Tamiya 9803478 - Tensioner Nut for 42391 TRF421X TRF421 hop-up part  [9803478]

Tensioner nut for TRF421X

This replacement tensioner nut is a purpose-built RC-scale part intended for use with the 42391 TRF421X assembly. It serves a simple mechanical role: set and hold tension where the original nut locates, allowing repeatable adjustments during chassis setup and maintenance.

In practice the part is used to fine-tune drivetrain belt or linkage tension and to maintain consistent clearance in the affected assembly. Because it is a direct replacement-style component, installers should confirm fitment against the 42391 TRF421X mounting points before final assembly.

Installation is straightforward: position the nut on the designated threaded interface, adjust until the desired tension or clearance is reached, and verify smooth movement of the drivetrain or linkage through its range. After adjustment, recheck alignment and tension under rotation to ensure the setting remains stable.