Differential Assembly: Description and Operation

DESCRIPTION
The rear differential is a limited slip differential (LSD) incorporating outer plates, inner plates and viscous coupling with silicon oil. The spindle, which is an integral part of the rear drive shaft, is coupled with the differential side gear and viscous coupling (VC) by circlips.





A viscous coupling (VC) type LSD has been adopted so as to ensure safe and smooth transfer of increased power under various driving conditions. This VC type LSD features ease of turning while maintaining excellent stability when driving over slippery roads or when using engine brake, thus enabling engine power to be utilized efficiently. Smooth restriction of the differential operation of the left and right wheels results in improved running stability on bad roads, snowy roads, and also on muddy roads.
The VC type LSD adopts a "shaft to shaft system" in which the RH and LH rear drive shafts are coupled by a VC. This results in a compact structure with high performance.
The inside of the VC housing is formed by alternately combining the outer plates (the outer periphery of each plate engages with the internal spline of the housing) and inner plates (the inner periphery of each plate engages with the outer spline of the hub).
On the outer periphery of the outer plate, the spacer ring is fitted and set in position. On the inner plate, no positioning ring is used: The plate can be moved a certain amount on the hub spline in the axial direction. Sealed inside the housing is a mixture of high viscosity silicon oil and air. The housing is sealed by X-rings so that silicon oil will not leak into the rear final drive even when the pressure increases due to a greater difference in the rotation speed between LH and RH wheels.
The spindle (LH) which is integral with the rear drive shaft (LH) is coupled by the VC case spline, and is fitted to the side gear (LH) which is integral with the VC case. The spindle (RH) which is integral with the rear drive shaft (RH) is spline fitted to the side gear (RH). The end of the spindle is fitted by splines to the VC hub. No disassembling of the VC is allowed.

OPERATION





1. During normal straight-road driving where the right and left wheels run at an equal speed, the differential case and side gears rotate together, just as in conventional differentials. As a result, driving torque is transmitted equally to the right and left side gears.





2. When right and left wheels turn at different speeds. When a speed difference occurs between the right and left wheels, the VC housing and VC hub turn relatively at the same speed difference as that of the rear drive shaft. Because of the shearing force caused in the silicon oil, a differential torque is generated, which controls differential operation (idle rotation). For example, if the left wheel turns idle due to a difference in the road resistance, a speed difference occurs between the right and left wheel. Since the VC is installed between the right and left wheels, a differential torque is generated in the VC corresponding to this speed difference, and this differential torque is transferred from the left wheel to the right wheel. Accordingly, a greater driving force is transferred to the right wheel which is rotating at a lower speed.

SERVICE PROCEDURES FOR LSD
The component parts of LSD assembly are not available individually. Therefore, it is recommended to not disassemble LSD assembly.