What Are Shocks and Struts?

Your car’s shocks and struts are responsible for keeping the vehicle’s body suspended above the wheels and comfortably off the ground while driving. Without them, you’d bounce along the road, making for an uncomfortable and unsafe ride.

Shocks and struts convert the up-and-down movement of the car into energy, which they absorb every time you hit a pothole or a bump in the road. When they wear down, you lose control of the car’s stability, and the car takes longer to stop. Shocks and struts are safety-related as much as they are comfort-related.

What Are Shocks and Struts?

This is a common question that we receive as the terms shock and strut are often used interchangeably. A shock and a strut do the same basic job on a vehicle, damping the movement of the spring and stopping oscillation and bounce.

Even though they have the same function, shocks and struts are completely different parts. A shock cannot be used to replace a strut and a strut cannot be used to replace a shock. A vehicle will have either a shock or a strut at each wheel, never both. Every vehicle was designed with either shocks or struts and your vehicle’s suspension cannot be changed to use the other.

The major difference between shocks and struts is that a strut is a structural part of the vehicles suspension system, whereas a shock is not.

What is a Strut?

A strut is a crucial part of the car’s steering system and greatly affects alignment angles. Camber and caster angles are 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. Struts will have mounts, and sometimes boots and bumpstops within the complete strut.

When replacing struts, you should always replace your boots and bump stops. Coil Springs generally last 300,000 miles and rarely have to be replaced. In some vehicles, you may find a complete strut unit, which we will detail below, that will contain a new spring.

What is a Shock?

Also known as shock absorbers, shocks are parts that help control the rebound movement and impact of the springs and suspension on a vehicle. They are also responsible for ensuring the tires remain in contact with the surface of the road.

Shocks control the springs and suspension by turning kinetic energy into thermal energy that’s dissipated through hydraulic fluid. Key components of the shock absorber that help with this process include a piston, coil and hydraulic fluid.

When a car’s suspension is moving, hydraulic fluid is forced through holes in the piston. Only a small amount is let through, which slows the piston, affecting the movement of the springs and suspension.

The faster a suspension moves, the more resistance a shock absorber has. The effects include a reduced rate of bouncing on the road, swaying and brake diving.

What Do Shocks and Struts Do?

Shock and struts in good condition will help your car handle bumps, rocks, sudden stops, skids, potholes, gusts of wind, or sharp turns. You control the shifts in weight from side to side, front to back, and top to bottom to keep your tires in contact with the road and you maintain control of your vehicle.

They also:

• Maintain your tire’s contact with the road.
• Prevent your tires and wheels from moving up and down too much.
• Contribute to stability as you accelerate, stop and turn.
• Increase driving comfort by absorbing shock and bumps from irregular road surfaces.
• Help control a vehicle’s body movement (side-to-side roll, hop).
• Promote even wear for longer tire life.

Contrary to popular belief, shock and struts do not typically support the weight of your vehicle or any loads that your truck or vehicle might support. The springs do this job. Worn shocks and struts, however, put more stress on the springs and other critical suspension parts.

Without the control that a good shock absorber or strut provides, these other parts will become overloaded, leading to fatigue and premature wear.

How do Shocks and Struts work?

Shock absorbers and struts help stabilize your vehicle’s movements and improve control when turning, braking, accelerating or on rough road surfaces. Today’s vehicles use shock absorbers, struts, or a combination of both.

The fundamental difference is that a damper is a separate component, while the strut combines the damper and other features into a single assembly. Both help stabilizes the vehicle and keeps the tires in contact with the road. Without shock absorbers, your vehicle would bounce down the road.

How long can you expect your shock absorbers or struts to last? That depends. Driving on rough or unpaved roads, towing a trailer, or carrying heavy loads can shorten their lifespan. If used heavily, you might try replacing them after 40,000 or 50,000 miles or sooner. Under normal conditions, 75,000 to 90,000 miles might be reasonable.

What is the difference between shocks and struts?

Shock and struts are often referred to interchangeably, but there are some major differences between them. If your vehicle requires struts, you cannot replace shock absorbers (and vice versa).

Shock absorbers are individual suspension components that help coil springs absorb road impact. Without shocks, the vehicle would spin out of control! They help keep the tires in contact with the road instead of springing up after a bump.

A strut combines the shock absorber and coil spring components into a single unit. Struts not only absorb bumps and shock but also provide structural support. They replace the upper control arm and upper ball joint required on traditional suspension systems.

When to Replace Shocks and Struts?

A general rule of thumb is to replace your shocks or struts between 50,000 and 100,000 miles, but this can vary based on several factors, including the type of roads you regularly drive on.

These components will wear down over time, which means you might not notice any issues right away. However, there are some things you can be on the lookout for:

• Increased bumpiness: The main job of shocks and struts is to improve handling, so if you notice that your car feels a lot bumpier or shakier on the road, it’s a good idea to get these components looked at.
• Brake problems: Damaged struts and shocks can cause issues with other parts of your vehicle. Brake diving can feel like your car is lurching forward when you step on the brake pedal, which can be a sign of wear and tear.
• Tire wear: Checking your tires often is important for many reasons, and their condition can point you in the direction of getting your shocks or struts looked at. Suspension damage can cause cups or scalloped dips in tire treads.
• Leaks: Fluid leaking on the outside of your shocks or struts is another sign something might be wrong. A lack of fluid will prevent them from being able to absorb impacts and bumps.

Taking your vehicle to a trained auto tech can help you identify the source of any problems and allow you to replace your shocks or struts if needed!

The Warning Signs of Worn Shocks and Struts

While many variables go into the lifespan of your shock absorber or strut (hello, potholes), experiencing any of these seven symptoms means it’s time for a replacement.

• Instability at highway speeds. Your vehicle never feels completely stable on the freeway and is constantly moving up and down. The movement may be slight, but you notice it.
• The vehicle alternately “tilts” sideways. When taking a sharp turn or exit, your vehicle will lean or “tilt” to the outside of the turn and feel wobbly.
• The front dives more than expected under heavy braking. You may not realize this until you have to slam on the brakes hard.
• Rear-end squat during acceleration. You will notice that the front end of your vehicle rises while the rear “squats” under hard acceleration.
• Tires bouncing excessively. After hitting a bump, you may feel a tire (or tires) react or “bounce” for a period of time. You may also hear a rattling noise.
• Unusual tire wear. Because the tire is not held firmly to the road, the tread wears in waves rather than evenly.
• Leaking liquid on the outside of shock absorbers or struts. This is a sign that the seals have broken and are leaking the internal fluids necessary for proper operation.

What Will Happen If I Drive on Worn or Damaged Shocks and Struts

Staying in contact with the road is important, especially when going over bumps or keeping up with highway traffic. Your vehicle’s suspension system, including shock absorbers and struts, is excellent for this task if every part is working properly.

Over time, these parts wear out. You might not even notice it as it gradually breaks down. If they are not working properly, it can affect your control and safety. It can also cause additional wear and tear on other parts of your vehicle, including your tires.

Replacing worn parts before they go bad can help keep your vehicle’s electronic systems and suspension working properly, extend the life of your vehicle – and keep you safer on the road.

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