The Quadra-Trac name is used on a variety of Jeep full-time 4WD systems. It was available on several Jeep vehicles over a span of years. Often the name Quadra-Trac name was used to refer to the full time 4wd system even though many of the systems operated differently and were even made by different manufacturers. The Borg-Warner 1305 and 1339 gear case were the original systems to carry the Quadra-Trac name.
The first version used the Borg-Warner BW1339 transfer case and was produced from 1973 to 1979 and was used in the following applications.
1973-1979 Jeep Wagoneer (SJ)
1973-1979 Jeep Cherokee (SJ)
1973-1979 Jeep Gladiator
1976-1979 Jeep CJ-7
The aluminum case, chain drive system introduced in 1973 was found in the above listed vehicles behind a special AMC version TH-400 automatic. The system operated using a differential to split/shift torque from front to rear automatically. The systems came equipped with a vacuum operated differential lock that would allow full 4wd.
The two transfer case models used were separated by the low-range option. The Borg-Warner 1305 offered 4WD Hi modes in full-time or part-time (locked) modes only. The 1339 offered a full-time and part-time low range of 2.57:1 ratio.
Both the 1305 and 1339 used off-set yokes that exited on the passenger side. It can be easy to spot a Jeep equipped with a Quadra-trac system since the rear differential is off set to the passenger side.
In a CJ the vacuum lock switch was located in the dash glove box and the low range selector was a small lever located on the center hump.
The low range option on the 1339 was achieved with an addition of a planetary gear reduction system added to the rear of the input shaft on a 1305. A 1305 could be converted to a 1339 with the addition of the planetary gear system.
A well known issue that occurred with these units was a stretching chain that would cause play in the drivetrain and can result in a complete failure. Proper maintenance can extend the life.
Milemarker made two upgrade options for the BW1305 and the BW1339. One option replaced the differential with a spool, this provided a 4wd lock from front to rear and with the addition of front lock-out hubs the Jeep could run in a 2wd mode. This helped with fuel economy and driving quality. The other option from Milemarker was a 16% overdrive.
Both options from MileMarker are still available from a variety of 4wd parts vendors.
The original Quadra-trac system is becoming a scarce item and parts are becoming hard to come by. Often many of these systems were neglected and abused.
There are a few options for those looking to remove their Quadra-trac system in their CJ. A Dana model 20 transfer case can be installed, this requires a few changes though. The biggest changes require the rear transmission output shaft to be replaced with a Dana 20 output gear and the rear axle needs to be replaced with a centered differential version.
Novak makes a Dana 18 conversion kit which allows a Dana 18 to be installed in place of the Quadra-trac. This maintains the offset output and provides the Jeep a solid transfer case.
Into the future..
There were many varieties of the Quadra-trac after 1980, none are covered in detail in this article. The 2nd version replaced the Borg Warner system with New Process Gear system in 1980. The NP219 transfer case and was produced from 1980-1982 (Jeep Wagoneer) and the NP249 was used from 1993-1995 (Grand Cherokee). The New Process system was chain driven with a viscous limited slip coupling that connected the front to the rear drive shafts. The system offered 4wd hi full-time, part-time, and 4wd low part-time.
In 1996 New Venture Gear started production of the 249 transfer case and it was renamed the NV249. The NV249 introduced a low range lock that provided a hard gear connection to front and rear. The NV249 could be found in the Jeep Grand Cherokee and Jeep Cherokee.
The Quadra-Trac systems were never found in any of the Jeep Wrangler models from YJ to JK or in a CJ-5.
Spotting a Quadra-trac equipped CJ-7 is pretty easy.
No lockout hubs – a Quadra-trac Jeep will not have lockout hubs unless a conversion was installed.
Rear axle offset – the rear axle in a Quadra-trac equipped Jeep will be offset to the passenger side. Easily spotted from the rear.
No 4wd shifter – there will be a totally open hump in the center of the Jeep’s interior.
Ominous looking switch in the glove box – don’t be afraid.