{"product_id":"3-8mm-brass-rc-car-wheels-shaft-motor-flexible-coupling-coupler-hex-connector","title":"3-8mm Brass RC Car Wheels Shaft Motor Flexible Coupling Coupler Hex Connector","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003e3–8mm Flexible Shaft Coupling Coupler — Precision Hex Connector for RC Cars \u0026amp; Motors\u003c\/h2\u003e\n\u003cp\u003eWhen a misaligned motor shaft causes vibration, slippage, or premature wear on your RC car or DIY drive system, the root cause is almost always a poorly fitted coupler. Hobbyists, robotics builders, and RC enthusiasts who demand tight tolerances and reliable torque transfer need a flexible shaft coupling that holds its position under load without stripping or loosening.\u003c\/p\u003e\n\u003cp\u003eThese flexible coupling couplers are available in two materials — brass and 45 steel — and span a shaft diameter range of 2mm to 8mm (approximately 0.079 in to 0.315 in). Each hex connector is machined to close tolerances, with a set-screw locking mechanism that grips the shaft securely. Packing options include 1, 2, 4, or 10 pieces per order to suit single builds or bulk workshop stock.\u003c\/p\u003e\n\u003cp\u003eTypical use cases include RC car wheel-to-motor shaft connections, small DC motor couplings in desktop CNC and 3D printer extruder drives, and flexible shaft joints in DIY robotics arm assemblies — all scenarios where a rigid coupling would crack under slight angular misalignment.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-compat\"\u003e\n\u003cspan class=\"hdiy-compat-icon\"\u003e🔧\u003c\/span\u003e\n\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Fits standard round motor shafts from 2mm to 8mm (0.079\"–0.315\"). Compatible with most RC car motors, hobby DC motors, stepper motors, and small servo shafts. Verify your shaft diameter before ordering.\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003ch2\u003e✅ Key Features of These Flexible Shaft Coupling Couplers\u003c\/h2\u003e\n\u003cul class=\"hdiy-list\"\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e⚙️\u003c\/span\u003e\u003cstrong\u003eWide Size Range:\u003c\/strong\u003e Available in 2, 3, 3.17, 4, 5, 6, 7, and 8mm shaft diameters to cover the most common RC and hobby motor shaft standards.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\u003cstrong\u003eDual Material Options:\u003c\/strong\u003e Choose brass for corrosion resistance and lightweight performance, or 45 steel for higher torque loads and greater mechanical strength.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🎯\u003c\/span\u003e\u003cstrong\u003eHex Connector Design:\u003c\/strong\u003e The hex-profile bore and set-screw locking system prevents rotational slippage, maintaining consistent shaft engagement under dynamic loads.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\u003cstrong\u003eFlexible Coupling Action:\u003c\/strong\u003e Absorbs minor angular and parallel misalignment between motor and driven shaft, reducing vibration transmission and protecting bearings.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📦\u003c\/span\u003e\u003cstrong\u003eFlexible Pack Quantities:\u003c\/strong\u003e Order 1, 2, 4, or 10 pieces — ideal for single project builds, spares kits, or workshop bulk stock.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🏗️\u003c\/span\u003e\u003cstrong\u003eBroad Application Fit:\u003c\/strong\u003e Suited for RC cars, desktop CNC machines, 3D printer extruder drives, DIY robotics, and small automation systems requiring reliable shaft-to-shaft connection.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ch2\u003e📐 Technical Specifications — Flexible Shaft Coupling Coupler\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eShaft Diameter Range\u003c\/th\u003e\n\u003ctd\u003e2mm – 8mm (0.079\" – 0.315\")\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eAvailable Sizes\u003c\/th\u003e\n\u003ctd\u003e2mm, 3mm, 3.17mm, 4mm, 5mm, 6mm, 7mm, 8mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial Options\u003c\/th\u003e\n\u003ctd\u003eBrass \/ 45 Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eConnector Type\u003c\/th\u003e\n\u003ctd\u003eHex Flexible Coupling with Set Screw\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBore Tolerance\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOverall Length\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFinish\u003c\/th\u003e\n\u003ctd\u003eNatural machined (Brass) \/ Oxide-treated (45 Steel)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePacking Quantity\u003c\/th\u003e\n\u003ctd\u003e1 pcs \/ 2 pcs \/ 4 pcs \/ 10 pcs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eApplication\u003c\/th\u003e\n\u003ctd\u003eRC cars, hobby motors, CNC, robotics, 3D printers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-faq\"\u003e\n\u003ch2\u003e❓ Frequently Asked Questions\u003c\/h2\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow do I choose the right shaft diameter for my motor?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eMeasure your motor output shaft with a digital caliper. Match that measurement to the available sizes: 2mm, 3mm, 3.17mm, 4mm, 5mm, 6mm, 7mm, or 8mm. If your shaft falls between sizes, always size down and use the set screw to secure — never force a coupler that is too small onto a shaft.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the difference between the brass and 45 steel versions?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBrass couplers are lighter, naturally corrosion-resistant, and well-suited for low-to-medium torque applications such as RC car wheel hubs and small hobby motors. The 45 steel variants offer higher tensile strength and are better suited for applications with greater torque demands, such as CNC spindle couplings or heavier drive systems. For most RC car builds, brass is the practical choice.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWill this coupler resist rust or corrosion outdoors?