Replacement Upper Arm Nut for TRF421X Chassis - Tamiya 9803565  [9803565]

Fitment and compatibility notes for TRF421X

This part is an RC-scale replacement upper arm nut intended for the TRF421X chassis and is identified as Tamiya 9803565. It serves as the pivot fastener that keeps suspension geometry stable while you make fine adjustments such as ride height and camber.

Compatibility is specific to TRF421X-series suspension assemblies as indicated by part reference 42391. When fitting the nut, begin threads by hand to avoid cross-threading, ensure mating surfaces are clean, and use the correct hex driver or wrench for final tightening. Avoid over-tightening to prevent damage to plastic or composite arm inserts.

The nut holds pivot position under load so alignment and setup remain consistent. Check it regularly after impacts and re-verify thread engagement when changing arms or other replacement items.