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A vehicle’s wheels rotate at different speeds, mainly when turning corners. When cornering, the inner wheel needs to travel a shorter distance than the outer wheel, so for vehicles without a differential, i.e a kart, the result is the inner wheel spinning and/or the outer wheel dragging, and this results in difficult and unpredictable handling, damage to tyres and roads, and strain on the entire drivetrain.
A differential has three functions in your vehicle: to convert the power from the engine to wheels of the vehicle, to act as the final gear reduction in the vehicle, slowing the rotational speed of the transmission one final time before it hits the wheels and to transmit the power to the wheels while allowing them to rotate at different speeds.
The simplest type of differential is called an open differential. When a car is driving straight down the road, both drive wheels are spinning at the same speed. The input pinion is turning the ring gear and cage, and none of the pinions within the cage are rotating — both side gears are effectively locked to the cage. The open differential always applies the same amount of torque to each wheel. In dry conditions, when there is plenty of traction, the amount of torque applied to the wheels is limited by the engine and gearing; in a low traction situation, such as when driving on ice, the amount of torque is limited to the greatest amount that will not cause a wheel to slip under those conditions. So, even though a car may be able to produce more torque, there needs to be enough traction to transmit that torque to the ground. If you give the car more throttle after the wheels start to slip, the wheels will just spin faster. A strange but informative video to explain this:
The open diff is fine for the general road user but drivers that engage in Off Road Challenge Events the locking Diff is a better option. Please see our Locking Differential section for more information on the locking diff products we have available.
For the gentle Off Roader or for those drivers who often drive on low traction surfaces the Limited Slip differentials may be a preferable option. Please see our section on Limited Slip diffs for further information.
We are able to offer a wide range of differentials to suit your vehicle and your application. The diff can be supplied as a rebuilt assembly or we just supply the diff centre for DIY installation. We apply a core deposit when the diffs are sent out which is £125 or £200 (dependent on type), this charge is refunded when or if, the old unit is returned to us. For an explanation of the core deposit, please click here. We do not currently supply rebuilt Salisbury axles or diffs.