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

Compact ball bearings for small RC shafts

This replacement ball bearing set is an accessory for small rotating shafts and tight 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 and is intended where compact axial and radial support is required in confined spaces.

In service these bearings act as support points for motor pinions, small gear stages, and secondary shafts where reducing play and keeping rotation smooth helps responsiveness. The product identifier includes the reference 93ZZ, which denotes a shielded bearing style noted in the original name and offers moderate protection against debris.

Installation notes: inspect mating shafts and housings for wear, confirm the inner and outer diameters match the 3 x 9 x 4 mm specification, press the bearings squarely using a driver that contacts the outer race to avoid damaging the rolling elements, and use light lubrication suitable for small RC bearings if your maintenance routine calls for it.

Maintenance and tuning: fit bearings in pairs to even out wear, check for endplay after installation, and consider bearing condition when diagnosing vibration or noise in rotors and small gear trains.