Hirobo HI2521061 Collar 5 x 8 x 2.5 RC collar part  [HI2521061]

Collar for RC helicopter linkages

This Hirobo collar is a small RC-scale retention part sized 5 x 8 x 2.5 designed to locate and secure linkage pins and shaft interfaces in helicopter assemblies. Its role is purely mechanical, serving as a spacer and retaining element where compact, repeatable positioning is required during setup or repair.

Installation notes: confirm the collar matches the shaft and hole diameters, slide into place on the shaft or pin until it seats evenly, and verify free movement of adjacent linkages before securing any retaining screws. Check axial alignment after installation to avoid introducing binding in cyclic or pitch linkages.

Tuning role: collars of this size are useful when adjusting endplay or fine-tuning control geometry; small changes in collar placement can alter lever lengths by fractions of a millimetre, which matters for precise trim and neutral positions.