Originally Posted by
Hawk man
Could this damage the spindle comes undone?
As disbrantjr said, the steel BB spindle is unlikely to be damaged by the softer aluminum crank arm. You really don't have much to lose but I'm betting the crank arm is ruined. This happens often enough that shops I've worked at used to keep generic left crank arms in stock. It's an economic repair if you aren't too picky about the crank arms matching side-to-side. FWIW, the torque spec for that crank arm bolt is usually around 30 ft/lbs. If you don't have a torque wrench imagine a 30 pound weight hanging off the end of a foot long wrench. It's more torque than I'd use if left to my uninformed judgement.