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

Bearing upgrade for small rotating shafts

This replacement ball bearing pack is designed for compact rotating shafts and tight drivetrain positions in Hirobo helicopter assemblies and other small RC components. The pack includes 2 bearings, each 3 x 9 x 4 mm, for applications where space is limited but reliable axial and radial support is needed.

Used as support points for motor pinions, miniature gear stages, and auxiliary shafts, these bearings reduce play and promote smooth rotation to help responsiveness. The listing notes the reference 93ZZ, identifying a shielded bearing type that offers moderate protection against particles without adding bulk.

Installation tips: inspect mating parts for wear, ensure inner and outer diameters match the 3 x 9 x 4 mm profile, press bearings in using a tool that bears on the outer race to protect the internal elements, and add light lubrication only if part of your maintenance schedule.

Tuning notes: change bearings in matched pairs to keep wear balanced, check for axial play after installation, and treat bearing condition as a first check when chasing vibration or noise issues in rotors and small gear trains.