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Hinge Pin Tool – Fits Mercury Mercruiser Alpha One, Gen II & Bravo Sterndrives (Replaces 91-78310, 18-9861)
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Hinge Pin Tool – Fits Mercury Mercruiser Alpha One, Gen II & Bravo Sterndrives (Replaces 91-78310, 18-9861)
This hinge pin removal and installation tool is designed for use with Mercury Mercruiser sterndrives including Alpha One, Alpha One Gen II, Bravo I, II & III, MC-1, R, and MR models from 1975 to the present. It facilitates the removal and installation of hinge pins from drive units, specifically targeting hinge pin bolts that separate the housing from the gimbal ring.
Direct replacements for this tool include Mercury part number 91-78310, Sierra 18-9861, GLM 90200, and Mallory 9-79805, making it a versatile choice for maintenance and repair tasks.
- Includes 1x hinge pin tool (91-78310/18-9861)
- Hand tool designed for use with a ratchet or breaker bar
- Compatible with multiple Mercury Mercruiser sterndrive models spanning decades
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Mercury | 91-78310 |
| Sierra | 18-9861 |
| GLM | 90200 |
| Mallory | 9-79805 |
Compatible Engine Models
Confirm your engine model/year in the table below. For Mercury owners, here9s a guide to help you identify your engine9s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.
| Model | Application | Years | OEM Part No. |
|---|---|---|---|
| Alpha One | Sterndrive Units | 1975 61990 | 91-78310 |
| Alpha One Gen II | Sterndrive Units | 1991 61990Present | 91-78310 |
| Bravo I | Sterndrive Units | All | 91-78310 |
| Bravo II | Sterndrive Units | All | 91-78310 |
| Bravo III | Sterndrive Units | All | 91-78310 |
| MC-1 | Sterndrive Units | All | 91-78310 |
| R | Sterndrive Units | All | 91-78310 |
| MR | Sterndrive Units | All | 91-78310 |
Technical Specifications
| Specification | Value |
|---|---|
| Product Type | Hinge Pin Removal/Installation Tool |
| Installation | Hand Tool - Use with Ratchet or Breaker Bar |
| Material | Hardened Steel with Black Oxide Coating |
| Connection | 12-Point Socket End |
| Dimensions | Approx. 52 7 16 7 16 mm (2.05 7 0.63 7 0.63 in) |
| Weight | 0.06 kg (2.11 oz) |
| Function | Removal and installation of hinge pin from drives |
| Application | Specifically used on hinge pin bolts to separate housing from gimbal ring |
| Compatible Hardware | Alpha One, Gen II, Bravo I, II & III gimbal ring hinge pins |
Package Contents
- 1 D7 Hinge Pin Tool (91-78310/18-9861)
Installation Guide
- Confirm the engine model and year to ensure compatibility.
- Prepare a ratchet or breaker bar to use with the tool.
- Fit the 12-point socket end of the hinge pin tool onto the hinge pin bolt.
- Use the ratchet or breaker bar to carefully loosen and remove the hinge pin bolt.
- To install, align the hinge pin tool with the hinge pin bolt in the gimbal ring.
- Use the ratchet or breaker bar to tighten the hinge pin securely.
- Check that the housing and gimbal ring are properly separated or connected as needed.
- Inspect the tool for any wear or damage after use to maintain performance.
- Store the tool in a dry, safe place to prevent corrosion.
Troubleshooting & FAQ
- How do I confirm this fits my engine?
- Verify your engine model and year against the compatibility table provided. Use the guides linked to identify your engine serial/model for accurate fitment.
- What are the differences versus an OEM tool?
- This is an aftermarket replacement part built to OEM specifications using comparable-grade materials. Production occurs in an ISO9002-certified facility with consistent batch inspections.
- How often should I replace the hinge pin tool?
- Replace the tool if it shows signs of wear, damage, or breakage to ensure safe and effective operation. Proper maintenance will extend its life.
- What are common failure signs during use?
- Difficulty in removing or installing hinge pins, tool slipping, or visible cracks indicate the tool should be replaced.
- OEM vs. Aftermarket?
- 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.
- How fast do you ship and how much does it cost?
- We offer fast global shipping 6typically 5 615 days worldwide 6and standard shipping is free. Expedited options are available at checkout depending on your location.
- What is your warranty and return policy?
- 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.
We can ship to virtually any address in the world with free shipping available for most regions.
For our typical US and Canadian customers , our shipping timeframes are as follows:
- Amazon FBA: orders will be delivered within 1-5 business days after placing the order (during certain special periods such as major promotions, Christmas, etc., the delivery time of Amazon FBA may be affected).
- US warehouse shipment: orders will be delivered within 5 days after placing the order.
- China warehouse shipment: orders will be delivered about 12 days after placing the order.
When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.
Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.
Founded in 2002, JLM Marine has established itself as a dedicated manufacturer of high-quality marine parts, based in China. Our commitment to excellence in manufacturing has earned us the trust of top marine brands globally.
As a direct supplier, we bypass intermediaries, which allows us to offer competitive prices without compromising on quality. This approach not only supports cost-efficiency but also ensures that our customers receive the best value directly from the source.
We are excited to expand our reach through retail channels, bringing our expertise and commitment to quality directly to boat owners and enthusiasts worldwide.
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