Shocks and Struts: What You Need to Know

The essential job of your suspension system is two-fold. One, to keep the tires in as much contact as possible with the road under bumps, dips, and G-forces pulling the car side to side in cornering, and front to back in stopping and acceleration. The second, to give the passengers a comfortable, smooth ride on the road. Suspension systems date as far back as the horse and carriage, but through the invention of the internal combustion engine and more speed, suspension systems became more and more advanced as the years went by. Couple this with faster cars, faster roads, and more powerful engines, and the need to engineer better, more responsive suspension was always present. While power is important (and people are generally very fond of it), so is control - it keeps you comfortable and safe. Your suspension system gives you the control necessary to handle the high horsepower of your vehicle, and provide you with a comfortable ride.

Cars with poor or failing suspension systems maximize the impact of every bump and pothole in the road, which is uncomfortable, and can cause damage to other parts of the car. Meanwhile, a well-calibrated suspension system ensures that the ride is smooth and control at all times is top-notch.

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What is the Suspension on Your Car?

Any suspension system starts with tires. Your tires are the point of contact between the car and the road, and having tires with appropriate tread ensures that this connection remains constant. Your tires allow you to accelerate, decelerate, and turn smoothly. Your tires, wheels, braking system, and axles are known as “unsprung weight” as these are the only components on the car that are not held up by the suspension system’s springs. Tires also can absorb a little bit of the impact of road irregularities, but they cannot handle these alone.

The tires work together with the springs in the 4 corners of your vehicle to handle these irregularities. They handle not only the weight of the vehicle and it’s passengers above them, but also keep the unsprung weight under control below it. These springs are connected to various components, such as control arms to pivot, turn, and correct – to keep the car heading straight when you want to, and to turn when you want to. The problem with any spring is for every reaction, there is an equal and opposite reaction – meaning, if a spring is compressed during a bump, there will be an equal spring-back reaction, just like a bouncing ball. Without the presence of a damper, or shock absorber, the spring would continue to vibrate and these reactions would spiral out of control. This is where a shock, or strut assembly comes into play.

What is the Difference Between Shocks and Struts?

The shock energy from a bump or a rock travels through the spring, and it’s the shock or strut’s job to dampen this reaction. Think about slamming a basketball down on the pavement. The ball has no dampening, and immediately rebounds, with equal force of when you slammed it down. Now, take that same basketball and slam it down into a swimming pool. The ball doesn’t bounce because the water in the pool is acting as the damper. You are allowed to slam the ball down (the spring compressing), but the rebound of the ball has been dampened. All of these suspension components – the springs, control arms, ball joints, shocks and struts all work in tandem, and often times people refer to shocks and struts as simply “shocks”. That said, they are designed somewhat differently.

What are Shocks?

Shock absorbers, as stated before, act as a spring damper. Their sole purpose is to travel with the spring, or nearby, and dampen its rebound so the car doesn’t bounce, and stays stable, straight, and glued to the road. They themselves do not support any of the weight of the vehicle as the spring does. Shocks help you absorb and disseminate the energy caused by driving over road irregularities.

What Happens when a Shock Absorber Fails?

When a shock fails, that corner of the car will become extremely unstable. You’ve probably seen a car on the road that you’re following, and the rear axle is vibrating up and down rapidly even though the car doesn’t appear to be going over any bumps – this is what a pair of failed rear shocks look like. When a front shock fails, you generally have massive tire hop, and feel this all the way through the steering wheel. In the rear, the car can also feel loose when going over bumps, almost like the rear end of the car is about to kick out, from side to side, or just doesn’t feel stable. Couple this with winter driving, and you have a recipe for an unstable car spinning out.

What are Struts?

Struts are an essential structural part of your suspension system as not only are they a shock absorber, but they also house and hold the spring for that side of the car, and function as the upper-link to the body in most systems. Your struts support the actual weight of the vehicle itself, so there are more components in a strut assembly. These assemblies are absolutely essential to steering and movement because they help to maintain the alignment of your car, and the steering ability of your car. Struts can have a coil-type spring, or an airbag spring on them, and generally also have an upper mount and bearing that bears the weight, and turning ability of the car. Here, multiple things on a strut could fail – not only the shock absorber, but the coil spring or upper mount can fail as well. A failed strut will and can be much more detrimental to the driving ability of the car than a shock absorber can.

When Should I Replace Shocks and Struts?

As with any other component on your automobile, the actual requirements vary depending on the conditions in which you drive your vehicle and also the make and model of the vehicle itself. A very general thought is that most shocks and/or struts will need replacing on a car between 60-100,000 miles of driving or 6-8 years. However, there are many mitigating factors that may extend or shorten the life of your shocks and your struts. Particularly if you are driving on bumpy roads often, such as dirt roads or cobblestone roads, you may need to get your shocks and struts replaced more often as compared to individuals who generally drive on smooth pavement or do lots of highway driving.

Getting your shocks and struts checked should be part of a yearly tune up done on your automobile. This helps you get a better sense of when these parts are wearing down on your vehicle and need to be replaced.

Signs it’s Time to Replace

There are many signs that your shocks or struts may need to be inspected and potentially changed. If you notice that your vehicle is responding poorly to your steering input, seems to not rebound and stabilize quickly after bumps, or just doesn’t feel the same going over them, you probably need to have your shocks and struts checked. Any pops, clicks, or noises going over bumps at speed, or speed bumps are also a tell-tale sign that something may be wrong. Stiff steering or noises when turning can also be a sign that there is a problem with your suspension system and possibly the shocks and struts, but may also be in the steering system itself. Unstable braking may indicate an issue with these components as your shocks and struts also stabilize forward and backward forces.

Doing a DIY visual inspection of your shocks and struts is not very difficult. Typically, when these components start to break down, they start to leak. If you notice any wetness or oily liquid near the shock body, it needs to be checked out. If you notice that your shocks and struts are wearing out, it is also important to pay attention to your tires. Particularly if your struts are wearing out, your tires can wear uneven, as generally the car is not staying in proper contact with the road, or has fallen out of alignment.

How Much Do Shocks and Struts Cost to Replace?

In terms of shocks and struts replacement cost, it generally is cheaper and easier to replace shocks than struts. Many people choose to replace their own shocks, given that the shocks are not a structural part of a car’s suspension system, and thus replacing them doesn’t require complicated procedures like compressing coil springs. In recent years, pre-assembled “loaded” struts have become extremely popular, as these items incorporate the complete package – the strut, spring, and mount ready to bolt right in, and make the job much, much easier. It is generally advisable though to get struts replaced professionally, since changing out the struts tends to be more complicated. That doesn’t mean that DIY strut jobs are unrealistic though and the job can be tackled at home with the right amount of preparation.

If you’re unsure, seek out one of our preferred installers to help do the job. Remember, after any strut change, the vehicle’s alignment will be compromised, and you will need to get the vehicle in as soon as possible to have a proper alignment done and set on the vehicle. You can get the parts you need at your local AutoZone Store.

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