Ok, the problem started a few days ago. I was dropping off the seat of a bench (2~ feet) and the left pedal came out of the crank arm. I walked it home, screwed it back in and then it was all good… or so i thought, i was outside today trying to jump up onto some bricks (my hopping sucks, but more on that later) and my pedal came off again. I would like to know, is it my pedal or my crank that is messed up.
the way the pedals turn has a lot to do with it, and thats why your wheelset can be on backwards. if it backwards, the pedal is constantly trying to unscrew, while if it is forwards it is constantly tightening.
Have you taken the wheel off the frame recently? Because you might’ve put it on backwards (yes, there’s a front and a back). Check to see that the left crank is really on the left side, and vice versa. If you have them reversed, when you pedal you can loosen your pedals and they can fall off, even if there’s nothing wrong with the threads. From your pics, it looked like the pedal threads were all right, but I couldn’t tell with the crank threads.