It is urgently advisable to check clutch disks for lateral run-out before they are installed in the vehicle. The clutch disk is the component that makes the connection in the center of the clutch. It is a compact, very complicated component which is subjected to heavy loads. Together with the clutch pressure plate, it transfers engine torque to the transmission input shaft. It also reduces the torsional oscillations caused in the transmission by the combustion engine.

ZF checks each individual clutch disk after production for freedom of movement and only releases the clutch disks for sale which have passed the check: As part of this process, ZF employees lay the clutch disks between two plates which are pressed together with a defined force. The plates are then separated by a certain distance. If the clutch disk is adjusted correctly, it will be able to rotate freely between the plates.

In order to function optimally, new clutch disks should not exceed a maximum lateral run-out of 0.5 millimeters.

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Before installing the clutch disk, the lateral run-out must be checked and corrected if necessary.

Checking clutch disks in the workshop ensures perfect functioning.


Despite impeccable manufacturing and checking by ZF, there is a risk that products can be damaged during transport, handling or storage. This makes it advisable to inspect each clutch disk for lateral run-out prior to installation – using a special tool (dial gage) in the outer third of the clutch facing. If the measured deviation exceeds 0.5 millimeters, the clutch disk must be corrected using a straightening device. Otherwise there is a danger that the clutch will not separate correctly later.

The best alternative is checking the clutch disk


Workshop employees who know how to check clutch disks do not have to spend much time on the lateral runout check, especially compared to the time it would take to dismount the transmission, which would otherwise be necessary. This means checking is the best as well as the most cost-effective method.

For workshop employees, a lateral run-out check is not time-consuming.