Hinge Pin Tool – Fits Mercury/MerCruiser Sterndrive Alpha 1 Gen 1 & 2, Bravo I II III (Replaces 91-78310)

Hinge Pin Tool – Fits Mercury/MerCruiser Sterndrive Alpha 1 Gen 1 & 2, Bravo I II III

This is a specialized service tool designed to remove and install hinge pins in Mercury MerCruiser sterndrive units. It is compatible with a wide range of drives, including Alpha One (Gen 1 and Gen 2) and all Bravo series (I, II, and III).

This tool is a direct replacement for Mercury/MerCruiser part 91-78310 and other aftermarket equivalents.

• Material: Constructed from high-strength machined steel for durability.
• Installation: Designed for manual use with a standard socket wrench.
• Function: Used to remove and install hinge pins from the bell housing.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 x Hinge Pin Tool (Replaces 91-78310)

Installation Guide

1. Secure the sterndrive in a stable position, trimming it to provide clear access to the hinge pins.
2. Align the Hinge Pin Tool with the head of the hinge pin you intend to remove.
3. Attach a standard socket wrench to the 12-point head of the tool.
4. Apply firm, steady pressure counter-clockwise to loosen and unthread the hinge pin from the gimbal housing.
5. Once the old pin is removed, clean the threads and prepare the new hinge pin for installation.
6. Position the new hinge pin and use the tool to thread it into place, turning clockwise.
7. Tighten the hinge pin to the manufacturer's specified torque to ensure a secure fit.

Troubleshooting & FAQ

Q: How do I confirm this tool will fit my sterndrive?
A: This tool is compatible with all Mercury MerCruiser Alpha One (Gen 1 and 2), Bravo (I, II, III, X, XR, XZ), MC-1, and MR sterndrive units. It is specifically designed as a direct replacement for OEM part number 91-78310 and related aftermarket parts.

Q: What makes this tool different from a standard socket?
A: This is a purpose-built tool machined to fit the unique shape of the sterndrive hinge pins perfectly. Using a standard socket or incorrect tool can strip the pin head, making removal extremely difficult.

Q: Do I need any other special tools for the job?
A: While this tool addresses the hinge pin itself, you will need a standard socket wrench to operate it. We also recommend having a torque wrench to ensure the new pin is tightened to the correct OEM specification.

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.