Only if it measures outside the manufacturer's tolerance. The gearbox has to come out for a clutch, so that is the time to check the flywheel. If it is within tolerance it goes back on and you keep your money; if it is worn, replacing it in the same visit avoids paying for the gearbox to come out twice.
Why is the flywheel checked during a clutch job?
The dual mass flywheel sits between the engine and the clutch. To replace the clutch the gearbox has to come out, which also gives direct access to the flywheel. That is the one point where it can be measured properly without extra labour.
Because the labour is shared, a DMF is nearly always fitted alongside a clutch kit rather than on its own.
Do you always replace the DMF with the clutch?
No. A DMF is expensive, so we measure before we recommend. We check it against the manufacturer's tolerance with the gearbox out. If it passes, it goes back on. If it does not, we show you the readings before replacing it.
Some garages replace the flywheel as standard on every clutch job. That can be the right call on a badly worn unit, but it should be based on measurement rather than habit.
What are the signs the flywheel is worn?
The classic signs are a rattle or chatter at idle that changes or disappears when you press the clutch pedal, vibration through the floor and pedals when starting or switching off, judder pulling away and a rumble at low revs.
A slipping clutch also generates heat that can crack or blue the flywheel, which is one reason not to leave slipping for long.
What does it cost to do both together?
Combined clutch and DMF replacement on most cars falls between £900 and £1,500 fitted, depending on the vehicle and the cost of the flywheel itself. We give you a fixed price for your exact car before starting.