{"product_id":"hinge-pin-tool-fits-mercury-mercruiser-alpha-one-gen-ii-bravo-sterndrives-replaces-91-78310-18-9861","title":"Hinge Pin Tool – Fits Mercury Mercruiser Alpha One, Gen II \u0026 Bravo Sterndrives (Replaces 91-78310, 18-9861)","description":"\u003csection\u003e\n\u003c!-- 🔧 Table Styles (include only once per page) --\u003e\n\u003cstyle\u003e\n  \/* Outer container allows horizontal scrolling (with iOS momentum) *\/\n  .ss-table-wrap { overflow-x:auto; -webkit-overflow-scrolling:touch; }\n\n  \/* Base table styles *\/\n  table.ss-table { width:100%; border-collapse:collapse; min-width:640px; }\n  table.ss-table th, table.ss-table td {\n    padding:10px 12px; border:1px solid #e5e7eb; text-align:left; vertical-align:top;\n  }\n\n  \/* Key: prevent wrapping, word breaks, and vertical text in headers *\/\n  table.ss-table th {\n    white-space:nowrap;       \/* Do not wrap *\/\n    word-break:normal;        \/* Don’t break words *\/\n    letter-spacing:normal;    \/* Prevent theme styles from stretching letters *\/\n    font-weight:600;\n    background:#f8fafc;\n  }\n\n  \/* Small screen optimization *\/\n  @media (max-width:480px){\n    table.ss-table th, table.ss-table td { padding:8px 10px; font-size:14px; }\n  }\n\u003c\/style\u003e\n\n\u003ch2\u003eProduct Details\u003c\/h2\u003e\n\u003cp\u003eThis \u003cstrong\u003eHinge Pin Tool\u003c\/strong\u003e is designed for the removal and installation of hinge pins on Mercury Mercruiser sterndrives, including Alpha One (Gen I \u0026amp; II), Bravo (I, II, \u0026amp; III), MC-1, R, and MR models from 1975 to the present. The tool is used on the hinge pin bolts to separate the sterndrive housing from the gimbal ring, simplifying service and maintenance.\u003c\/p\u003e\n\u003cp\u003eIt serves as a direct aftermarket replacement for Mercury part 91-78310, Sierra 18-9861, GLM 90200, and Mallory 9-79805.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eEngineered from hardened steel with a black oxide coating for durability.\u003c\/li\u003e\n  \u003cli\u003eFeatures a 12-point socket for a secure fit on the hinge pin bolt.\u003c\/li\u003e\n  \u003cli\u003eDesigned for manual use with a standard ratchet or breaker bar.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n\u003cp\u003eUse this matrix to confirm equivalent references across OEM and aftermarket.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Part Number Interchange\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eBrand\u003c\/th\u003e\n        \u003cth\u003ePart Number\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e91-78310\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSierra\u003c\/td\u003e\n        \u003ctd\u003e18-9861\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGLM\u003c\/td\u003e\n        \u003ctd\u003e90200\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMallory\u003c\/td\u003e\n        \u003ctd\u003e9-79805\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eEngine \u0026amp; Model Compatibility\u003c\/h2\u003e\n\u003cp\u003eConfirm your engine model\/year in the table below.\u003c\/p\u003e\n\u003cp\u003eFor Mercury Mercruiser Sterndrives, this tool applies to the gimbal ring hinge pins on the following units.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Compatible Engine Models\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eModel\u003c\/th\u003e\n        \u003cth\u003eApplication\u003c\/th\u003e\n        \u003cth\u003eYears\u003c\/th\u003e\n        \u003cth\u003eOEM Part No.\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAlpha One\u003c\/td\u003e\n        \u003ctd\u003eSterndrive Units\u003c\/td\u003e\n        \u003ctd\u003e1975–1990\u003c\/td\u003e\n        \u003ctd\u003e91-78310\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAlpha One Gen II\u003c\/td\u003e\n        \u003ctd\u003eSterndrive Units\u003c\/td\u003e\n        \u003ctd\u003e1991–Present\u003c\/td\u003e\n        \u003ctd\u003e91-78310\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eBravo I\u003c\/td\u003e\n        \u003ctd\u003eSterndrive Units\u003c\/td\u003e\n        \u003ctd\u003eAll\u003c\/td\u003e\n        \u003ctd\u003e91-78310\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eBravo II\u003c\/td\u003e\n        \u003ctd\u003eSterndrive Units\u003c\/td\u003e\n        \u003ctd\u003eAll\u003c\/td\u003e\n        \u003ctd\u003e91-78310\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eBravo III\u003c\/td\u003e\n        \u003ctd\u003eSterndrive Units\u003c\/td\u003e\n        \u003ctd\u003eAll\u003c\/td\u003e\n        \u003ctd\u003e91-78310\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMC-1\u003c\/td\u003e\n        \u003ctd\u003eSterndrive Units\u003c\/td\u003e\n        \u003ctd\u003eAll\u003c\/td\u003e\n        \u003ctd\u003e91-78310\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eR\u003c\/td\u003e\n        \u003ctd\u003eSterndrive Units\u003c\/td\u003e\n        \u003ctd\u003eAll\u003c\/td\u003e\n        \u003ctd\u003e91-78310\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMR\u003c\/td\u003e\n        \u003ctd\u003eSterndrive Units\u003c\/td\u003e\n        \u003ctd\u003eAll\u003c\/td\u003e\n        \u003ctd\u003e91-78310\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specs\u003c\/h2\u003e\n\u003cdl\u003e\n  \u003cdt\u003eProduct Type\u003c\/dt\u003e\n\u003cdd\u003eHinge Pin Removal\/Installation Tool\u003c\/dd\u003e\n  \u003cdt\u003eMaterial\u003c\/dt\u003e\n\u003cdd\u003eHardened Steel with Black Oxide Coating\u003c\/dd\u003e\n  \u003cdt\u003eConnection\u003c\/dt\u003e\n\u003cdd\u003e12-Point Socket End\u003c\/dd\u003e\n  \u003cdt\u003eFunction\u003c\/dt\u003e\n\u003cdd\u003eRemoval and installation of hinge pin from drives\u003c\/dd\u003e\n  \u003cdt\u003eApplication\u003c\/dt\u003e\n\u003cdd\u003eUsed on hinge pin bolts to separate housing from gimbal ring\u003c\/dd\u003e\n  \u003cdt\u003eInstallation\u003c\/dt\u003e\n\u003cdd\u003eHand Tool - Use with Ratchet or Breaker Bar\u003c\/dd\u003e\n  \u003cdt\u003eDimensions\u003c\/dt\u003e\n\u003cdd\u003eApprox. 