Front Differential
The front differential is mounted on the left side of the vehicle sump. The sump has a cast tube through it, which allows for the installation of the right axle shaft and separates the engine oil from the differential oil. The differential unit is secured to the engine sump with 4 bolts. The bolts pass through lugs in the differential housing and are secured into threaded holes in the sump. An "O" ring seal is installed to the housing and locates in the sump to provide a seal between the housing and the sump.
The housing comprises 2 halves with machined mating faces. See Fig 1 . When assembled, the iron housing halves are sealed with a thin film of Loctite 574 sealant and secured together with 12 bolts. The left housing is the carrier for all the rotating parts and the right housing is a cover to close the unit and a support for the right carrier bearing. A breather tube is installed to the housings. This allows a plastic tube to be installed and routed to a high point in the engine compartment, preventing the ingress of water when the vehicle is wading through water.
The left housing is installed with a drain plug and a filler/level plug. The level plug allows the unit to be filled with oil until it leaks from the filler hole, ensuring the correct quantity of oil is added.
The differential is a conventional design using a hypoid gear layout. This employs a hypoid bevel pinion gear and crown wheel, with the pinion offset below the center line of the crown wheel. This design allows for a larger pinion gear to be used which has the advantages of increased gear strength and reduced operating noise. See Fig 2 .
The differential comprises a pinion shaft and hypoid bevel gear, a crown wheel drive gear with an integral cage which houses 2 planet gears. There are 2 sun wheels located in the cage and pass the rotational drive to the drive shafts.
The pinion shaft is mounted on 2 opposed taper roller bearings with a collapsible spacer located between them. The spacer is used to hold the bearings in alignment and also collapses under the pressure applied to the pinion nut. This allows the nut to be tightened to a predetermined torque, which collapses the spacer, setting the correct bearing preload.
The pinion shaft has an externally splined outer end which accepts and locates the input flange, which is retained by the pinion nut. The opposite end of the output flange has an internal spline which provides positive location for the front drive shaft. The flange has an external "O" ring seal which seals against the front drive shaft shroud preventing the ingress of dirt and moisture into the splines. An oil seal is pressed into the left housing and seals the input flange to the differential unit. The pinion shaft has a hypoid bevel gear at its inner end which mates with the crown wheel drive gear.
The crown wheel drive gear is located on the carrier and secured with 10 bolts. The carrier is mounted on taper roller bearings located in each housing half. The bearings are press fitted into the housing and a spacer is located on the outside face to apply preload to the bearing.
The carrier is installed with a shaft onto which the 2 planet gears are mounted. The shaft is secured in the carrier with a roll pin. The sun wheels are located in pockets within the carrier and mesh with the planet gears. Curved plates are located between the carrier and the sun wheels and hold the sun wheels in mesh with the planet gears. Each sun wheel has a machined, splined, bore to accept the drive shaft. A groove is machined in the bore to locate the snap ring fitted to the drive shaft, providing positive drive shaft location.