(I have seen many universal joint failures in my time . The latest one I know of was my frind's almost new Champion trike. Those are Toyota universals I am told and certainly are up to the task. There are a multitude of reasons why a U-joint might go bad. Some are lubed for lifetime (whatever that is!) and others like the Motor Trike happen to use a Ford universal and the rear one does require lubing. It is an easy chore to pull the driveshaft on a Motor trike for lubing and inspection. In summary I have to say that no one can be absolutely sure when a u-joint is going to go bad. It IS of course prudent to inspect it for any slack or unusual problems. Even then you could drive 100 miles later and have one fail. Maybe that why most auto stores carry a fair selection in stock...ya think??