Hirobo HI2500114 Ball Bearing 3 x 9 x 4 mm 2 pcs  [HI2500114]

Ball bearing for RC helicopter parts

This replacement ball bearing set is an RC-scale accessory intended for small rotating shafts and compact drivetrain locations in Hirobo helicopter assemblies and other general RC parts. The pack contains 2 pcs of bearings sized 3 x 9 x 4 mm, suitable when compact axial and radial support is required in tight spaces.

In practical use the bearings serve as support points for motor pinions, small gear stages, and secondary shafts where limiting play and ensuring smooth rotation improves overall responsiveness. The product identifier includes the reference 93ZZ which indicates a shielded bearing style noted in the original name, useful where moderate debris protection is needed.

Installation notes: inspect mating shafts and housings for wear, confirm inner and outer diameters match the 3 x 9 x 4 mm profile, press bearings squarely using a tool that contacts the outer race to avoid damaging the rolling elements, and apply light lubrication suited for small RC bearings if required by your maintenance routine.

Maintenance and tuning: replace bearings in pairs for symmetric wear, check for endplay after fitting, and consider bearing condition when diagnosing vibration or noise issues in rotors and small gear trains.