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AWD Transfer Cases

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  • AWD Transfer Cases


    Borg Warner - BW1372/4472
    This is the stock transfer case found in all Syclones and Typhoons from the factory. They are virtually identical with the exception of the output shaft and tailshaft extension. The 1372 found in the Syclone used a 27 spline output shaft where as the 4472 found in the Typhoon used a larger 32 spline output shaft. The 1372 could also be found in the Astro/Safari Vans from Chevrolet and GMC retrospectively, as well as the 1991 Oldsmobile Bravada. The 4472 can also be found in the 92+ Oldsmobile Bravada. This transfer case was utilized until 1998, however the 96-98 versions are slightly different from the earlier models and are not direct bolt in without changing some parts, mostly external.

    New Venture Gear - NV120
    Found in the Trailblazer SS, this is a single speed, full-time AWD transfer case that incorporates a front/rear drive differential carrier assembly.

    • The front/rear drive differential carrier assembly is an open differential in the transfer case that is always sending torque to both the front and rear axles. The front/rear drive differential carrier assembly is a torque-biasing devise that senses torque and multiplies it to the other wheel, so if 1 axle is on a low friction surface and loses traction, the front/rear drive differential carrier assembly applies more torque to the other axle, such as if the rear wheels are on ice, more torque is applied to the front axle, and vise versa.

    • This is a true full-time system since it is always active with torque split between front and rear axles so torque adjustments occur instantly and smoothly.

    • The ratio of front/rear drive differential carrier assembly application is split with 33 percent to the front axle and 67 percent to the rear axle under normal conditions, but since the system is torque biased, that ratio can range from a more balanced 45:55 split up to a 25:75 split depending on road conditions and driver demands.

    The front/rear drive differential carrier assembly uses helical gearing in a planetary arrangement. There are no clutches or preload springs. Under a no-load condition, it differentiates freely similar to an open differential. When torque is applied, thrust forces generated by the helical gearing create friction and resist differentiation resulting in limited slip capability. These forces act to drive the ring gear and sun gear either together, during coast torque, or apart, during drive torque. Thrust washers with controlled friction surfaces react against the separating force and create friction to oppose the relative motion. It does not require differentiation or wheel slip to properly distribute torque. The locking capacity of the differential is a result of the gear design. Therefore, as long as it transmits torque and differentiates, it is operating properly. The front/rear drive differential carrier assembly is a non-serviceable assembly and must be replaced with a new assembly if damage is suspect.

    The following actions occur because of the front/rear drive differential carrier assembly:

    • If the vehicle is on a hoist, the front propeller shaft can be rotated by hand.

    • The vehicle cannot be driven if 1 propeller shaft is removed.

    • Operating the vehicle on a hoist can damage the front/rear drive differential carrier assembly pinion gears, by over-spinning.

    • Operating the vehicle with 1 propeller shaft removed causes over-spinning of the front/rear drive differential carrier assembly pinion gears.

    To prevent damage to the front/rear drive differential carrier assembly, DO NOT:

    • Tow with only 2 wheels down

    • Drive without 1 propeller shaft

    • Drive with a donut spare for an extended period of time

    • Operate the vehicle on a hoist to diagnosis the driveline components

    New Venture Gear - NV149
    Found in 2002+ GM Products like the Cadillac Escalade, GMC Denali and Chevrolet Silverado SS

    Borg Warner - BW4485
    Morgan - ISTR Executive Director

    93 Typhoon #0180 || 93 Typhoon #1579 || 92 Typhoon #1068 || 07 Chevy Trailblazer SS
    52 Cadillac Series 62 Coupe || 85 Volvo 745 Turbo Diesel || 06 GMC Sierra 3500 4x4 CCLB SRW LBZ SLT || 01 Chevy Silverado 2500HD 4x4

    WTB : 93 Typhoon #1682

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