The importance of checking your flywheel

In most commercial vehicle engines, the flywheel is a massive component, and despite its size, it can wear out, especially in areas  such as the starter gear ring or the friction surface.

The commercial vehicle experts at ZF Aftermarket recommend careful checking of the flywheel when changing the clutch, and to be on the safe side, replace the flywheel at the same time.

After a clutch change on a truck, if the clutch engagement is still jerky at takeoff, it may be because the flywheel is worn. Although this component is extremely durable and therefore not included in the usual clutch spare parts kits, it is subject to wear and tear over time.

The friction surface, for example, has a conicity that is barely visible to the naked eye, tapered by just a few tenths of a millimetre so that the friction disc does not abruptly apply, making start-up as smooth as possible. However, this taper can wear out over time and if this happens, the frictional connection is established without transition when the clutch is engaged, which leads to jerky starting, as described above.

The jerky starting is not just a comfort issue – it can also result in damage to the driveline.

The ZF experts also say that another point on the flywheel that’s subject to wear is the starter ring gear. The engine is likely to be started several thousand times during its service life meaning that the starter pinion meshes with the ring gear frequently, wearing away the hardened steel and resulting in starting problems. Other criteria for assessing the condition of a single-mass flywheel are local thermal overloads or cracks in the contact surface.

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The guys at ZF, therefore recommend that commercial vehicle workshops thoroughly inspect the vehicle's flywheel every time the clutch is changed. If there are any signs of wear it is suggested that it is replaced at an early stage, or at the same time as the clutch. Replacing the component does not necessarily incur high additional costs, but can prevent expensive damage further down the track.

ZF Aftermarket says that it offers an extensive product range of flywheels for trucks and buses from virtually all well-known vehicle manufacturers under its SACHS brand, available from ZF in Oceania.

For further information on ZF in Oceania, and its brands and services, click here or call 1800 ZF SALES (1800 93 72537).