{"product_id":"sierra-18-1155-ball-bearing-for-mercury-outboard-gearcase-replaces-30-88957a1","title":"Sierra Ball Bearing 18-1155, Replaces Mercury Marine 30-88957A1, 30-88957T, for Counter Rotation Gearcase Applications","description":"\u003cp\u003eThis Sierra 18-1155 ball bearing is a gearcase bearing built for counter rotation outboard applications. It is manufactured from alloy steel for durability under the load and rotational demands of a lower unit gearcase, and it is finished in white. The bearing measures 0.39 x 0.39 x 0.39 inches and weighs 0.89 pounds, making it a compact precision component sized for direct fitment into the gearcase housing it was designed for.\u003c\/p\u003e\u003cp\u003eAs a Sierra-branded part, it is built to serve as a direct equivalent for the OEM Mercury Marine numbers it replaces, giving outboard owners and marine technicians a reliable option when rebuilding or servicing a counter rotation lower unit. Ball bearings like this one support the pinion and gear assembly inside the gearcase, keeping rotating components properly aligned and reducing friction and wear during operation. Because it is designated specifically for counter rotation applications, it is important to confirm that your outboard's gearcase is a counter rotation unit before ordering, since standard rotation gearcases use a different bearing.\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 18-1155\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBearing Type:\u003c\/strong\u003e Ball Bearing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Counter Rotation Gearcase Applications\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Alloy Steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\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 0.89 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999309303\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 30-88957A1, 30-88957T\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eFor counter rotation gearcase applications\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercury Marine 30-88957A1\u003c\/li\u003e\n\u003cli\u003eMercury Marine 30-88957T\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Sierra 18-1155 bearing used for?\u003c\/strong\u003e The Sierra 18-1155 is a ball bearing used inside an outboard gearcase to support the pinion and gear assembly in counter rotation applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-1155 fit a standard rotation gearcase?\u003c\/strong\u003e No. The 18-1155 is designated for counter rotation applications, so it should not be used in a standard rotation gearcase; confirm your gearcase rotation before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM numbers does the 18-1155 replace?\u003c\/strong\u003e It replaces Mercury Marine 30-88957A1 and 30-88957T, so either OEM number can be cross-referenced to Sierra part 18-1155.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the 18-1155 ball bearing made from?\u003c\/strong\u003e It is made from alloy steel, giving it the strength needed to handle continuous rotation and load inside the gearcase.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat size is the Sierra 18-1155 bearing?\u003c\/strong\u003e The 18-1155 measures 0.39 x 0.39 x 0.39 inches, a compact size built to fit precisely into its designated gearcase bore.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-1155 bearing weigh?\u003c\/strong\u003e The Sierra 18-1155 ball bearing weighs 0.89 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-1155 a genuine Sierra part or a knockoff?\u003c\/strong\u003e It is a genuine Sierra International branded ball bearing, part number 18-1155, not a generic substitute.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the 18-1155 bearing?\u003c\/strong\u003e The 18-1155 has a white finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order the 18-1155?\u003c\/strong\u003e Each order of the Sierra 18-1155 includes one ball bearing unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the 18-1155 be identified by its UPC?\u003c\/strong\u003e Yes, the Sierra 18-1155 ball bearing carries UPC 030999309303 for identification and ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat lubricant is compatible with the 18-1155 bearing?\u003c\/strong\u003e The 18-1155 ball bearing is designed for use with grease as its compatible lubricant.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988086894811,"sku":"SIE-18-1155","price":44.52,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-1155_lg__88277.1558121730.500.750.jpg?v=1785188717","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-1155-ball-bearing-for-mercury-outboard-gearcase-replaces-30-88957a1","provider":"Good Vibes Marina","version":"1.0","type":"link"}