Brand new DMF locked – what’s going on here?

Some Dual Mass Flywheels (DMF) originally fitted by Hyundai, Mitsubishi, Nissan, Renault and Volvo are equipped with a locking pin on certain applications. This prevents both masses from being twisted against each other. This simplifies the factory installation process during production and at the same time serves as a kind of transportation lock. 

The locking pin is visible on the rear of the DMF

Workshops often wrongly diagnose the locking of the DMF as a malfunction and have even been known to drill out the locking pin to make the DMF ‘operate normally’.

What should you look out for when you come across a DMF with a locking pin?

The locking pin features a predetermined breaking point that triggers when the vehicle is started for the first time. From this point on, the DMF is fully functional. The fragments of the locking pin remain securely in their original installation location. For the workshop, this means that this DMF can be handled and installed just like conventional versions. 

Any attempt to remove the locking pin should be avoided as this can cause fragments or debris to get inside the DMF, resulting in damage.