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

Bevel pinion gear set overview

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 serves as the driven/driving interface on the motor-to-gearbox axis and is supplied as a matched set to maintain proper gear mesh in the tail or main transmission where bevel pinions are used.

Compatibility is established by the product path and model references, the set is intended to fit the common mounting patterns and shaft diameters used across Eagle/Freya/EX/SX components. Do not assume fitment on unrelated frames without verifying shaft size and spline count from vendor listings or original parts diagrams.

Installation notes and tuning role: fit the pinion set so that gear faces are parallel and backlash is minimal but not zero, check for smooth rotation by hand before power-up, and confirm alignment with any associated spur or bevel gears. During setup allow for a light, appropriate gear lubricant on gear teeth and recheck mesh after a short run-in period. The part's role in tuning is to preserve consistent 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.