Sierra 18-1117 Lower Unit Pinion Bearing for Marine Engines

The Sierra 18-1117 is a precision-engineered lower unit pinion bearing designed for marine stern drive and outboard applications. This high-quality replacement bearing supports the pinion end of the driveshaft, allowing the pinion gear to spin smoothly as it transfers power to the propeller shaft.

Key Features:

• Manufactured to meet or exceed OEM specifications for reliable performance
• Compatible with Mercruiser MR, Alpha One, and Gen II stern drive engines
• Fits Johnson/Evinrude outboards, Mercury Marine, OMC stern drives, and Chrysler/Force/US Marine engines
• Direct replacement for multiple OEM part numbers for cross-platform compatibility
• Quality construction ensures proper support and smooth operation of the pinion gear

OEM Cross-Reference Numbers:

• Chrysler/Force/US Marine: 31-F694057, 31-42647A1
• Johnson/Evinrude: 387817, 5007751
• Mercruiser/Mercury: 31-42647A1, 31-42647
• OMC Stern Drive: 387817
• GLM: 21610
• Mallory: 9-75121

Sierra is a trusted name in marine replacement parts, delivering OEM-quality components for professional mechanics and boat owners alike. UPC: 030999974242