Flywheels, The Design, The Purpose, The Dangers

To ensure that the engine runs evenly, a large moulding body the flywheel is attached to the crankshaft. It stores kinetic energy temporarily and releases it again evenly. A ring gear is attached to the flywheel for starting the engine. A side of the flywheel forms the friction couple surface with the clutch disk. In the centre of the flywheel is the pilot bearing for the transmission shaft.

Dual Mass Flywheel

Particularly at low speeds, the unavoidable vibrations caused in a vehicle are detected mainly as rattling and humming. Manufacturers developed the dual mass flywheel as a completely technical innovation to combat these symptoms. Today, it is used in one in every four European vehicles and more than 20 vehicle manufacturers.
The dual mass flywheel fulfils two tasks. It holds the gear ring for starting the engine and damps the entire drive chain. The disc flywheel is separated into two masses which can be turned against each other up to 120% via a bearing. The two decoupled masses are connected via an efficient damping spring system. This not only helps to avoid noise, but also enables comfortable driving at low speeds in order to reduce fuel consumption.

Damped Flywheel Clutch (DFC)

The DFC is an upgrade of the dual mass flywheel. The clutch disc, clutch assembly and the crankshaft screws are already built in. All this combined creates an extremely compact module, which makes assembly significantly easier.

Be warned- Replacing incorrect flywheels will cost in the long run

While every repairer wants to do the best for their customers, including reducing the cost of drivetrain component replacements, Manufactures warn of a worrying trend taking place with the incorrect replacement of original equipment specification dual mass flywheels with lower cost and incompatible solid flywheels.

While the difference is not noticeable on some vehicles, the finely tuned variation in harmonics balance between the engine and gearbox is completely lost by this practice. This leads to the eventual wearing of gears to more expensive major drivetrain problems over the long term.

There is no advantage to fitting a solid flywheel in the place of a dual mass flywheel which was invented by for the very purpose of achieving total balance between the engine and gearbox harmonics. While more expensive than solid flywheels, the long term cost of replacing the correct component far outweighs the labour and component costs of returned customers along with the greater problems that this practice can cause down the track.

One of the biggest problems with replacing a dual mass flywheel incorrectly with a lower cost solid flywheel is that in most cases there is no audible difference or vibration change. The harmonics involved cannot be sensed by the driver. But in time expensive gear replacements may need to be made.

Here at A1 Clutches we always recommend fitting OE parts according to manufacturer’s guidelines.