Abstract: A limited slip differential gear assembly has a rotating housing containing meshing spur gears each turning a gear element which is externally helically toothed. Each gear element meshes with its own externally-toothed gear member which has a larger diameter and drives one of two output shafts between which differential movement is to take place. The meshing helical gear teeth have the characteristic that the efficiency of drive transmission in opposite directions is different and this provides the limited slip. As the axes of rotation of all rotating parts of the assembly are parallel, reduced constructional and operating costs result.