Yamaha 90179-34304-00 Middle Drive Gear Special Shape Nut

The Yamaha 90179-34304-00 Middle Drive Gear Special Shape Nut is a genuine Yamaha locking nut designed to secure middle drive gear components in shaft-drive Yamaha motorcycles. It is typically installed in the middle gear housing of shaft-drive systems such as the XJ650 and XJ750, where it helps retain gears, cams, or shafts under rotational load in the engine drivetrain assembly. Designed with a flanged, special-shape profile for locking and torque retention, this nut serves as an OEM replacement during drivetrain servicing and repair. Key specifications include Brand: Yamaha; Part Number: 90179-34304-00; Product Type: Special Shape Nut / Locking Nut; System Type: Shaft drive / middle gear drivetrain assembly; Application Area: Engine drivetrain housing; Compatibility: Yamaha XJ650, XJ750, and similar shaft-drive motorcycles; Availability: Genuine Yamaha part and may be discontinued or limited supply; Common replacements include Yamaha 90179-14317-00, 90179-12323-00, and 90179-25495-00.