The Quadra-Trac name is used on a variety of full-time 4WD systems. The first version used the Borg-Warner BW1339 transfer case and was produced from 1973 to 1979. The next version used the New Process NP219 transfer case and was produced from 1980-1982. From 1993-1995 the New Process NP249 transfer case carried the name from 1996-1998 New Venture Gear started manufacturing it and it was renamed the NV249.
Quadra-Trac was the trade name for the Borg-Warner 1305 and 1339 gear case. It was a chain-drive system introduced in 1973 on the full-sized Jeep line which included the Wagoneer, Cherokee, and trucks behind the AMC-specific Turbo-Hydramatic 400 automatic transmission. CJ7s also received the Quadra-trac. This system included a differential to shift torque between front and rear which could be locked with vacuum. The Borg-Warner 1305 offered only 4WD Hi modes in full-time or part-time (locked) modes, while the 1339 offered a full-time and part-time low range of 2.57.
The Jeep Quadra-Trac was differentiated from the open "New Process" Gear NP203 used by Dodge, General Motors, and Ford in that it included a center limited slip differential feature, in this case a clutch pack.
Applications:
- Jeep Wagoneer (SJ) 1973–1979
- Jeep Cherokee (SJ) 1973–1979
- Jeep Gladiator 1973–1979
- Jeep CJ-7 1976–1979
The Borg-Warner system was replaced with a "New Process Gear" NP219-based chain-driven system in 1980 The NP219 Quadratrac transfer case was used in full-size Jeeps from 1980 through 1982. It offered the following modes: 4HiFT, 4HiPT, and 4LoPT. In full-time 4WD High a viscous limited-slip coupling is used between the front and rear output shafts.
Applications:
- Jeep Grand Wagoneer (SJ) 1980–1982
In 1993 Jeep introduced Quadra-Trac on the Jeep Grand Cherokee using the NP249 transfer case. The transfer case utilizes a viscous coupler which provides smooth and efficient four-wheel drive operation on dry surfaces. When a differential in speed occurs between the axles, heat buildup causes the viscous coupler to transfer power to the slower axle. It is similar to several passenger car systems, but with a low-range gear for serious off-roading. NP249 transfer cases used the viscous coupler to transfer power in both high and low ranges.
Applications:
- Jeep Grand Cherokee (ZJ) 1993–1995
In 1996 the NP249 was replaced with the New Venture Gear NV249 transfer case which added a low-lock capability, meaning a hard gear transferred power in 4LO (front and rear drive shafts are locked at same speed in low range).
Applications:
- Jeep Grand Cherokee (ZJ) 1996–1998
Read more about this topic: Jeep Four-wheel-drive Systems