RC Helicopter Shaft Collar 2.6 x 4 x 12S - Hirobo HI2521080  [HI2521080]

This Hirobo HI2521080 collar is an RC-scale shaft collar intended for use in helicopter general parts and maintenance. The item designation 2.6 x 4 x 12S describes the nominal sizing model builders use to match collars to shafts and small linkages.

As a functional part, the collar provides axial retention and helps keep small assemblies aligned during flight and ground handling. Fit it where a compact axial stop or locator is needed in rotor or transmission subassemblies.

Fitting is straightforward: slide the collar onto the shaft at the chosen position, align with mating components, and secure following the original assembly method. Check the fit after installation and perform a low-speed spin test to ensure there is no binding or unwanted play.

For tuning, the collar is a small but precise locating element that can influence minor shaft endplay and alignment. When adjusting rotor spacing or gearbox stacks, reposition or replace collars to recover correct stack height and reduce lateral movement without altering primary components.