for the vehicle's suspension:

This results in struts having a huge impact on comfort while driving and also ease of handling. It also affects vehicle control, braking, steering, wheel alignment, and wears on other suspension components, including the tyres.To see how struts and shocks work, this video tells it all!

Other differences are highlighted below:

  • All vehicles will use a shock or a strut on each of the four corners. Several use struts at the front with a shock absorber in the rear.
  • Struts are used on vehicles without an upper control arm and connect to the knuckle. On the contrary, vehicles with an upper and lower control arm (independent suspension) or a solid axle (on the rear) use shock absorbers.
  • A strut is also a crucial part of the vehicle's steering system and greatly affects alignment angles. Camber and caster angles are also usually adjusted right on the strut itself.
  • A strut is also a pivot point for the vehicle's steering system and contains a coil spring. Because of this, an alignment is always needed when replacing a strut. This is also the reason that struts are typically more expensive than shocks.

Difference between Shocks and Struts

Disadvantages of Strut Bar

Bad placement location in some vehicles

The position of strut bars is very crucial to performing efficiently. This means that we should make sure the strut is not placed too high. The installation points of some cars make the purpose of installing struts defeated and in some cases, the bonnet of the car can’t be closed.

People that live in urban settlements where traffic is highly controlled and drivers are very careful do not need to install struts. It is an unnecessary investment. Installing struts adds negligible weight to the vehicle and this can impact fuel economy. There is no need to reduce sway on low-speed turns because the danger of rolling or transferring too much energy is negligible.

Reduces car flexibility

Sometimes the strut doesn’t fit. This causes the car to become stiff because it is too stable, which means you can lose its handling rather easily. This is because they are transferring all the energy to the opposite side of the vehicle, as this happens the tires become a little bit stiff.

Sometimes they are installed for pure Aesthetic purposes

People love modifications that look great and actually serve a purpose. That said, strut bars aren’t just an aesthetic modification by any means, they are present to serve a purpose but most people install them just for the looks.

If you’re expecting a drastic change in the way your car handles after installing strut bars, you’ll probably be disappointed. Expecting a drastic change in the handling of your vehicle after installing struts would leave you disappointed. But if you feel your vehicle could benefit from the presence of a strut bar, set up an appointment with your auto-mechanic.

Rigidity is increased

Strut bars keep everything balanced, therefore, when driving in off-road situations, it is better not to have extra balancing strut front-end suspension provides. This way, the system acts independently.

For instance, if you have a strut brace installed, and your front left wheel hits a bump, the effect, transferred across the suspension system will also be felt on the front right wheel.

How often should I replace my struts or shocks?

Struts and shocks are in constant use and often endure rough use on uneven and rough grounds. This results in their expected average lifespan of 50,000 to 100,000 miles reduce significantly resulting in earlier wear out.

While it is possible to drive with old or damaged shocks and strut assemblies, it doesn’t feel pleasant. Furthermore, extreme wear on these parts can reduce a vehicle’s handling and braking performance, ultimately compromising safety.

Old and new Struts

What is the cost of replacing struts or shocks?

The cost of replacing your strut or shock falls between $450 and $1,100. This is for parts and labor combined. While individual strut or shock assembly costs around $150 to $900, the cost of labor for replacing a strut or shock assembly can range anywhere between $150 to $300 per assembly. These prices can vary considering your vehicle’s suspension system and location.

Latest posts

change car oil
change car oil
change car oil