Description
Mercury 12578T Propeller Shaft Roller Bearing 50-150 HP Gearcase
Replace a worn or damaged propeller shaft roller bearing with the Mercury 12578T bearing, also referenced as 31-12578T. This Mercury roller bearing is used in select 50-150 HP gearcase, propeller shaft, reverse gear, and lower unit applications where this part number is specified.
Key Features
- Genuine Mercury roller bearing for select marine lower unit and gearcase applications
- Commonly referenced as Mercury part number 31-12578T
- Used in select propeller shaft, reverse gear, and gear housing bearing locations
- Supports proper propeller shaft and reverse gear operation inside compatible gearcases
- Important service part for lower unit repair, gearcase rebuilds, and propeller shaft bearing replacement
- Designed for select 50-150 HP Mercury applications when verified by model, serial number, and parts diagram
Fitment / Product Details
- Brand: Mercury
- Part Number: 12578T / 31-12578T
- BU Part ID: Not provided
- Product Type: Propeller Shaft Roller Bearing / Gearcase Bearing
- Application: Select Mercury 50-150 HP gearcase, propeller shaft, reverse gear, and lower unit bearing applications
- Engine Types: Mercury outboard gearcase and lower unit applications where 12578T or 31-12578T is specified
- HP Range: 50-150 HP
- Serial Ranges: Not provided; verify by engine serial number and parts diagram
- Year Range: Not provided; verify by model year, serial number, and service manual
- UPC: Not provided
- Country of Origin: Not provided
- Prop 65: Not provided
- Package Dimensions: Not provided
- Package Weight: Not provided
- Supersedes / Replaces: 31-12578, 12578, F523143
- Fitment Note: Confirm compatibility by Mercury part number, engine model, serial number, gearcase assembly, parts diagram, owner’s manual, or service manual before ordering.
What’s Included
- One Mercury 12578T / 31-12578T propeller shaft roller bearing
Expanded Fitment
- Select Mercury 50 HP outboard gearcase applications
- Select Mercury 60 HP outboard gearcase applications
- Select Mercury 75 HP outboard gearcase applications
- Select Mercury 90 HP outboard gearcase applications
- Select Mercury 115 HP outboard gearcase applications
- Select Mercury 125 HP outboard gearcase applications
- Select Mercury 135 HP outboard gearcase applications
- Select Mercury 150 HP outboard gearcase applications
- Propeller shaft and reverse gear bearing locations where Mercury 12578T or 31-12578T is specified
- Not universal; fitment must be verified by exact gearcase assembly and serial number
Why You Should Buy
- OEM Mercury bearing helps ensure proper fit when matched to the correct gearcase
- Critical component for propeller shaft support inside compatible lower units
- Useful for gearcase rebuilds, lower unit repair, and reverse gear service
- Helps replace worn, noisy, pitted, corroded, or damaged propeller shaft bearing components
- Reliable replacement when servicing by Mercury part number 12578T or 31-12578T
Common Applications
- Propeller shaft roller bearing replacement
- Gearcase bearing service
- Lower unit gearcase rebuilds
- Reverse gear bearing replacement
- Mercury outboard drivetrain repair
- Marine service applications requiring Mercury 31-12578T
FAQ
- What is Mercury 12578T used for? It is a roller bearing used in select Mercury gearcase, propeller shaft, reverse gear, and lower unit applications.
- Is this the same as 31-12578T? Yes, this part is commonly referenced as Mercury 12578T and 31-12578T.
- What horsepower range is this used on? This bearing is used on select 50-150 HP Mercury outboard gearcase applications where the parts diagram specifies 12578T or 31-12578T.
- Does this fit every 50-150 HP Mercury outboard? No. Gearcase designs vary by model, serial range, and configuration. Confirm the exact bearing by part number, model, serial number, and gearcase diagram.
- What part numbers does it replace? Listed replacement or superseded references include 31-12578, 12578, and F523143.
- When should this bearing be replaced? Replace it when the bearing is worn, noisy, pitted, corroded, damaged, or required during lower unit or gearcase rebuild service.
- How do I confirm fitment? Confirm using Mercury part number 12578T or 31-12578T, engine serial number, gearcase assembly, parts diagram, owner’s manual, or service manual.