However, one change we made to the front axle was upgrading to the Dynatrac Free-spin kit. This replaces the costly unit-bearing and upgrades to a rebuildable hub and spindle. Also the Dynatrac kit has the tone ring and speed sensors included in the new hub and spindle so that the ABS brakes and computer are all correct and compatible. We can now run selectable hubs on the front axle. Selectable hubs mean the front axle is not turning when driving on the street, and though we are running Warn premium hubs for now, we are going to test one of the first sets of Dynatrac's own Dynaloc selectable hubs on the JK in the future, so watch for a complete install on those in an upcoming issue.