Problem solved, but only temporarily. That contactor isn't going to last, and when it fails, there's a good chance that it will fail with the contacts welded closed. There's a reason mfgrs make a separate design just for starting.
Start contactors are designed to repeatedly make/break extreme currents; master contactors are only expected to *carry* extreme currents, with the assumption that breaking extreme currents would be a rare, emergency function. Start contactors have much stronger (higher current) coils and much stronger return springs, so opening/closing happens faster to minimize arcing. More: https://www.google.com/search?q=star...obile&ie=UTF-8