dam was it made of tinfoil lol
Use Nord lockwashers.
http://www.mcmaster.com/#nord-lock-washers/=nne0bi
I've literally never had a single one come loose on me, and neither has anyone I've ever know who uses them. Just follow the installation instructions properly and you'll be good to go. They don't 'wear out' like most (every?) thread-locking nuts will.
Thanks for the links JamesCH, nordlock washers and copper locking nuts are ordered. Its a bit of over kill but better safe then sorry. According to Nord Lock site the serrated nuts might be the issue, seams like they aren't as good under vibration as i thought.