Up to Standards
- Author: Mike Weinberg, Contributing Editor
- Subject Matter: Transfer Case
- Unit: BW44-44
- Vehicle Application: Ram 1500 pickup trucks
- Issue: Conversion Kit For Plowing
Wet clutch pack uses ramp-and-ball system
Experience we gain from solving problems generated in the transmission repair industry sheds light on various common failures and allows us to see trends that provide new products to solve design issues.
From 2011 on, Dodge has offered Ram 1500 pickup trucks equipped with the BW 44-44 transfer case. The 44-44 transfer case is a computer controlled “active” full-time transfer case.
A wet clutch pack in the transfer case can split torque between the front and rear axles depending on the range selected by the driver. There is a 4WD low range that provides a 2.64-1 gear reduction for off-road use. A dash-mounted selector switch allows the driver to select five ranges, which include 2High, 4WD Auto (which can be used on dry pavement), 4WD Lock, Neutral, and 4WD Low. The shift selector switch feeds range selection to the Drive Train Control Module (DTCM), combined with input from the transfer-case mode sensor and input from the truck’s bus to determine if a shift is permitted within the design parameters.
If the shift command meets the software requirements, the externally mounted shift motor will shift into the desired range. The wet clutch is electromechanical design, using a clutch pack and a ramp-and-ball system to engage the clutch pack to send torque to the front axle when a slip is detected (difference in axle speeds) in 4WD auto range In the other 4WD ranges, the clutches are locked to achieve 4WD ranges. There is no mechanical lockup, and the clutch pack has to deal with all the torque transfer.
Herein lies the problem. Many customers in the snow belt and Canada are using this setup for snowplowing. Field reports show that the clutch pack cannot handle the abuse put on it by plowing snow or heavy offroad use, such as beach-driven vehicles.
The electromagnetic clutch with ball-and-ramp design has been around for a long time in the BW 44-05, 4406, and 4411. The 44-44 clutches have a narrower band of friction material than the aforementioned models, with a thinner pressure plate, to add more clutches to the pack. This works fine in vehicles that are not used for snowplowing or heavy offroad use on beaches, but cannot live under the stress of that usage.
One fix is to swap in a BW 44-45 transfer case, which is an electronically shifted part-time transfer case, which is a direct bolt in. The computers are the same in both, but nevertheless, this is a very expensive undertaking. To get around this, we have developed a kit to mechanically lock up the 44-44 in 4WD ranges to prevent future clutch failures. Removing the 4WD Auto mode means that the vehicle can no longer be driven in 4WD on dry pavement, with the plus side being that the driver can plow snow or beach drive to his heart’s content without clutch failure.
This kit, available next month, will cost approximately $800 and requires disassembly of the transfer case. Keeping your commercial customer on the road earning money from his vehicle is job No. 1.
Mike Weinberg is president of Rockland Standard Gear.