Shock Absorber and Strut Assembly Buyer's Guide
- The shock absorber is a mechanism that dampens, shakes, and bounces when driving on rough and uneven roads
- The suspension strut is a damping mechanism, which basically acts as a shock absorber that provides structural support by carrying the weight of the vehicle
- OEM replacement shock absorber and strut kits can cost anywhere between $30 and $3,300
- These kits are available individually, but it is recommended to replace them in sets of two or four.
Shock absorber and strut kits are simple mechanisms that work to provide a smooth ride and handling to a car. As part of the suspension system, they help vehicles adjust to varying road conditions while minimizing unwanted motions.
In a nutshell, this component controls the up and down movement of the wheels so the car’s body doesn’t bounce excessively. Each assembly is made from shock absorbers, struts, and springs. The shock absorber and strut kit combine these three important parts into one easily serviceable component.
Most modern vehicles come with struts in the front and rear, both of which are designed to dampen the impact inflicted by rough terrains. Your front strut assembly is specifically designed to keep your auto cruising smoothly by absorbing the forces caused by road irregularities.
There are independent suspension systems like the MacPherson strut that use front suspension in the assembly. This strut is already the front suspension of the vehicle with all the important parts rolled into one. For example, it already includes the front shock absorber housed with the coil spring and works as a structural assembly under the vehicle-all in one. This is usually the design of more modern and newer vehicles.
To understand what the shock absorber and strut kit is for, let’s take a closer look at what these parts are and how they function in a vehicle.
What are the shock absorbers?
The shock absorber is a component of a vehicle’s suspension system that plays a key part in improving ride quality. As its name suggests, it is a mechanism that dampens, shakes, and bounces when driving on rough and uneven roads. It is commonly confused with springs because they have a similar use yet they function differently.
Springs vs shock absorbers
Springs work by storing energy, while shock absorbers work to dissipate energy. Let’s say you made a quick turn and your car leans on one side. Without the shock absorber, the spring will store the energy and push the car to lean on the opposite side.
Dampening the movement and dissipating the energy keeps your car stable and prevents rolling from one side to the other. The resistance from shock absorbers also depends on the velocity of movement. Quick movements are absorbed more, while slow movements are absorbed less.
How does a shock absorber work?
Over the years, engineers have innovated on the design of shock absorbers and have developed several kinds of valves. However, its basic design has remained unchanged for almost a century.
Shocks are basically hydraulic chambers with an internal perforated piston and rod. This sealed chamber can either be hydraulic or pneumatic. Hydraulic chambers are filled with hydraulic fluid, while pneumatic ones are filled with compressed gas.
When a car drives over uneven surfaces, the shock causes the piston to move into the chamber. This movement is dampened by gas or fluid in the chamber. This resistance controls the movement of the rod as the gas or liquid it is forced to pass through the piston’s tiny holes.
Types of shock absorbers
This type of shock absorber is most commonly found in cars, SUVs, vans, and light trucks. As its name suggests, it is made up of two cylinders: an inner cylinder where the piston moves and an outer cylinder which acts as a reservoir for the hydraulic fluid.
The monotube design is comprised of a single cylinder which is divided into sections. The chamber is split into two separate areas that hold gas and fluid. The internal piston of monotube shock absorbers is wider than that of a twin-tube.
How long do shock absorbers last?
The shock absorbers on your vehicle are built to last at least 50,000 miles. Their lifespan may vary depending on what vehicle you drive, your individual driving habits, and the kinds of roads or terrain you drive on. It's best to consult a mechanic if your shock absorbers has prematurely failed.
What are Struts?
The suspension strut is a damping mechanism basically acts as a shock absorber that provides structural support by carrying the weight of the vehicle. It is mounted inside a coil spring, combining the spring and shock absorber into one component. The strut also plays a role in the car’s alignment and steering system.
Most of today’s cars are fitted with a MacPherson strut suspension. This type of strut is connected to the body of the vehicle and the hub carrier. It is normally used on the front wheels because it doesn’t take up a lot of space horizontally, unlike a double-wishbone suspension. For such a simple mechanism, it has a significant role in making a car’s ride smooth.
You can read more information in our article "Loaded vs. Unloaded Strut: What’s the Difference?".
