What is a Dual-Mass Flywheel (DMF)?
A heavy clutch component that smooths out engine vibration on its way to the gearbox.
Simplified animation — not to scale.
In plain English
A dual-mass flywheel is a two-part flywheel bolted between the engine and the clutch. Two heavy discs are joined by internal springs, so the engine side can rotate slightly independently of the gearbox side, soaking up the pulses of each cylinder firing.
"Like the shock absorber in a tow bar — it's there so every jolt from the engine doesn't jab the gearbox in the ribs."
How it works
Modern diesels and some petrols produce strong torque pulses that would otherwise rattle through the gearbox. The DMF's internal springs flex on every firing pulse, isolating the gearbox from those shocks. Over time the springs and friction surfaces wear, the two halves develop play, and the whole assembly starts to clatter.
Signs of trouble
- ⚠Rattling or clattering at idle that quietens with the clutch pressed
- ⚠Heavy vibration when pulling away
- ⚠Juddering through the clutch pedal
- ⚠A burning smell after stop-start driving
- ⚠Clutch slipping or "graunching" between gears
£900 – £1,800 fitted with clutch
Always get a written quote. Prices vary by car, region, and parts brand.