Hirobo HI2500114 3 x 9 x 4 mm Replacement Bearings (2 pcs)  [HI2500114]

Compatibility notes for small RC gear trains

This replacement ball bearing set suits small rotating shafts and constrained drivetrain spaces in Hirobo helicopter assemblies and other RC parts. The kit contains two bearings sized 3 x 9 x 4 mm intended for locations where compact axial and radial support is required.

They are commonly fitted as supports for motor pinions, miniature gear stages, and secondary shafts to limit play and keep rotation smooth, which helps overall control response. The product reference 93ZZ signifies a shielded bearing variant mentioned in the original name, providing modest contamination resistance for many hobby uses.

Fitting guidance: check shafts and housing bores for damage, confirm the 3 x 9 x 4 mm dimensions match before assembly, push the bearings in squarely using a tool that contacts the outer race to avoid harming internal components, and use light lubrication if specified by your routine service practice.

Troubleshooting: replace bearings as matched pairs to avoid uneven wear, verify there is no unintended endplay after installation, and include bearing state when assessing vibration or abnormal noise coming from rotors or compact gear trains.