Hirobo HI2521081 Collar for RC Helicopter Shafts 4 x 5 x 6.5S  [HI2521081]

Overview of the shaft collar

This Hirobo HI2521081 collar is made as a radial clamp to keep axial position on helicopter shafts in RC models. The part number includes the nominal measurements so users can confirm whether the size suits their shaft before installing. It acts mechanically to stop axial movement of gears, bearings, or rotor parts while you perform bench work or maintenance.

To install: verify the collar matches your shaft diameter, slide it into place, and secure with the recommended hardware or method. For consistent performance, clean contact surfaces and recheck endplay after tightening. Use the collar to maintain alignment while trimming or tuning blade pitch and spindle placement.

Do not estimate torque values; consult your airframe or component maker's guidance to avoid damaging shafts or adjacent items. This product is intended only as a replacement or spare for RC-scale helicopters.