Allen polaris is the krustys of the atv world you have an over ride button on the left hand grip that must be depresssed to get 4x4 in reverse. now hear is why polaris dosn't have a differential just a spool and differential action is preformed at the outer hubbs wit a sprag which is electronicly activated sprag's are a 1 way clutch for it to work in reverse it must be activated electronicly for reverse also you need to change the stinky hub oil on a regular basis as when it gets old the spags wont unlock properly and you will have hard steering good luck and don't forget to pimp it out