{"product_id":"castair-replacement-motor-sd-hub-1-5-8-shaft-sd158","title":"Castair Replacement Motor SD Hub 1 5\/8\" Shaft SD158","description":"\u003ch2\u003eCastair SD158 — Replacement Motor SD Hub, 1-5\/8\" Shaft\u003c\/h2\u003e\n\n\u003cp\u003eThe Castair SD158 is a replacement SD-series motor hub for 1-5\/8-inch motor output shafts used in Cast Air belt-driven compressor installations. This is the larger SD hub — the 1-5\/8-inch shaft diameter is typically found on motors in the 5 HP and above range where the motor's output shaft steps up from the 1-3\/8-inch size used on smaller compressors. When the motor hub fails on these larger-shaft applications, the SD158 is the correct replacement.\u003c\/p\u003e\n\n\u003cp\u003eThe SD designation identifies the hub series — SD hubs are used on specific Cast Air compressor models and are not interchangeable with SK-series hubs. If you are not certain whether your compressor uses an SD or SK hub, look at the existing hub for a part number stamp, or call us with your compressor model number and we will confirm the correct part before you order.\u003c\/p\u003e\n\n\u003ch3\u003eWhat the Motor Hub Does\u003c\/h3\u003e\n\u003cp\u003eThe motor hub mounts to the electric motor's output shaft and carries the drive sheave that transfers power to the compressor pump via V-belt. On startup, the hub takes the full torque spike of the motor coming up to speed under load. Over extended service, the bore can wear out of round, keyways can enlarge, or the hub body can fatigue and crack. Any of these conditions lead to vibration, belt slippage, and alignment problems that cannot be corrected by belt tension alone. The solution is a direct hub replacement with the correct OEM part.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eShaft Size: 1-5\/8 inch:\u003c\/strong\u003e Machines to fit motor output shafts measuring 1.625 inches in diameter — measure your shaft with a caliper before ordering\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSD Series Hub:\u003c\/strong\u003e Matched to Cast Air SD-series hub applications — verify your compressor uses SD-series hubs before ordering (see note below on SD vs. SK)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOEM Cast Air Part:\u003c\/strong\u003e Manufactured to Cast Air specifications for correct bore tolerance and fit\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrecision Machined Bore:\u003c\/strong\u003e Correct tolerance prevents shaft slop that causes pulley runout and misalignment\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBelt-Drive Application:\u003c\/strong\u003e Designed for belt-driven Cast Air compressor configurations where motor-to-pump power transfer is via sheave and V-belt\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e SD158\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eShaft Diameter:\u003c\/strong\u003e 1-5\/8 inch (1.625\")\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHub Series:\u003c\/strong\u003e SD\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eComponent Type:\u003c\/strong\u003e Replacement motor drive hub\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Cast Air (Castair)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $31.57\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSD and SK Hub Series — Know Which You Need\u003c\/h3\u003e\n\u003cp\u003eCast Air uses two hub series — SD and SK — on different compressor configurations. They are not interchangeable. Check your existing hub for a part number, or call us with your compressor model to confirm.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSD138\u003c\/strong\u003e — SD series, 1-3\/8\" shaft ($31.57)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSD158\u003c\/strong\u003e — SD series, 1-5\/8\" shaft ($31.57). This product.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSK158\u003c\/strong\u003e — SK series, 1-5\/8\" shaft ($52.36)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSK178\u003c\/strong\u003e — SK series, 1-7\/8\" shaft ($52.36)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhen Does a Shop Need the SD158\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eReplace the motor hub when:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eThe existing hub on a larger-shaft Cast Air compressor shows cracking, bore wear, or visible keyway damage\u003c\/li\u003e\n  \u003cli\u003eThe compressor vibrates unusually at startup or during operation — often caused by a hub that has gone loose on the shaft\u003c\/li\u003e\n  \u003cli\u003eBelt alignment problems persist despite correct tension and sheave alignment — indicating hub bore runout\u003c\/li\u003e\n  \u003cli\u003eInstalling a replacement motor with a 1-5\/8-inch output shaft on an SD-series compressor configuration\u003c\/li\u003e\n  \u003cli\u003ePreventive maintenance — stocking the correct hub before the original fails\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003cstrong\u003eAuthorized Cast Air dealer since 2016\u003c\/strong\u003e\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFree shipping\u003c\/strong\u003e on qualifying orders\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFree technical support\u003c\/strong\u003e at 866-217-0063 — confirm SD vs. SK series and correct shaft size before ordering\u003c\/li\u003e\n  \u003cli\u003e\u003cstrong\u003eFull manufacturer warranty\u003c\/strong\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eCall 866-217-0063 for quick answers and help!\u003c\/strong\u003e\u003c\/p\u003e","brand":"Cast Air","offers":[{"title":"Default Title","offer_id":53342601871573,"sku":"SD158","price":58.22,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/CastairReplacementAirCompressorMotorHub_4fa232c6-21d5-4e39-b9e6-a99cc9a16eab.png?v=1772652928","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-replacement-motor-sd-hub-1-5-8-shaft-sd158","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}