90518-ZW1-003 Gear Shim - Overview. The 90518-ZW1-003 Gear Shim is a critical component in Honda marine engine systems. It is a thin metal washer designed to precisely adjust the meshing of gears within the marine propulsion system. By fine-tuning the distance between gear teeth, it ensures optimal gear engagement, which is vital for efficient power transfer and the longevity of the gearbox. This shim guarantees seamless integration with existing parts, maintaining optimal performance and durabi