Car Shock Absorbers: What You Need to Know

Shock absorbers are an important part of your car's suspension system as they work to absorb the impact as you drive over uneven surfaces. By properly absorbing bumps and vibrations from the road, your car's shock absorbers and suspension system ensure a comfortable and safe ride for you and your passengers. That's why it's crucial to know how to look out for signs that your shock absorbers may be worn out and need to be replaced.

Things to Know About Your Shock Absorbers

When people talk about car suspension, they are usually referring to shock absorbers. In the most basic terms, a shock absorber, or damper, is a tube containing a piston, hydraulic fluid, and occasionally high-pressure gas.  These components work together to ensure a smooth ride, among other things.  Below are some things you should know about shock absorbers.

Function of a shock absorber

Shock absorbers absorb vibrations and control the up/down movement of shock absorber springs. When the car's wheel hits a bump, the fluid dampens the impact on the piston and reduces the movement of the piston and spring as they return to their position. This is important because:

• Ensures that the tyre is always in contact with the road surface.
• Provides optimum braking performance.
• Prevents vehicle from bouncing or swinging excessively.
• Ensures optimal steering response.
• It ensures a smooth, comfortable and safe ride.

How long do shock absorbers last?

Like any part of your car, shock absorbers are subject to fatigue and wear. Therefore, it is always important to pay attention to your ride quality and have your shock absorbers checked regularly. The lifespan of a shock absorber depends on several factors, including the mileage of your car, your driving style, road conditions, and more. But generally speaking, shock absorbers are considered consumables, just like the tires and brake pads on your car. Therefore, it is a good idea to have them looked at around the 30.000-mile mark and replace them at 50.000 miles.

Types of car shock absorbers

The two main types of shock absorbers on the market are oil-hydraulic shock absorbers and gas-charged shock absorbers.

1. Hydraulic shock absorbers

A hydraulic shock absorber comprises a working cylinder or tube, a compression chamber containing air, and a piston rod that directs the hydraulic fluid (oil).  It provides good performance on asphalt roads and under normal driving conditions, making it suitable for ordinary passenger cars.  On rough surfaces and during prolonged aggressive riding, the oil in the shock absorber can begin to boil and form bubbles called cavitation.  Cavitation causes the viscosity of the hydraulic fluid to change, reducing the performance of the absorber.

1. Gas shock absorbers

A gas shock absorber has the same structure as a regular hydraulic one but has pressurized nitrogen gas instead of air in the gas chamber.  Nitrogen gas compresses the oil, preventing cavitation, foaming and bubble formation, ensuring more consistent performance.  Gas shock absorbers are suitable for heavy and commercial vehicles, as well as sports cars that require agile steering at high speeds.

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6 Signs of a Worn or Bad Shock Absorber

A worn shock absorber will not only cause a harsh and uncomfortable ride, but will also negatively affect the vehicle's handling and braking performance. It may also cause premature wear of other components such as tires and brakes.  Here are signs you may have worn out shock absorbers.

1. Vibrating steering wheel

It is normal for the steering wheel to vibrate when you drive over potholes or uneven surfaces. However, excessive vibrations are a sign that the shock absorbers are worn out and cannot dampen the vibrations well enough. If the steering wheel vibrates even on a smooth, level road, the shock absorber may be significantly worn or damaged.

In addition to uneven surfaces, you may also experience excessive vibrations while driving on the highway at high speeds. Having to control a vibrating steering wheel is not only uncomfortable, but it can limit your ability to steer your vehicle which could cause an accident.

1. Your vehicle shakes or sways while driving

With worn shock absorbers, the shocks and vibrations that your tire absorbs will also be transferred to the entire vehicle.  As a result, your car may vibrate, bounce, or sway excessively, making it feel unstable on the road.  This problem usually intensifies when driving at high speeds.  If your shock absorbers are badly worn, your car may bottom out when driving over bumps and dips which can further damage your suspension system.

1. Your vehicle rolls or sways excessively in corners

One function of shock absorbers is to ensure that the car body remains in a neutral position when cornering.  If you have a worn or faulty shock absorber, it can lose its ability to control the rate of weight transfer when the car is cornering.  This will increase body roll when cornering, especially at high speeds.  It may also result in your car needing more steering input even when turning at low speeds.

1. Uneven tire wear

When your car bounces due to worn shock absorbers, it can put more pressure on your tires and accelerate wear.  A common type of tire wear caused by worn absorbers is cupping or scalloping. This refers to when you have high and low tread wear in random places.

Worn parts are typically three to four inches in diameter and can cause a rumbling sound at high speeds or a harsh ride at lower speeds.  If you notice your tires becoming warped or flaking, be sure to have your shock absorbers checked immediately.

1. Excessive nose dip and squat

Properly functioning shock absorbers stabilize the movement of the suspension when braking and accelerating.  When your shock absorbers are worn out, the front of your car may dive when braking and the rear may squat when accelerating. This is a serious problem as it can increase your stopping distance and place excessive load on other suspension components.

While it is not recommended to test drive it, you can pay attention to how your car reacts under heavy acceleration and braking the next time you drive.  Alternatively, you can push hard on the sides of your car.  If it bounces several times before stopping, it is a sign of worn shock absorbers.

1. Fluid leak on shock absorbers

A sure sign of a bad or worn shock absorber is when it leaks fluid.  If the seal is worn, hydraulic fluid may leak out and reduce shock absorber performance.  Dirt can also get into the tube and affect the piston's ability to move as intended.

When replacing faulty shock absorbers, it is advisable to also check the condition of the coil springs.  If the spring has changed shape or lost its elasticity, you should replace it.

How to replace shock absorbers

If you notice any reason to replace your shock absorbers, here are 11 steps to take.

1. Park the vehicle on a level surface and block the wheels, which will remain on the ground.  Using a floor jack, raise the vehicle and secure it with jack stands.  If possible, leave the wheels on the vehicle for added safety.  Make sure you place the stands in the right spots on the frame for stability!
2. Loosen the lower shock absorber retaining nut, but do not remove the bolt at this time.  The nuts on the shock absorber bolts may be rusted and/or difficult to remove.  Use a little penetrating oil, like PB B'laster, and let it work to dissolve them.  You can also use a nut splitter to help remove stubborn nuts.
3. Locate the mounting/securing hardware at the top of the shock absorber.  Depending on the type of shock, it may be held in by two bolts that require a long extension for access.
4. Remove the two fixing bolts.  Shock absorbers can be held in place by a single stud/nut on the top of the shock absorber or by a through bolt.
5. Finish removing the nut and tap the lower shock absorber bolt using a rubber mallet.
6. Remove the old shock.
7. Install the new shock absorber by inserting the lower bolt first.  Tighten the nut by hand.
8. Once the bottom bolt is in place, use the utility knife to carefully cut the shock compression strap.  The shock absorber is under pressure and as soon as the belt is cut, it will slowly expand.  As you do this, be ready to insert the bolt(s) into the top of the shock absorber and the mounting hardware.
9. Tighten the nuts on the upper and lower bolts to the correct specifications.
10. It is always recommended to replace shock absorbers in pairs, so once you are finished with the first one, repeat the process on the second shock absorber.
11. After double-checking the torque on all fasteners, go out for a test drive.  You will enjoy the best ride quality!

PRO TIP

You will need an alignment after replacing the struts, but not the shock absorbers.  This is because struts are an integral part of your steering and suspension system, while shock absorbers are not.