Hirobo HI2521066 Collar 6 x 8 x 3.5 RC shaft collar  [HI2521066]

Small RC helicopter shaft collar

This Hirobo collar is a low-profile accessory intended for RC-scale helicopter maintenance and setup. The 6 x 8 x 3.5 marking identifies the bore, outer diameter and thickness used to match small hollow shafts and link rods on model helicopters. It functions as an axial stop or locator to control shaft position and reduce unwanted endplay without affecting rotation.

Installation is straightforward: slide the collar onto the shaft to the required position and secure it by tightening the collar contact point until the fit is snug and the shaft motion is constrained. Check alignment with surrounding linkages and rotor components before final tightening to avoid binding. Because this is a model component, verify fit on your specific shaft before flight use.

In tuning and setup, this collar helps maintain consistent control geometry by keeping bearings and links in the correct axial location, which can improve repeatability during trimming and component replacement. It is intended for hobby model helicopter applications only.