How a car’s front shock absorber works

Have you ever wondered how a car’s front shock absorbers work? Chances are that you haven’t – until you notice that your car’s handling doesn’t feel right, or you receive a worrying advisory notice on your car’s MOT certificate.

Shock absorbers, a vital part of your car’s suspension system, are hydraulic dampers that absorb the energy created by bumps in the road while driving – safely controlling the movement of the wheels and preventing the car from bouncing as it travels over uneven surfaces.

These clever devices work by converting the kinetic energy received from a shock into heat, which is then allowed to dissipate. Front ‘shocks’ operate with your car’s springs to give a more comfortable ride and ensure the vehicle handles precisely and safely, regardless of the condition of the road surface.

What is the lifespan of your shocks?

Suspension is the key to a comfortable ride, but it’s not just the springs. Your shocks have a lot to do with it, too. As long as they’re happy and healthy that is. How long until they’re not?

It’s easy to think that the hardest working part of any car is the engine, but we’d put it to you that the suspensions should be given some consideration, too. It has to carry the car’s weight, but not just in a simple straight line. No, it has to deal with bumps, twists, turns and varying weights. The suspension is definitely a component of your car that earns its keep.

The suspension consists of two parts. First of all, you have the spring and then you have the shock absorber, or as it’s called in some cases, the strut. Without the shock absorber the car would handle like a waterbed. The springs allow for the car to move, but the shocks keep it all under control. And because they’re working so hard all the time, they wear out.

So how long will they last?

How long should shock absorbers last? A quality pair of shock absorbers should last for around five years, but this is dependent on your style of driving, how often the car is used and how hard it is driven.

The general rule of thumb is that a set of shocks should last for approximately 50,000 miles. Though of course, there are limiting factors at play. The way you drive, the amount of weight you carry, the terrain you drive on – if any of these are adverse, you are going to shorten the life of the shock significantly.

How can I tell if my shocks are past their best?

You’ll feel it in the way the car drives. It will become very bouncy and spongy, and the car will lean (roll) into corners more as the shocks won’t be holding the weight of the car as they once did. You may also hear knocking and banging when you go over bumps, as well as noticing the bumps are more aggressive when you hit them. That’s because the springs aren’t designed to soak up bumps – they’ll simply compress if the shocks have failed.

The two sure-fire signs your shocks have had it are if the car wobbles about if you physically push it down at one corner. The car should bounce straight back up and stay. If it wobbles about the shocks aren’t doing anything. The other thing to do is look at them. If they look wet, this is a sign the oil within them is leaking past the internal seals. No fluid means no ability to absorb those shocks.

When to change your shock absorbers

When you need to change your shocks will also be influenced by the state of the roads; surfaces riddled with craters, potholes and speed bumps will eventually lead to premature wear and possible failure of the front shocks. There are several signs that your front shocks are worn or failing: you may find that the car is nose-diving or swerving when you brake, is more susceptible to crosswinds or handles badly when cornering.

Stopping distances can become longer and you’ll notice more vibration through the car’s steering, particularly at speed. You could experience bouncing or stiffness from your car’s suspension, and uneven tyre wear can also result from worn shock absorbers.

While uneven tyre wear can be caused by other factors such as poor wheel alignment, it’s worth inspecting the condition of your front shocks a couple of times a year – any signs of ‘misting’ (a slight oil leak from the shocks) is a sign that they’re on the way out; a defect that can lead to an MOT advisory or failure.

Why you should change your shock absorbers

A fully-functioning pair of front shock absorbers is vital to ensure that your car handles safely in all conditions. It goes without saying that longer braking distances and sloppy cornering ability could lead to an accident, particularly in wet weather.

There is a simple test that can be carried out to determine if your front shocks are up to scratch: with the vehicle parked on a hard, level surface, push down hard in turn on each front wing.

A functional shock absorber will quickly compress and rebound – but a shock that’s worn or failed may bounce several times before it settles. Even if the shock passes the bounce test, it’s worth carrying out a visual inspection.

Working in the wheel arch section, use a torch and look up deep along the length of the shock absorber for signs of oil leaks – a tell-tale sign that replacement may be needed.

How to change a shock absorber

This is a clip from a sample video. A very brief summary of the task:

  1. Loosen the wheel bolts
  2. Open the bonnet then jack-up the front of the car and support it on axle stands.
  3. Remove the wheel
  4. Remove the shock absorber top mounting nut/bolt(s).
  5. Loosen and remove the mounting bolt(s) at the bottom of the shock absorber.
  6. Remove the shock absorber from the wheel arch.
  7. Fitting is a reverse of removal, making sure you tighten the mounting nut/bolt(s) to the specified torque rating.

Tools you will need

  • Trolley jack
  • Axle stands
  • Sockets and spanner
  • Torque wrench

Parts you will need

Front shock absorbers. Try to buy the best quality that you can afford. Note that shock absorbers should be renewed in pairs, to maintain good handling.

How much do new front shock absorbers cost?

Front shock absorbers (each) £60-£250
Garage fee savings £100-£250