GM Service Manual Online
For 1990-2009 cars only

The locking differential consists of the following components:

    • Differential Case
    • Differential Pinion Gears and Thrust Washers
    • Differential Cam Unit and Clutch Disc Assembly (Left Side)
    • Differential Side Gear and Clutch Disc Assembly (Right Side)
    • Differential Side Gear Thrust Washer (Left Side)
    • Differential Side Gear Shim (Right Side)
    • Locking Differential Governor Assembly
    • Locking Differential Latching Bracket Assembly

The locking differential allows for normal differential function as indicated in the standard rear axle description. Additionally, the locking differential uses multi-disc clutch packs and a speed sensitive engagement mechanism that locks both wheels together if one wheel spins excessively during slow vehicle operation. Under light loads, the clutch plates alone tend to lock the axle shafts to the differential case, and therefore locking to each other. This is due primarily to the gear separating the load developed on the right clutch pack. This induced clutch torque capacity resists motion between the side gear and the axle differential case. The differential allows the wheels to turn at different speeds while the axle shafts continue to transmit the driving force. Heavier throttle application will cause an axle speed difference. This action starts the full-lock feature of the unit. Full-lock activation is accomplished through the use of a heavyweight governor mechanism, a cam gear unit and a multi-disc pack. The flyweights on the governor mechanism move outward in order to engage a latching bracket whenever the wheel-to-wheel speed varies by approximately 100 RPM or more. This action locks the cam plate, which expands the cam gear unit and compresses the multi-disc clutch packs on each side of the differential which locks both of the side gears to the case. The 100 RPM wheel-to-wheel speed allows for cornering with the differential lockup. At vehicle speeds above approximately 32 km/h (20 mph), the latching bracket overcomes a spring preload and swings away from the flyweights. At this vehicle speed or greater, the differential is designed not to lock since added traction is generally not needed.