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How can I tell if my shock absorbers need replacing?

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Updated 2 Oct 2020

Rachel White

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When our ancient ancestors invented the wheel, they didn’t envision the suspension system that needed to go with it. Consequently, the early days of suspending a carriage above a simple axle and wheel design was ingenious but extremely uncomfortable.

Things did evolve, of course, but things remained fairly primitive and chains and straps were used as a suspension system until the early 1900s. Development moved swiftly from there with the arrival of the leaf spring and, in the mid-1900s, elliptical springs.

Move forward to today and suspension systems are extremely advanced, using a variety of components to deliver a smoother and ever more comfortable driving experience.

The shock absorber is central to the delivery of this improved ride quality and vehicle handling.

How does a shock absorber work?

The suspension system as a whole works as a cohesive unit, with each component supporting and complementing the others.

As a car moves over a bump or dip in the road, the springs of the suspension system compress to absorb the blow. With the bump or dip navigated, the compressed spring releases the energy it contains under compression and return to its original form. If there were no way of controlling this energy and the spring was the only component of the suspension system, then a car would effectively bounce its way along the road as the spring continually compresses and expands.

This is where the shock absorbers come in. They are mounted alongside (or inside) the springs and their job is to absorb some of the springs’ energy.
Inside the shock absorber there’s a piston that moves inside an oil-filled tube. As the piston moves with the up and down movement of the car, the oil acts to dampen the severity of the action of the springs by providing resistance against the moving piston. Holes and valves within the piston allow for the control of the amount of this resistance.

Optimal compression and rebound valving are incorporated to provide not only the most favourable handling conditions but also to reduce aeration and foaming inside the unit, which can lead to shock absorber fade.

What happens when a shock absorber fails?

A shock absorber is constantly moving and eventually, the internal seals and valves will wear causing internal failure or even external fluid leaks. If a shock absorber loses fluid, gas or pressure, its function will be compromised.

BAD SHOCKS Are they safe?

If there is external damage to a shock absorber this can create problems on the inside. The issues may not be apparent from looking at the shock absorber as a small dent may seem harmless. However, there may be internal damage and you will soon notice the signs if there is.

A well-made shock absorber has a generous lifespan if treated well. If you do a lot of off-road driving, then your shocks are working harder and may not last as long as those used for highway driving. Generally, a vehicle will require at least one or two sets of shock absorber changes in its lifetime.

Symptoms a shock absorber needs replacing

  • Vibration or rough ride
  • Shock absorber is leaking fluid
  • Uneven tyre wear
  • Nose diving on braking
  • Car rocking on cornering or in high wind
  • Longer braking time
  • Damaged shock absorber
  • Bottoming out on road

If you have noticed any of the signs of a failing shock absorber it’s time to get them checked by an awesome AutoGuru suspension expert.

If you’re wondering how much shock absorbers cost to replace check out this shock absorber replacement article.

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Written By

Rachel White

Rachel spent her early adult life around cars, motorsport and hands-on with her own cars. This interest moved into various careers within the Automotive industry. Joined with her passion for writing, Rachel loves putting the two together to share her experience, so we can all become AutoGuru’s.