Security enhancements made to comply with Thatcham requirements for high-security locks have driven the need for a free-wheeling lock cylinder. GM-49753 is required to properly retain the free-wheeling door lock cylinder drum during assembly of the lock cylinder drum retaining pin. This procedure is done each time a door lock is replaced, as the cylinder is serviced as a disassembled kit.
The lock cylinder is inserted into GM-49753, then assembled into a vice. Once secured, a hammer and drift punch are used to remove or install the retaining pin. Attempts to service the lock cylinder core retaining pin without GM-49753 may result in damage/breakage to the lock cylinder.