Pedzisa mutsara unotevera: Nokuda kwa 1951, Mutual yakakwira zvikuru mitengo yayo yokushambadzira, uye mutsigiri wayo mukuru, Perfect Circle Piston Rings, akabvisa tsigiro yayo. Mutual pakupedzisira yakasarudza kurega kufukidza chiitiko chacho, uye kwakaratidzika kwenguva yakati kuti mujaho wa1951 hauzopfuudzwi paredhiyo. Mukuvamba kwaMay wa
1951, purezidhendi weSpeedway Wilbur Shaw akaita chibvumirano chomuminiti wokupedzisira chokuti WIBC ifukidze nhangemutange yacho, naSid Collins somutauri wenhau. Chimiro cheWIBC chakatevera icho cheMutual's, nehupenyu hwehupenyu pakutanga, kupedzisa, uye zvinyorwa zvenguva dzose munhangemutange yose. WIBC yakapa kufukidzwa kwayo kune anenge makumi maviri nemashanu mamwe maMutual akabatana.