Advantages of having a good shock absorber and strut kit
The benefits of having a good shock absorber and strut kit can be described by 3 C’s.
Unlike tires that make a certain number of rotations based on mileage, your suspension system will go through countless compressions in a single mile. The condition of your shocks and struts affect its ability to absorb vibration and imperfections of the road. Having a good kit installed gives a car a smoother ride, and lessens bouncing even when driven over bumps and uneven terrain.
One of the functions of a car’s suspension system is to help the tires maintain contact with the road. Shocks and struts maintain vehicle stability by controlling how weight is shifted between the wheels. When a car puts all its weight on one side during cornering, it doesn’t roll over because of the force of the shocks on the other side which pushes the wheel out towards the road’s surface.
Most importantly, good shocks and struts help in improving a vehicle’s handling. This means that the car can brake without the front-end diving onto the pavement.
Shock Absorber Removal and Strut Assembly Installation
Although the shock absorber and strut assembly are pretty reliable components, you still need to carry out a few maintenance procedures in order to prevent them from getting damaged prematurely. Then again, if you no longer have any choice, you better act fast and install a new one right away. Here are a few steps that you can follow when installing brand-new shock absorbers and strut assembly.
Shock absorber installation guide
Difficulty Level: Difficult
- Floor jack
- Flat-head screwdriver
Step 1: Using a floor jack, raise your vehicle so you could easily see the shocks that you intend to replace.
Step 2: Remove the lug nuts using a ratchet, pull the wheel so that you'll be able to see the shocks clearly.
Step 3: Remove the clips in the brake line using a flat-head screwdriver. In some vehicles, you may skip this step.
Step 4: Remove the top nut of the damaged shocks using a wrench and then proceed in detaching the washer and bushing.
Step 5: By removing the nuts below the shocks, you may now detach the damaged absorber from the suspension system.
Step 6: You can now install your brand-new shock absorber by following the instructions in the service manual.
How to Install a Strut Assembly like a Pro
When replacing your car's damaged strut assembly, there are two options available for you: a "complete strut assembly" or the "bare strut".
By replacing the damaged system with a complete strut assembly, you might end up spending more as compared to replacing just one part. Then again, you'll be saving more money in the long run because you won't have to worry about replacing the components individually. With a complete strut assembly, you'll be able to replace the worn out springs that your car has been using for a long time.
If you're looking for information about shocks and struts replacement cost, you may read our article here.
Your car’s strut assembly offers structural support for the suspension and dampening features, so its components are made to withstand lots of movement, friction, and heavy load. Over time, however, it will wear out. Good thing strut replacement is manageable as long as you have the skills and tools. Here’s what to do:
Difficulty level: Moderate
- Coil spring compressor
- Jack and jack stands
- Lug wrench
Step 1: Loosen the lug nuts of the front wheels with a lug wrench, but don’t remove these nuts yet. Remove the hub caps if needed. Then jack up your car and support it with jack stands.
Step 2: Remove the lug nuts in order to remove the front wheels. Depending on your car make and model, you might need to remove brake line clips or other parts to get access to the struts.
Step 3: Remove the old strut assembly’s top nuts using a socket or wrench. However, don’t remove the center nut. Mark the lower mounting location of the strut on the hub for easier installation later on.
Step 4: Unscrew the bolts that link the struts to the hub and pull out the strut assembly from the car. Then mark the top mounting location for future reference.
Step 5: While the old strut kit is placed on a work bench, compress the spring with a spring compressor so you could remove the retaining washer and top center nut. Pull out the strut assembly, starting from the lower part of the spring.
Step 6: Slide the new strut kit into the spring and reposition the top mount, using the mark you’ve made as a guide. Then reinstall the top nut and retaining washer. Tighten the top nut by following torque specifications. Carefully loosen the compressor to remove it from the struts.
Step 7: Attach the new assembly to your vehicle, making sure that you follow the old assembly’s exact position. Loosely reattach the top mounting nuts of the assembly to attach it onto the engine compartment frame. Adjust the bottom mount until it’s perfectly aligned with the marks you made earlier. Then torque the bolts and top nuts according to the manufacturer’s torque specifications.
Step 8: Reinstall all the other parts you’ve removed—brake line clips, wheels, and hubcaps. Take the car for a test drive.