{"product_id":"sierra-18-1143-tapered-roller-bearing-replaces-mercury-mercruiser-31-36387a1-outboard-gearcase-bearing","title":"Sierra 18-1143 Tapered Roller Bearing, Replaces 31-42647A1, for Mercury Outboard Gearcase","description":"\u003cp\u003eThe Sierra 18-1143 Tapered Roller Bearing is a precision alloy steel bearing built for the gearcase of Mercury outboard motors. It is machined to original-equipment tolerances so it seats correctly on the pinion and drive shaft assemblies it is designed to support, carrying both radial and axial loads inside the lower unit. Alloy steel construction gives the bearing the hardness and load capacity needed to handle the constant thrust and rotational stress generated inside a marine gearcase, where heat, vibration, and water-adjacent operating conditions place extra demand on components.\u003c\/p\u003e\u003cp\u003eThis bearing is a direct cross-reference for the OEM number listed below, so it installs as a like-for-like replacement without modification. It ships as a single bearing, ready to be pressed into place using standard bearing installation tools and packed with the gearcase lubricant already used in the unit. Because tapered roller bearings wear gradually with use, replacing a worn 18-1143 during a gearcase rebuild or seal service helps restore proper shaft alignment and reduce play in the lower unit.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-1143\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Mercury Outboard Gearcase Bearing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Alloy Steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBearing Type:\u003c\/strong\u003e Tapered Roller Bearing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatible Lubricant:\u003c\/strong\u003e Grease\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eItem Dimensions:\u003c\/strong\u003e 0.39 x 0.39 x 0.39 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.55 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999752277\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCountry of Origin:\u003c\/strong\u003e United States\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMercury outboard gearcase assemblies using the 18-1143 tapered roller bearing position\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e31-42647A1\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-1143 tapered roller bearing fit?\u003c\/strong\u003e The 18-1143 is designed for the gearcase of Mercury outboard motors, where it supports the pinion and drive shaft assembly against radial and axial loads.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-1143 a direct OEM replacement?\u003c\/strong\u003e Yes, Sierra 18-1143 is a direct cross-reference for OEM number 31-42647A1 and installs in place of that original bearing without modification.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat size is the Sierra 18-1143 bearing?\u003c\/strong\u003e The 18-1143 tapered roller bearing measures 0.39 x 0.39 x 0.39 inches and weighs 0.55 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the 18-1143 bearing made from?\u003c\/strong\u003e It is made from alloy steel, giving the 18-1143 the hardness needed to handle the thrust and rotational loads inside a marine gearcase.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat lubricant should be used with the 18-1143 bearing?\u003c\/strong\u003e The Sierra 18-1143 is compatible with standard gearcase grease lubricant used during installation and ongoing service.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this a genuine Sierra part or an aftermarket copy?\u003c\/strong\u003e The 18-1143 is a genuine Sierra International part, manufactured to meet or exceed the specifications of the original equipment bearing it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat comes in the box with the 18-1143?\u003c\/strong\u003e Each order includes one Sierra 18-1143 tapered roller bearing; no additional hardware or seals are included.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow is the 18-1143 bearing installed?\u003c\/strong\u003e The 18-1143 is pressed into the gearcase housing using standard bearing installation tools, typically during a gearcase rebuild or seal replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy does a tapered roller bearing like the 18-1143 need replacing?\u003c\/strong\u003e Tapered roller bearings wear gradually with use, and a worn 18-1143 can allow shaft play or misalignment inside the lower unit, making replacement necessary during a rebuild.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-1143 come with a warranty?\u003c\/strong\u003e The Sierra 18-1143 tapered roller bearing carries Sierra's limited warranty covering manufacturing defects.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988086862043,"sku":"SIE-18-1143","price":42.12,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/8M0146566__99585.1737872775.500.750.jpg?v=1785188597","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-1143-tapered-roller-bearing-replaces-mercury-mercruiser-31-36387a1-outboard-gearcase-bearing","provider":"Good Vibes Marina","version":"1.0","type":"link"}