Hirobo HI2521102 COLLAR 5 x 8 x 3.5 shaft collar for RC helicopter parts  [HI2521102]

RC helicopter shaft collar

This HI2521102 collar from Hirobo is presented as an RC-scale replacement part within the helicopter general-parts group, identified by the stamped 5 x 8 x 3.5 marking. It is intended as a small mechanical collar used in model helicopter assemblies to help locate and retain rotating shafts or spacers without implying any compatibility beyond the manufacturer's general parts category.

In practical bench work the collar functions as a positional element: slide it onto the appropriate shaft location and secure the surrounding hardware so axial play is controlled. Because this is a component-level accessory, installers should verify fit on the target shaft and use the correct fixing method already specified by their helicopter’s parts layout or service manual.

For tuning and maintenance the collar's role is straightforward — it can be used to adjust axial spacing between gears or bearings and to restore consistent shaft alignment after service. Keep the component free of debris and confirm rotational clearance after installation to avoid binding in the rotor drive or transmission train.