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBrass couplers offer inherent corrosion resistance and perform well in humid or mildly wet outdoor environments. The 45 steel versions have an oxide surface treatment that provides basic protection, but for prolonged outdoor or wet exposure, brass is the recommended choice. Applying a light machine oil to steel couplers after use will extend their service life.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eAre these couplers compatible with stepper motors and servo shafts?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. These flexible shaft couplings are compatible with most standard round motor shafts including DC hobby motors, stepper motors, and small servo output shafts, provided the shaft diameter matches one of the available sizes (2–8mm). Always confirm your shaft is round and within the listed diameter range before ordering.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow strong is the set-screw grip — will it slip under load?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe hex bore combined with the set screw provides a secure mechanical lock on the shaft. For typical RC car and hobby motor torque levels, slippage is not expected under normal operating conditions. For very high-torque applications, consider applying a small amount of thread-locking compound to the set screw for added security.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I use one coupler to connect two different shaft diameters?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eNo — each coupler listed here is a single-bore size designed for shafts of the same diameter on both ends. If you need to connect two shafts of different diameters, you would require a reducing or stepped coupling, which is a different product type. Check the variant options carefully and match both shaft ends before purchasing.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow many pieces should I order for a typical RC car build?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eMost RC car builds require 2 to 4 couplers depending on the drivetrain configuration (2WD vs 4WD). The 2-piece and 4-piece packing options are the most popular for single vehicle builds. The 10-piece pack offers the best per-unit value for workshop stock or multi-vehicle projects.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-cta\"\u003e\n🛒 Select your size, material, and packing quantity above, then add to cart.\n\u003c\/div\u003e\n\n\u003c\/div\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How do I choose the right shaft diameter for my motor?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Measure your motor output shaft with a digital caliper. Match that measurement to the available sizes: 2mm, 3mm, 3.17mm, 4mm, 5mm, 6mm, 7mm, or 8mm. If your shaft falls between sizes, always size down and use the set screw to secure.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the difference between the brass and 45 steel versions?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Brass couplers are lighter, naturally corrosion-resistant, and suited for low-to-medium torque applications. The 45 steel variants offer higher tensile strength for greater torque demands such as CNC spindle couplings.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Will this coupler resist rust or corrosion outdoors?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Brass couplers offer inherent corrosion resistance for humid or mildly wet environments. The 45 steel versions have an oxide surface treatment for basic protection. Applying light machine oil to steel couplers after use extends service life.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Are these couplers compatible with stepper motors and servo shafts?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes, compatible with most standard round motor shafts including DC hobby motors, stepper motors, and small servo output shafts, provided the shaft diameter matches one of the available sizes (2–8mm).\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How strong is the set-screw grip — will it slip under load?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The hex bore combined with the set screw provides a secure mechanical lock. For typical RC car and hobby motor torque levels, slippage is not expected. For very high-torque applications, apply thread-locking compound to the set screw.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can I use one coupler to connect two different shaft diameters?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"No — each coupler is a single-bore size designed for shafts of the same diameter on both ends. To connect two shafts of different diameters, a reducing or stepped coupling is required.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How many pieces should I order for a typical RC car build?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Most RC car builds require 2 to 4 couplers depending on drivetrain configuration. The 2-piece and 4-piece packing options suit single vehicle builds. The 10-piece pack offers the best per-unit value for workshop stock.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"8mm \/ Brass \/ 1 pcs","offer_id":52421723652370,"sku":"GYZLPJSCS00092x1","price":2.46,"currency_code":"USD","in_stock":true},{"title":"3mm \/ Brass \/ 1 pcs","offer_id":52421723685138,"sku":"GYZLPJSCS00093x1","price":2.46,"currency_code":"USD","in_stock":true},{"title":"2mm \/ Brass \/ 1 pcs","offer_id":52421723717906,"sku":"GYZLPJSCS00094x1","price":2.46,"currency_code":"USD","in_stock":true},{"title":"3.17mm \/ Brass \/ 1 pcs","offer_id":52421723750674,"sku":"GYZLPJSCS00095x1","price":2.46,"currency_code":"USD","in_stock":true},{"title":"5mm \/ 45 steel \/ 1 pcs","offer_id":52421723783442,"sku":"GYZLPJSCS00096x1","price":2.46,"currency_code":"USD","in_stock":true},{"title":"6mm \/ 45 steel \/ 1 pcs","offer_id":52421723816210,"sku":"GYZLPJSCS00097x1","price":2.46,"currency_code":"USD","in_stock":true},{"title":"5mm \/ Brass \/ 1 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