The best way to prevent ball joint is replace them often. I do mine every year as I have had numerous failures. I have since added limiter straps to my a arms to reduce the risk and the failures are few and far between.
To do this you need to go to you dealer and buy limiter straps from any snowmobile model. Mine are from a Yamaha nytro. Simply bolt them to your upper and lower a arm very tightly and this will prevent the ball joints from pulling apart. If they do, it will be limited and likely not come all the way out. Enough to get you home at least.
Refer to picture.
Also if your ball joint does ever fail on you, now worries. Straps or not, if you have a winch, wrap that sucker around both arms and suck it in. There is no way it will come apart on you and you can get home in a safe manner. Ratchet straps also work or a whole package of zip ties and duct tape.
