The differential redirects power from the engine and transmission that has been transferred through the driveshaft to the driving wheels. At the same time the ratio of the differential gears takes the high rotational speed of the driveshaft and transforms it into a slower but more powerful force at the wheels. The other main purpose of the differential is to allow the inner and outer wheels to rotate at different speeds during cornering.
Differentials come in three basic types, which all have a different effect in low traction situations:
Fully Open Allows full torque and rotation to be transferred to the wheel with lowest traction, while the highest traction wheel can be stationary.
Limited Slip (LSD) Maintains a limited amount of torque and rotation to the highest traction wheel, so that both wheels will rotate at all times.
Locker Type Maintains equal torque and rotation to both wheels under all situations. Both wheels travel the same speed and distance during corners, which causes tyre slippage.
For correct operation and to extend the life of the differential it is vital that all four wheels have the same size tyres and their air pressures are correctly maintained. This is especially true on 4WD vehicles. Oil changes are recommended on differentials every 60,000 kilometres, and LSD Oil Additives should be used where applicable to smooth the operation of the differential clutches.
The fitting of differential lockers is recommended for off road situations. Air Lockers, Electric Lockers and Mechanical Lockers are all available. Depending on the use of the vehicle it may be appropriate to fit a different gear ratio to the differential from what is standard, and ratios to suit the specific needs can be supplied.
Shane’s Automatic Transmissions dynamically spin test remanufactured differentials to check operation and for running in purposes.