mr. whiteangel
Brake discs are made up of duplex steel or similar material. cast iron ki hon to har 2000 km pe change kerani paray gi.
this is crevice plus stress assited corrosion. barishon ki waja say huwee hai. drive around theek ho jai gi.
tell ur uncle to keep em dry.
but no wait. liana ones look quite deeply corroded.