Lincoln F6TZ-7A039-F Transmission Extension Housing

Before attributing 4WD problems to the transfer case, eliminate any issues from engine, transmission, driveline, axles, brakes, hubs, or tires. Remember, driveline windup in 4WD mode can cause hop, skips, bounces, and delayed shifts, worsened by slightly different tire sizes or wear. If a transfer case overhaul is needed, consider replacement with a new or rebuilt unit. For DIY repairs, document disassembly, ensure cleanliness, pre-lubricate parts, test the case for abnormalities before reinstalling, and use the correct fluid. Avoid testing 4WD mode on the street; instead use dirt, sand, or mud.

Operationally, all transfer cases mentioned perform the same function. In 2WD mode, power is transferred from the transmission to the Input shaft of the transfer case, which then drives the output shaft through a non-functional planetary gear set. Shifting into 4WD mode locks a previously free wheeling gear onto the 2WD output shaft, connecting a second output shaft for the front driveshaft via a multi-row chain. This completes the transfer of power to the front wheels. Shifting into 4WD low activates the transfer case planetary gears for gear reduction of the 2WD output shaft, providing reduced gearing to both axles. The transfer cases differ in the mechanical means used for planetary gear reduction and shift mode mechanisms. Additionally, all transfer cases have an oil pump driven by the rear output shaft to maintain pressure during normal operation and towing.

To remove the transfer case, start by raising the vehicle and supporting it securely on jackstands. Drain the transfer case fluid if necessary. Disconnect the 4WD drive Indicator switch electrical connector or the shift motor harness electrical connector, depending on the model. Remove the speedometer cable and gear assembly if applicable. Disconnect the vent hose from the transfer case. Disconnect the transfer case shift rod link. Remove the skid plate if equipped. Unbolt the heat shield from the transfer case. Disconnect the front and rear driveshafts and tie them securely out of the way. Support the transfer case with a transmission jack. Remove the bolts retaining the transfer case to the transmission adapter. Carefully move the transfer case to the rear until the input shaft clears the adapter, then lower the assembly from the vehicle and remove the gasket between the transfer case and adapter. To install, reverse the removal procedure, making sure to check and fill the transfer case with the correct grade and quantity of lubricant. Tighten the fasteners to the specified torque.

Operationally, all transfer cases mentioned perform the same function. In 2WD mode, power is transferred from the transmission to the Input shaft of the transfer case, which then drives the output shaft through a non-functional planetary gear set. Shifting into 4WD mode locks a previously free wheeling gear onto the 2WD output shaft, connecting a second output shaft for the front driveshaft via a multi-row chain. This completes the transfer of power to the front wheels. Shifting into 4WD low activates the transfer case planetary gears for gear reduction of the 2WD output shaft, providing reduced gearing to both axles. The transfer cases differ in the mechanical means used for planetary gear reduction and shift mode mechanisms. Additionally, all transfer cases have an oil pump driven by the rear output shaft to maintain pressure during normal operation and towing.

If the vehicle is equipped with air suspension, turn off the air suspension system using the switch located in the area of the right kick panel. Raise the vehicle and support it securely on jackstands. Remove the transfer skid plate bolts, then take off the skid plate. Drain the transfer case lubricant. Remove the front driveshaft shield, followed by the front and rear driveshafts. Take out the torsion bars and the rear torsion bar support. For manual shift vehicles, disconnect the shift rod. Unplug the electrical connector from the vehicle speed sensor, and for manual-shift vehicles, also unplug the electrical connector from the 4WD indicator switch and the transfer case coil. For electric-shift vehicles, unplug the electric shift motor connector. Support the transfer case with a jack, preferably a special jack designed for this purpose, using safety chains or tie-downs to steady it. Remove the transfer case-to-transmission bolts. Make a final check to ensure all wires and hoses have been disconnected from the transfer case, then move the transfer case and jack toward the rear of the vehicle until the transfer case is clear of the transmission, keeping it level during this process. Once the input shaft is clear, lower the transfer case and remove it from underneath. Installation is the reverse of removal, ensuring to tighten the transmission-to-transfer case bolts to the specified torque.

The shift motor rotates the shift drum to engage the 4WD position, physically connecting the front drive gear to the rear drive output shaft.

Make a final check that all wires and hoses have been disconnected from the transfer case.