Broke the left crank off my Schwinn

I have a 26" Schwinn Cimarron Comfort Bike that I've been riding to work. I'm getting ready to order a motor in the next month or so, but this morning on my way to work the left crank came off my bike. I walked the rest of the way to work and brought the crank to my desk to take a look at it. The nut seems to be ok and I'm going to check the threads on the bike at lunch. If the threads on it aren't too bad is it safe to put it back together with some locktite or something or do I need to buy a new crank set? Can these nuts back themselves out without causing damage? Thanks

Roger

IM ASSUMING YOU HAVE A THREE PIECE CRANK???

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MEASURE ONCE AND CUT TWICE.......WAIT A MINUTE

Yes, it is a 3 piece crank and the left crank came off at the hub.

You'd likely be better off buying a new left crank arm. What happened to your old one is a pretty common occurence, and once it wobbles enough to work its way off, the square mounting hole is usually mashed out of tolerance, and it will just work itself off again. A new cheap arm should cost between $15 - $20. Make sure you get the same length as the old one. Put a bit of grease on the spindle threads and tighten it on. Or if your bike shop is cool they will install it for just a bit more.
Cheers, Geoff

oil it up up with a bit of lock tight if its real bad chase the threads with a file. good luck

I've ridden it two work three times since I put the crank back on and it hasn't tried backing out on me yet. I'm going to keep my 14mm socket in my toolkit on the bike and keep an eye on it for a while. If it happens again I'll replace the crank.

It happened again today on my way to work so it's time for a new left crank. I'm going to repair this one for just riding, but I'm picking up a single speed cruiser tomorrow night to mount an engine on. Now if I could only make up my mind if I want a 2 stroke china girl or the frame mount 4 stroke from bicycle-engines.com or fiveflags motorbikes.com.