How a car’s rear shock absorbers work

what is rear shock absorber

Your car’s rear shock absorbers are an essential part of the vehicle’s suspension system, helping to shield you and your passengers from the discomfort of bumps and potholes in the road, while ensuring that the car handles safely.

Shock absorbers 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. Rear ‘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.

When to change rear shock absorbers

Even if you check your vehicle regularly, chances are that rear shock absorbers won’t be on your maintenance list – and they’re often only inspected at the first signs of trouble. This could be when your car’s handling doesn’t feel right, or you receive a worrying advisory notice on your car’s MOT certificate.

How long should rear shock absorbers last?

A quality pair should last for around five years, but a shock absorber's life is dependent on your style of driving, how often the car is used and how hard it is driven.

Rear shocks wear faster if the vehicle is frequently used to carry heavy loads, or multiple passengers in the back. Plus, the rate of wear 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 shocks.

There are several signs that your rear shocks are worn or failing: you may find that the car is more susceptible to crosswinds or handles badly when cornering. You could experience bouncing or stiffness from your car’s suspension, braking performance can decrease, and uneven tyre wear can be evident.

While uneven tyre wear can be caused by other factors such as poor wheel alignment, it’s worth inspecting the condition of rear 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 replace your rear shock absorbers

A fully functioning pair of rear shock absorbers is vital to ensure that your car handles safely in all conditions. It goes without saying that 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 rear shocks are up to scratch: with the vehicle parked on a hard, level surface, push down hard in turn on each rear wing, taking care to spread your weight and avoid damaging a body panel. 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, carry out a visual inspection. Working in the rear 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 rear shock absorber

Watch this video to see how it's done. Find the full step-by-step task for your model.

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

  1. Loosen the rear wheel bolts
  2. Put the car into gear, chock the front wheels then jack-up the rear 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.
  8. Note: You may be required to compress and remove the coil spring (as shown in this video).

Find the step-by-step procedure for your car at the bottom of this page.

Tools you will need

  • Trolley jack
  • Axle stands
  • Sockets and spanner
  • Torque wrench
  • Coil spring compressor (if necessary)

Parts you will need

  • Rear shock absorbers – note that shock absorbers should be renewed in pairs, to maintain good handling.

How much do new rear shock absorbers cost?

Rear shock absorbers £60-£250
Garage fee savings £100-£200