This rear axle adjusting key is suitable for vehicles of the Citroën 11CV type from model year 1936. The tool supports adjustment and securing of components around the rear axle. It offers a matching shape and dimensions for use within the suspension and drive system. The key allows removal and installation of parts without damage to surrounding elements. It is usable in maintenance and repair workshops for inspection and correction of rear axle settings. The design focuses on functional handling and defined positioning during service tasks on classic vehicles, with emphasis on reliable engagement on the relevant contact surfaces.