I kept turning and turning and it would't tighten. Removed the bolt and surprise! the threads of the nut had stripped
Luckily, the bolt was OK but still had the problem of finding a nut. As any good home mechanic, I kept all my used pieces stored for emergencies and there was an uper arm of a Honda I had with a bolt, same diameter but different thread (fine) and same length. So I replaced the complete bolt and everything is in order now.