Shock absorbers (or struts on most modern vehicles) damp the up-and-down motion of the suspension to keep tyres in contact with the road. They wear out gradually so the deterioration is hard to notice from the driver’s seat – many vehicles have shocks well past their useful life still on the road. Replacement is a moderate DIY job that significantly improves handling, ride comfort, and braking performance.
Shocks vs Struts
Shock absorbers are damping units only – separate components from the springs. Struts combine the damping function with the spring and form a structural part of the suspension (usually MacPherson struts at the front of most modern vehicles). Strut replacement is more involved than shock replacement because you need to compress the spring safely with a spring compressor, or buy preassembled strut units (also called “quick struts” or “loaded struts”) that come with a new spring and top mount already assembled.
Symptoms of Worn Shocks
Vehicle bounces multiple times after hitting a bump (a healthy shock should allow about 1.5 oscillations and then settle). Excessive nose-dive when braking heavily. Body roll in corners that feels worse than you remember. Vague steering and a wandering feeling on the highway. Cupped tyre wear (irregular scalloped wear pattern across the tread). Visible oil leaks on the shock body. Knocking or clunking noises over bumps. The bounce test – push down hard on each corner of the vehicle and release – is a quick check; the corner should rebound and settle without continuing to bounce.
Replacement Procedure
Raise the vehicle and support on jack stands. Remove the wheel for access. The procedure depends on whether you are working on shocks or struts. For rear shocks (typical separate-shock setup), unbolt the upper mount (often inside the boot, under a trim cover, or in the wheel well), then unbolt the lower mount (usually a single bolt through the bottom of the shock to the axle or trailing arm). The shock pulls free.
For struts, the work is more involved. Disconnect the brake hose bracket, sway bar link, and ABS sensor wiring from the strut. Unbolt the lower strut mount from the steering knuckle (usually 2 bolts). Open the bonnet and unbolt the 3 nuts on the upper strut mount inside the engine bay. The strut pulls down and out. If you are reusing the spring (not buying a quick strut assembly), you must safely compress the spring with a quality spring compressor before separating the components – this step is dangerous if done wrong.
Always Replace in Pairs
Always replace shocks or struts in pairs (left and right on the same axle). Replacing only one side leaves the vehicle with mismatched damping that causes uneven handling and accelerated wear of the new component. If both pairs (front and rear) are tired, replacing all four at once is best for ride balance.
Quality Matters
Quality brand shocks (Bilstein, KYB, Monroe, Sachs, Koni) last 60,000 to 100,000 km or more. Cheap unbranded shocks can fail within a year and ride poorly throughout their short life. The labour cost is the same regardless of part quality, so the savings from cheap shocks are short-lived. Match shocks to your vehicle’s intended use – softer comfort-oriented shocks for daily drivers, firmer performance shocks for handling-focused builds, heavy-duty shocks for towing or carrying loads.
Wheel Alignment
Strut replacement disturbs the front suspension geometry, so a wheel alignment is required after the job. Most workshops do a 4-wheel alignment for around A$100 to A$150. Skipping this step causes uneven tyre wear and steering issues.
Shock and strut specifications and torque values are vehicle-specific. MechanicMate offers PDF workshop manuals for over 960 models at mechanicmate.net/shop.
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