Hinge Pin Tool – Fits Mercury MerCruiser Alpha One & Bravo Drives (Replaces 91-78310, 18-9861, 90200)
Hinge Pin Tool – Fits Mercury MerCruiser Alpha One & Bravo Drives (Replaces 91-78310, 18-9861, 90200) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
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Hinge Pin Tool – Fits Mercury MerCruiser Alpha One & Bravo Driv...
Hinge Pin Tool – Fits Mercury MerCruiser Alpha One & Bravo Drives (Replaces 91-78310, 18-9861, 90200) is backordered and will ship as soon as it is back in stock.
Product Details
This specialized Hinge Pin Tool is designed for removing and installing hinge pins on Mercury MerCruiser sterndrive bell housings. It is compatible with Alpha One (Gen I & II), Bravo (One, Two, Three), and XR series sterndrive models from 1984 to the current production year.
It serves as a direct replacement for Mercury OEM part 91-78310, Sierra 18-9861, and VG Marine 90200.
- Installation: Designed for manual use with a 1/2-inch square drive or hex interface.
- Material: Constructed from hardened steel with a black oxide coating for superior rust protection.
- Drive Interface: Features a versatile 12-point or hex drive interface for secure engagement.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 91-78310 |
| Sierra | 18-9861 |
| VG Marine | 90200 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This tool fits a wide range of Mercury MerCruiser sterndrive models. Please verify your specific model and serial number range.
| Model | Drive Type | Years | OEM Part No. | Notes |
|---|---|---|---|---|
| ALPHA ONE | Gen I | 1984–1990 | 91-78310 | Sterndrive bell housings |
| ALPHA ONE (GEN.II) | Gen II | 1991-2012+ | 91-78310 | Model code 0L100040 & Up |
| BRAVO | Standard | 0M100001-0W249999 | 91-78310 | Fits all Bravo models |
| BRAVO ONE | Standard | 0F730000-0M100000, 0W250000 & Up | 91-78310 | Fits all Bravo One years |
| BRAVO TWO | Standard | 0F730000-0M100000, 0M100001-0W249999, 0W250000 & Up | 91-78310 | Fits all Bravo Two years |
| BRAVO THREE | Standard | 0F730000-0M100000, 0M100001-0W249999, 0W250000 & Up | 91-78310 | Fits all Bravo Three years |
| BRAVO X ONE | X | 0M100001-0W249999, 0W250000 & Up | 91-78310 | Performance Bravo variant |
| BRAVO X TWO | X | 0M100001-0W249999, 0W250000 & Up | 91-78310 | Performance Bravo variant |
| BRAVO X THREE | X | 0M100001-0W249999, 0W250000 & Up | 91-78310 | Performance Bravo variant |
| BRAVO XR ONE | XR | 0L914990-0W239999, 0W240000 & Up | 91-78310 | High-performance variant |
| BRAVO XR THREE | XR | 0W240000 & Up | 91-78310 | High-performance variant |
| BRAVO XR SPORTMASTER | XR | 0M052945-0M906877, 0M906878 & Up | 91-78310 | Racing/high-performance |
| BRAVO XZ ONE | XZ | 0L914990-0M999999 | 91-78310 | Special performance variant |
| HI PERFORMANCE TRANSOM | - | 0W150003 & Up | 91-78310 | Used on performance models |
| INTEGRATED TRANSOM | - | All-0M052767, 0M052768 & Up | 91-78310 | Used on integrated transom models |
Technical Specs
- Product Type
- Hinge Pin Tool (Special Service Tool)
- Installation
- Manual use
- Housing Material
- Hardened Steel
- Housing Color
- Black
- Coating
- Black Oxide (for rust protection)
- Dimensions
- Length: 2.00 in (50.8 mm), Width: 0.75 in (19.05 mm), Height: 0.75 in (19.05 mm)
- Weight
- 0.13 lb (59 g)
- Drive Interface
- 12-point or hex drive interface
- Warranty
- Varies by manufacturer; 2-year warranty on VG Marine version
What’s in the Box
- 1 x Hinge Pin Tool (Replaces 91-78310)
Installation Notes
This tool facilitates the removal and installation of hinge pins that connect the sterndrive bell housing to the gimbal ring. It is essential for tasks such as servicing bellows, replacing gimbal bearings, working on shift cables, or changing trim senders. In most cases, the trim and tilt sender assembly must be removed before accessing the hinge pins. For stubborn pins, applying heat can aid removal and prevent damage to the tool or housing.
Troubleshooting & FAQ
What is this tool specifically used for?
This is a special service tool for removing and installing the hinge pins on Mercury MerCruiser sterndrive bell housings (port and starboard sides). These pins are the pivot point connecting the bell housing to the gimbal ring, allowing the drive to tilt.
When is this tool necessary?
You will need this tool when performing service that requires separating the bell housing, such as working on bellows, replacing the gimbal bearing, servicing shift cables, or replacing the trim senders.
Can I use a different tool as an alternative?
Some mechanics report success using a standard 1/2-inch hex bit socket. However, this genuine-style tool is specifically designed for the application, providing a better fit and reducing the risk of stripping the pin or damaging surrounding components.
How do I remove a stubborn or corroded hinge pin?
If a hinge pin is seized due to corrosion, applying localized heat to the bell housing around the pin can help break it free. Use caution to avoid damaging nearby components and apply steady, even pressure with the tool.
Is there a quality difference between OEM and aftermarket tools?
Quality of aftermarket tools can vary. The original Mercury tool and high-quality aftermarket versions are made of hardened steel with a black oxide coating for durability and rust prevention. Cheaper alternatives may be made of softer metal and can deform or break under high torque.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns?
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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