What's the diff ?
( a matter of a pinion, some would say )

    Differentials are simple components that present complications to many people including motor vehicle repairers.

    One of the reasons for this is that the results of differential repairs, unlike repairs of other  components of the vehicle, are not usually apparent until the job has been fitted and road tested.

HOW DOES A DIFF WORK ?

The intention of most differentials is to:

• Multiply the available torque (Gear reduction)

• Apply engine power to rear/front wheels

• Allow the wheels to turn at different speeds when cornering

Engine power is provided through a drive shaft, (tail-shaft) in rear wheel drive applications and through an east west mounted engine & transmission in front wheel drive applications.

The pinion is supported by pinion bearings, (photo on left), whilst the crown-wheel and carrier are supported by the carrier bearings, (photo on right). The planetary gears are mounted within the carrier (hemisphere) in a cluster of 4 or 6, thus allowing the left & right axle to turn at different speeds whilst accepting engine torque.

When driving in a straight line the planetary gears and carrier, (or hemisphere), revolve as a unit, but when a corner is negotiated the two axle (or side) gears are allowed to turn at different speeds.

Front differentials in 4WD vehicles receive torque via the transfer case which is normally attached to the rear of the gearbox.

Front wheel drive vehicles do not have a tail-shaft as all the application is within the engine and gearbox, (transmission), assembly.

ADJUSTMENTS AND CLEARANCES ARE IMPORTANT TO RELIABLE DIFF OPERATION.