GM Service Manual Online
For 1990-2009 cars only

The locking differential consists of the following components:

    • Differential case - 1 or 2 piece
    • Locking differential spider - 2 piece assembly only
    • Thrust block
    • 2 differential pinion gears
    • 2 differential pinion gear thrust washers
    • 2 clutch disc sets
    • Locking differential side gear
    • Cam plate
    • Locking differential side gear thrust washer
    • Locking differential clutch disc guides
    • Differential side gear
    • Differential side gear shim
    • Locking differential governor
    • Locking differential latching bracket and spring

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 1 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 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. You can accomplish full-lock through the use of a heavyweight governor mechanism, a cam system 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 retards a cam which, in turn, compresses the multi-disc clutch packs locking 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. The axle parts of the vehicles equipped with the locking differential are interchangeable with those equipped with the conventional differential, except for the case assembly.