TRX-4 Front Brass Knuckle Inner Arms TRX4021BX by GPM  [TRX4021BX]

Brass inner knuckle arms built for TRX-4 trail rigs

This brass upgrade replaces the standard inner front knuckle pieces on TRX-4 scale crawlers with heavier, precision-machined units aimed at consistent fit and extra ballast. The machined finish helps maintain smooth knuckle pivot rotation while the added mass improves low-speed stability. These components are for RC models only and are not for use on real vehicles.

Fitting guidance: the brass inner knuckle locates into the knuckle inner case and uses the supplied stainless steel fasteners for secure assembly. During install verify bearing clearance and alignment, and use a moderate threadlocker on the button head screws to reduce the chance of loosening during vibration. Typical hex drivers cover the required screw sizes.

Included hardware and parts: inner part front knuckle 2pcs, stainless steel round head screw 3x16 2pcs, stainless steel round head screw 2.5x3 6pcs, stainless steel button head screw 2.5x8 4pcs. Each arm provides about 50g of external weight potential so you can dial in front bias for better traction on technical obstacles.

For TRX-4 drivers wanting added front ballast without changing ride geometry, this brass inner knuckle set is a simple upgrade that influences traction and steering feedback.