Eagle/Freya/EX/SX bevel pinion gear set for Hirobo HI0404509 SX  [HI0404509]

Bevel pinion set details

This Hirobo HI0404509 SX bevel pinion gear set is an RC-scale replacement part intended for common parts used on Eagle, Freya, EX and SX helicopter platforms. It functions as the driven/driving interface on the motor-to-gearbox axis and is supplied as a matched set to maintain correct gear mesh in the tail or main transmission where bevel pinions are fitted.

Compatibility is indicated by product path and model references; the set is designed to match common mounting patterns and shaft diameters used across Eagle/Freya/EX/SX components. Do not assume fitment on unrelated frames without confirming shaft diameter and spline count from vendor listings or original parts diagrams.

Installation notes and tuning role: install the pinion set so gear faces run parallel and backlash is minimal but not zero, check for smooth rotation by hand before powering up, and confirm alignment with any associated spur or bevel gears. Apply a light, suitable gear lubricant to the teeth and recheck mesh after a short run-in period. The pinions help preserve drivetrain timing and reduce noise or binding caused by worn or mismatched pinions.

Use this set as a direct service replacement when diagnosing drivetrain issues on compatible Hirobo helicopter models, and always validate physical dimensions before installation.