52 × 16 × 16 mm (2.05 × 0.63 × 0.63 in)\u003c\/dd\u003e\n  \u003cdt\u003eWeight\u003c\/dt\u003e\n\u003cdd\u003e0.06 kg (2.11 oz)\u003c\/dd\u003e\n\u003c\/dl\u003e\n\n\u003ch2\u003eWhat’s in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e1 × Hinge Pin Tool (Replaces 91-78310 \/ 18-9861)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n  \u003cli\u003eEnsure the engine is off and the battery is disconnected for safety.\u003c\/li\u003e\n  \u003cli\u003eTrim the sterndrive to the full up position to access the hinge pins.\u003c\/li\u003e\n  \u003cli\u003ePlace the hinge pin tool onto the pin bolt head securely.\u003c\/li\u003e\n  \u003cli\u003eAttach a standard ratchet or breaker bar to the tool.\u003c\/li\u003e\n  \u003cli\u003eApply steady, even pressure to loosen and remove the hinge pin bolt.\u003c\/li\u003e\n  \u003cli\u003eClean the threads and surrounding area before installing the new pin.\u003c\/li\u003e\n  \u003cli\u003eUse the tool to carefully thread in and tighten the new hinge pin bolt.\u003c\/li\u003e\n  \u003cli\u003eTorque the bolt to the manufacturer's recommended specification.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\u003csummary\u003eWhich Mercruiser drives is this tool specifically for?\u003c\/summary\u003e\u003cp\u003eThis tool is designed for a wide range of Mercruiser sterndrives, including Alpha One (both Gen I and Gen II), all Bravo models (I, II, and III), MC-1, R, and MR drives from 1975 to the present.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eHow does this tool work?\u003c\/summary\u003e\u003cp\u003eThe tool fits over the hinge pin bolts that connect the sterndrive housing to the gimbal ring. By attaching a ratchet or breaker bar, you can apply the necessary torque to loosen or tighten these specific bolts for removal or installation.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat is the difference between this tool and the OEM part 91-78310?\u003c\/summary\u003e\u003cp\u003eThis is an aftermarket tool designed to meet or exceed the specifications of the original OEM tool. It performs the same function and is made from comparable hardened steel materials but is available at a more competitive price point.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat are the signs that my hinge pins need service?\u003c\/summary\u003e\u003cp\u003eCommon symptoms include excessive play or looseness in the sterndrive, difficulty steering, or unusual noises while turning or trimming the drive. A visual inspection may also reveal corrosion or wear on the pins.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eThe tool isn't fitting the hinge pin bolt correctly. What could be the issue?\u003c\/summary\u003e\u003cp\u003eFirst, confirm you are working on a compatible Mercruiser model. Check for corrosion or damage on the bolt head that may be preventing a secure fit. Ensure the tool's 12-point socket end is clean and free of debris.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs this tool necessary for replacing the gimbal bearing?\u003c\/summary\u003e\u003cp\u003eYes, removing the sterndrive housing from the gimbal ring is a required step for accessing and replacing the gimbal bearing. This tool is essential for that process.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat is the difference between OEM and aftermarket parts?\u003c\/summary\u003e\u003cp\u003eThis 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.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat are the shipping speed and cost?\u003c\/summary\u003e\u003cp\u003eWe ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat is your warranty and returns policy?\u003c\/summary\u003e\u003cp\u003eCovered 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 \u0026amp; in original condition). See our policy page or reach out for instructions.\u003c\/p\u003e\u003c\/details\u003e\n\n\u003ch2\u003eSafety \u0026amp; Important Info\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eVerify images\/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.\u003c\/li\u003e\n  \u003cli\u003eThis is an aftermarket replacement, not an OEM component.\u003c\/li\u003e\n  \u003cli\u003eProfessional installation is recommended for safety and performance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eAbout Sea Sierra\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cb\u003ePro-Grade Standards\u003c\/b\u003e — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cb\u003eFast Global Fulfillment\u003c\/b\u003e — Free standard delivery to most regions in 5–15 days.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cb\u003eManufacturer-Direct Value\u003c\/b\u003e — Fair pricing without compromising on materials or QC.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50717903028539,"sku":"MX-ZI9H-PGFB","price":9.45,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/MX-ZI9H-PGFB.png?v=1762937944","url":"https:\/\/seasierra.com\/products\/hinge-pin-tool-fits-mercury-mercruiser-alpha-one-gen-ii-bravo-sterndrives-replaces-91-78310-18-9861","provider":"SeaSierra","version":"1.0","type":"link"}