Shock absorbers (or struts on most modern vehicles) damp suspension oscillation – they prevent the springs from continuing to bounce after hitting a bump. When they wear out, ride quality deteriorates, handling becomes vague and unpredictable, tyres wear unevenly, and braking distances increase significantly. Replacement is a moderate DIY job that pays back in better handling and safety.
Symptoms of Worn Shocks or Struts
Excessive bouncing after hitting a bump (the classic test – push down on a corner of the vehicle, release, and the body should settle within one or two oscillations), nose-dive under braking, body roll in corners, vague or floaty steering feel especially at highway speed, cupped or scalloped tyre wear, visible oil leaking from the shock body, and clunking noises from the suspension over bumps. Many vehicles fail roadworthy inspection on shock condition alone.
Strut vs Shock Replacement
Most modern vehicles use MacPherson struts at the front – the strut is a structural part of the suspension, holding the wheel upright and incorporating the spring. Strut replacement requires either a spring compressor (to safely remove and reinstall the spring) or a complete strut assembly (the simpler option – the spring, strut, and top mount come pre-assembled). Loaded strut assemblies cost more but eliminate the need for a spring compressor and the risk of working with compressed springs.
Rear shocks on many vehicles are simpler – they bolt to the body at the top and to a lower control arm at the bottom. No spring is involved (the rear coil spring sits separately). Rear shock replacement on these vehicles takes 30 minutes per side once the wheel is off.
Front Strut Replacement Procedure
Loosen the wheel nuts, raise the vehicle and support on jack stands, remove the wheel. Disconnect any sway bar links, ABS sensor brackets, and brake hose clips attached to the strut. Remove the bolts holding the strut to the steering knuckle (typically two large bolts). Open the bonnet and remove the three top mount nuts on the strut tower. Lower the strut and knuckle assembly out from the wheel arch. Transfer the spring, top mount, and bump stop to the new strut using a spring compressor (or simply install a complete loaded assembly). Reinstall in reverse order, torque to specification, and have a wheel alignment done immediately afterwards.
Always Replace in Pairs
Always replace shocks in pairs (both fronts together, both rears together). Replacing only one side creates a left-right imbalance in damping characteristics that affects handling, especially in emergency manoeuvres. The price difference between buying one shock and a pair is usually small.
Safety Warning on Spring Compressors
A compressed coil spring stores enormous energy – if the compressor slips, the spring can launch with deadly force. Use only quality spring compressors in good condition, ensure the hooks fully engage at least 4 coils, and never work with the spring under load anywhere near other people. Many home mechanics simply pay a workshop to swap springs onto new struts to avoid the risk – it is a cheap service.
For specific torque values, sequences, and component diagrams, MechanicMate offers PDF workshop manuals for over 960 models at mechanicmate.net/shop.
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