The transfer case is used to provide power flow from the transmission to the front axle. The transfer case also provides a way of disconnecting the front axle in order to provide better fuel economy and quieter operation when the vehicle is driven on roads where the four-wheel drive is not required. The transfer case provides an additional gear reduction when placed in low range. This is useful when driving in difficult off-road conditions.

The K3 models with single or dual rear wheels use the Borg Warner models 4401 or 4470 transfer case. Both of these transfer cases use a shift lever and a shift linkage in order to change the operating range. The models 4401 and 4470 are aluminum case, chain driven units with four modes of operation:

A planetary gear set provides the reduction gearing for the low range.

A floor mounted shift lever is used in order to select the operating range for the 4401 and the 4470 transfer cases. The indicator lamps on the floor console show the current mode of operation. The four wheel drive indicator lamp illuminates whenever the front axle is engaged. After selecting four wheel drive from the two wheel drive position, a slight delay for the front axle indicator lamp to illuminate is normal.

Two Wheel Drive Operation

When the transfer case is in the two wheel drive range, the torque flows from the input gear to the range shift hub and the main shaft, through the propeller shaft to the rear axle.

2HI to 4HI

The Borg Warner 4401 and 4470 transfer cases use an electro--mechanincal in order to provide smoother shifting. The system requires no maintenance or service.

The system consists of a control module mounted in a relay socket under the hood, and an electro--mechanical clutch inside the transfer case. The clutch replaces the conventional blocker wing. When energized, the clutch provides synchronization, resulting in a smooth shift. When the transfer case lever is moved to the 4HI or 4LO position, the current is supplied to the Timer Logic and Relay Module, which controls the application of power to the synchronizer and the front axle actuator.

Important: The front axle indicator lamp does not illuminate until the front axle is fully engaged.

Shifting from 2WD to 4WD causes the following sequence of actions to occur:

1. Operation of the shift linkage closes a switch in the transfer case. This switch applies current to the timer logic and relay module. The module applies current to the synchronizer and, after a delay of a few seconds, closes a switch that applies ground to the front axle actuator control input.
2. The electro--mechanical clutch provides smooth engagement of the front propeller shaft to the drive sprocket.
3. The front axle actuator uses an electric motor to engage the right axle output shaft to the front axle differential.
4. When the front axle is fully engaged, the actuator closes a switch causing the 4WD indicator lamp to illuminate and removing current from the synchronizer.

Four Wheel Drive High Range Operation

The torque flows from the input gear to the mainshaft the same as in the 2WD operation. The shift to 4WD causes the synchronizer sleeve to engage with the clutch teeth of the drive sprocket. This locks the drive sprocket to the mainshaft through the synchronizer sleeve. The torque is transmitted through the drive sprocket and the drive chain to the driven sprocket and the output shaft. The torque then flows through the front propeller shaft to the front axle.

4HI to 2HI

If the shift lever is moved back to the 2HI position, the operations in the preceding steps are reversed. The actuator motor operates in the opposite direction to disengage the right front axle from the front differential. This opens a switch extinguishing the 4WD indicator lamp.

Four Wheel Drive Low Range Operation

When the transfer case is shifted into the 4LO position, the torque flow and the operation is similar to the 4HI range, except that the range shift hub engages the planetary carrier. The planetary gear set then provides a gear reduction to the front and the rear axles.

Identification

The Borg Warner transfer cases have an identification tag attached to a bolt on the extension housing. The tag provides the transfer case model number, the serial number, a build date, and a low range reduction ratio.