Tamiya 9803567 - Damper Piston 42391 Compatible with TRF421X  [9803567]

Technical Notes on the Damper Piston

The damper piston supplied as part 42391 is the Tamiya spare intended for TRF421X shock assemblies fitted to Tamiya scale RC cars. As the internal flow metering component, the piston influences oil passage through the shock and thus has a direct effect on damping response and rebound behaviour when matched with suitable oil and shock length settings.

This item is provided as a replacement for maintenance or tuning of the TRF421X suspension; purchasers should confirm the 42391 part reference against their shock parts list to ensure compatibility. When carrying out a rebuild, inspect the piston faces and shock shafts for wear and replace any degraded seals or spacers following the TRF421X service routine.

Practically, changing pistons or altering piston orientation adjusts internal oil flow and can be used to tune mid-speed and low-speed damping behaviour without changing spring rates or the shock body, making piston swaps a useful tool for progressive setup refinement.