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When a loose or mismatched shaft coupling causes vibration, wobble, or power loss in your RC build, the entire drivetrain suffers. Hobbyists, makers, and RC enthusiasts who demand a clean, rattle-free connection between motor and drive shaft need a coupler that grips firmly and transfers torque without slip. These flexible shaft brass motor connector couplers deliver exactly that — a solid, rigid link engineered for the tight tolerances of RC cars, RC boats, and small motorized assemblies.
Each coupler is machined from brass, offering a balance of machinability, corrosion resistance, and moderate weight suited to small-scale drivetrains. The rigid coupling body accepts two shaft diameters — an input side and an output side — spanning from 2mm to 6mm (approximately 0.079 in to 0.236 in). Set screws on each end lock the coupler firmly onto both shafts. Available in 24 model combinations and in quantities of 1, 5, or 10 pieces per order.
Typical use cases include connecting a brushed or brushless motor shaft to a propeller shaft in RC boat builds, linking a motor output to a gearbox input shaft in RC car drivetrains, and serving as a shaft adapter in DIY robotics or small CNC axis assemblies where two different shaft diameters must be joined inline.
Machined brass body provides firm torque transfer with no flex or slip between motor and drive shaft — ideal for RC drivetrains where alignment matters.
Input and output bore sizes range from 2mm to 6mm, covering the most common motor shaft and drive shaft diameters used in RC cars, RC boats, and small robotics.
Each end features a set screw that clamps directly onto the shaft, preventing rotation slip and axial movement under load during operation.
Small-diameter brass body keeps added mass minimal — important for RC builds where weight distribution and balance affect handling and speed.
Brass naturally resists oxidation in humid or splash-prone environments, making these couplers a reliable choice for RC boat applications exposed to water.
Order 1, 5, or 10 pieces per model — stock up for a fleet build, a repair kit, or a single replacement without overpaying for unnecessary extras.
| Material | Brass |
|---|---|
| Input Bore Diameter Range | 2mm – 6mm (0.079" – 0.236") |
| Output Bore Diameter Range | 2mm – 6mm (0.079" – 0.236") |
| Available Model Combinations | 24 (see variant options) |
| Locking Method | Set screw (both ends) |
| Coupling Type | Rigid shaft coupler |
| Outer Diameter | See variant options |
| Overall Length | See variant options |
| Finish | Natural brass |
| Compatible Applications | RC car, RC boat, DIY robotics, small CNC |
| Available Quantities | 1 Pcs / 5 Pcs / 10 Pcs |
Measure the outer diameter (OD) of your motor shaft and the OD of your drive shaft using a caliper. Then select the model that matches those two diameters — for example, "3mm to 4mm" means the input bore is 3mm and the output bore is 4mm. If both shafts are the same diameter, choose a same-size model such as "3mm to 3mm".
This is a rigid coupling. It creates a solid, non-flexible connection between two shafts. This is ideal when your motor and drive shaft are well-aligned. If your application has angular or parallel misalignment, a flexible jaw coupler or spider coupler would be more appropriate.
Yes. Brass has inherent corrosion resistance and performs well in splash or humid environments typical of RC boat use. It will not rust like steel. For prolonged submersion, applying a light coat of waterproof grease around the set screw area is recommended as a precaution.
The set screws are typically hex socket (Allen key) type. A metric hex key set is recommended. The exact hex key size depends on the set screw diameter, which varies by coupler model — typically 1.5mm to 2.5mm hex keys cover the range used in these small couplers. Contact us to confirm the exact size for your selected model.
Yes, provided the motor output shaft diameter and the gearbox input shaft diameter match the bore sizes of your selected model. This is a common use case in RC car drivetrains and small motorized assemblies. Ensure both shafts have a flat or D-cut if you need maximum torque grip; round shafts rely solely on set screw clamping force.
Multi-piece packs offer a lower per-unit cost and are practical if you are building multiple RC vehicles, maintaining a repair kit, or running a workshop. Couplers are wear items in high-use drivetrains, so having spares on hand avoids downtime when one needs replacement.
Yes. Several models include a 3.175mm bore, which corresponds to the 1/8" shaft diameter widely used in North American RC cars and boats. Look for models labeled "3.175mm" on either the input or output side to match your specific shaft combination.
