The most reasonably priced component used on the Cb400nc 1983 (d) Germany / Full Power Type 1 Front Brake Caliper is the Bolt,hex 6x10.
On this parts fiche the Piston is the most specified component.
The twenty-seven Cb400nc 1983 (d) Germany / Full Power Type 1 Front Brake Caliper component parts are all listed in this schematic.