Go Kart Forward Neutral Reverse Gearbox 80 Series Product Description (1) The diameter shaft is 16 mm (2) It is reverse-reducer-differential group (3) the ratio reduction of the reducer is : Forward speed ratio : 1:1.3 Reverse speed ratio: 1:2.6 (4) It have three position : forward , stop and backward (5) When you action the reverse movement , the vehicle will reverse .