A strut is a suspension component that does double duty. It contains a shock absorber inside, but unlike a plain shock, it is also a structural part of the suspension that holds the wheel in place and often carries the coil spring. Most front-wheel-drive cars use MacPherson struts because they are compact and light. Because a strut is load-bearing, a worn one affects not just ride comfort but also alignment and steering.
Animated: how a Strut actually works
🔧 How It Works, Step by Step
1
Strut supports the corner
The strut mounts between the steering knuckle below and the body above, carrying the car's weight.
2
Spring absorbs the bump
A coil spring seated on the strut compresses to soak up road impacts.
3
Internal damper resists bounce
The shock absorber built into the strut controls the spring's motion so the wheel settles.
4
Strut guides steering
The strut pivots on its top mount, becoming part of the steering axis as you turn.
5
Wheel stays located
As a structural member, the strut keeps the wheel aligned through its full travel.
🧩 The Key Parts
Damper cartridge
The shock absorber inside the strut that controls motion.
Coil spring
Seated on the strut to support weight and absorb bumps.
Strut mount
The top bearing and mount that lets the strut pivot for steering.
Strut body
The structural housing that locates the wheel and bears the load.
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🩺 Signs of a Failing Strut
Clunking over bumps from the top mount
Excessive bouncing after a dip
Uneven or cupped tire wear
Nose diving under braking
Steering feels loose or wanders
⚠️ Common Problems
Worn damper
The internal shock loses its ability to control motion, so the car bounces and tire grip drops.
Failed strut mount
A worn top mount or bearing causes clunks and can make steering notchy or noisy.
Leaking fluid
Oil seeping from the strut body signals a failed seal and lost damping.
💰 Cost to Fix
$400-$900 per axletypical range to repair or replace, parts and labor
❓ FAQ
What is the difference between a strut and a shock?
A shock only damps motion, while a strut also holds the wheel in place structurally and usually carries the spring and steering pivot.
Should struts be replaced in pairs?
Yes. Replacing both struts on an axle keeps the ride balanced and handling even side to side.
Do I need an alignment after replacing struts?
Usually yes, because the strut is part of the steering and alignment geometry, so replacing it disturbs the settings.
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