MacPherson Strut
Spring, damper and steering pivot in one
The MacPherson strut is the front suspension of most cars on the road. It stacks the coil spring around a telescopic damper and uses the whole assembly as a structural member: it locates the wheel, carries the car’s weight, absorbs bumps, and even acts as the steering pivot.
What it does
Supports the car’s weight, absorbs road impacts, controls body motion and provides the upper steering pivot.
Above each front wheel, reaching up into the strut tower under the hood.
How it works
- The coil spring carries the car’s weight and compresses over bumps, storing the impact as spring energy.
- Without damping the spring would bounce for seconds — the damper inside converts that motion to heat by forcing oil through small valves in its piston.
- Compression damping is light (let the wheel ride over the bump); rebound damping is firmer (release the stored energy slowly).
- The top mount contains a bearing so the whole strut rotates when you steer.
- The bottom clamps rigidly to the wheel knuckle, so the strut also resists braking and cornering loads.
Key numbers
| Spring rate | 20 – 60 N/mm typical |
| Damper type | Twin-tube or monotube, gas-charged |
| Wheel travel | ~150 – 200 mm |
| Service life | ~80,000 – 150,000 km |
Warning signs of trouble
- Car keeps bouncing after a bump — worn damper.
- Cupped, unevenly worn tires — the wheel is hopping on the road.
- Clunks over bumps — worn top mount or loose hardware.
- Oil streaks down the strut body — blown damper seal.
Maintenance & care
- Replace struts in pairs (both fronts or both rears).
- Get an alignment after any strut work.
- Inspect top mounts and bump stops when replacing.
Frequently asked questions
What does the macpherson strut do?
Supports the car’s weight, absorbs road impacts, controls body motion and provides the upper steering pivot.
How does a macpherson strut work?
The MacPherson strut is the front suspension of most cars on the road. It stacks the coil spring around a telescopic damper and uses the whole assembly as a structural member: it locates the wheel, carries the car’s weight, absorbs bumps, and even acts as the steering pivot.
What are the signs of a failing macpherson strut?
Car keeps bouncing after a bump — worn damper. Cupped, unevenly worn tires — the wheel is hopping on the road. Clunks over bumps — worn top mount or loose hardware. Oil streaks down the strut body — blown damper seal.
How do you maintain a macpherson strut?
Replace struts in pairs (both fronts or both rears). Get an alignment after any strut work. Inspect top mounts and bump stops when replacing.