When a vehicle is turning each of its wheels travels along different paths because each path is a different length. Each wheel has to have an ability to rotate at different speed. In order to allow wheels to turn at different speeds a differential is used . Power is supplied from the engine via the transmission to a drive shaft which connects to the differential . A pinion gear is attached to the end of a drive shaft . This turns the ring gear . The ring gear surrounds a set of differential gears that enable the two rear axles to turn at different speeds. When the vehicle is travelling straight the left and right axle turn at the same speed. When the vehicle is turning the difference in rotating speed of the two axles is compensated for by the differential gears . Notice that the pinion gear turns at a different speed then the ring gear. The ratio between the two gears is called the axle ratio. By changing the axle ratio the torque multiplication and top speed is changed either increasing or decreasing them . Axle ratio is an important component of the transmission gear ratio . All the gear ratios between the engine and drive wheels determine how much power is actually applied to the wheels.The vehicle can be optimized for either heavy hauling and towing or normal driving and highway cruising but not typically both. You may also hear this described as final drive ratio. Open differentials are inexpensive, light weight and require little maintenance ,however the major disadvantage of an open differential is that engine’s power follows the path of least resistance.This means that in case one wheel has less traction then the other wheel . The engine power will go to the wheel with least traction. A way to limit this loss of traction is to limit the amount of independence between the two axles . This can be accomplished by a number of mechanical ,electronic or hydraulic systems which is known as limited slip differential . The benefit of limited slip differential is that the amount of power sent to the wheel with the least traction is limited so that the wheel with the most traction receives continuous power in order to get the vehicle moving . The disadvantage of a limited slip differential is the amount of power that can be transmitted to the wheel with traction is also limited . At cosmo car parts we have high quality drive shaft , CV axle shaft , wheel bearing and drive axle and we will hook you up with the right part at the best price .