LOSI Promoto-MX Motorcycle +30mm Extend Swing Arm Kit by GPM MX3057  [MX3057]

Extend swing arm kit for Promoto-MX

This GPM MX3057 kit is an RC-scale upgrade composed of an extended swing arm, a longer pull rod, and a matched chain designed to replace the stock Promoto-MX motorcycle rear linkage. The components are machined from aluminum and increase rear wheelbase by 30mm relative to the stock arm, offering a straightforward way to alter chassis balance on LOSI 1/4 Promoto-MX models.

The kit’s role is tuning-focused rather than cosmetic: extending the swing arm shifts weight distribution and rear traction characteristics, and the longer pull rod and chain are supplied to maintain correct geometry and drive alignment after the extension. Fitment requires removal of the stock arm and transfer of any required bearings and fasteners; basic shop tools are sufficient for installation.

Use this part when you want to change handling for higher-speed straight-line stability or to fine-tune traction response on hardpack tracks; verify model compatibility before installation and inspect chain alignment during initial runs.

This GPM MX3057 aluminum +30mm swing arm kit provides a direct hardware upgrade path for specified LOSI Promoto-MX platforms, supplying the longer pull rod and chain needed after extension and serving as a practical tuning option to adjust rear traction and stability on the RC motorcycle chassis.