Originally Posted by Dan Burkhart

Those "no turn" washers are vital. I strongly suggest you dig them out of the trash bin and put them back on.
The planetary gearing levers against the sun gear which is fixed to the axle shaft. The forces which propel the wheel forward are also trying to turn the axle backward. The power flow simply follows the path of least resistance. If the axle is not braced against rotation by means of the "no turn" washers at the least, or ideally by means of a torque arm, you may be powering up a hill one day when the torque suddenly finds it easier to turn the axle backward than to turn the wheel forward. This will cause your bearings to become mal-adjusted, and will be the beginning of many problems with your hub.

Dan Burkhart