A vehicular final drive chain path length compensation and adjustment system using an idler assembly which is moved in a prescribed geometry by a stiff system. The system and method maintains constant the chain path length during suspension travel. An idler arm assembly guides the idler assembly along an arc-shaped path, with displacement along this path determined not by a spring, but by a cam rotated by a trailing arm on the vehicle. The idler arm assembly allows for a simple static adjustment to compensate the chain path length for wear of components and tolerances in the vehicle assembly.