For small RC drivetrains: Hirobo HI2500016 Flanged Ball Bearing 4 x 9 x 4 mm, 2 pcs  [HI2500016]

Bearing fit and setup advice

This Hirobo flanged ball bearing is a 4 x 9 x 4 mm component supplied as two pieces. The flange provides a bearing face that controls axial movement when housings or collars cannot accept deeper seating.

Functioning as a rolling-element bearing, it reduces friction and maintains rotational alignment in small drivetrains and linkages under typical light to moderate loads. Use the 4 x 9 x 4 mm sizing as the compatibility reference for shafts and housings.

During installation, aim for a clean press fit or use an appropriate retention method, avoid eccentric loading on the flange, and check the bearing for smooth rotation before locking assemblies together. In tuning, fresh, correctly sized bearings help recover responsiveness and reduce wasted energy in the drivetrain.

Packing: Sold as 2 pcs per pack.