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The Borg Warner QuadraTrac transfer case is an innovative transfer case as found in 1973-1979 FSJ and CJ7 Jeeps.
The Jeep QuadraTrac represented a number of firsts for Jeep and the 4wd industry. As had been the case since 1941, Jeep was driving the entire industry's transfer case technology at the leading edge. The QuadraTrac was the first transfer case supplied by Borg-Warner in a Jeep (all previous versions were Dana or New Process models). It was the first chain-drive transfer case to enter mainstream truck use and it was the first to have an aluminum case. It was released in the 1973 Jeep FSJ Wagoneer.
This unique transfer case had an integrated limited-slip differential much like an axle, that transfers power to the front and rear axles. A driver operated vacuum switch (usually located in the glove compartment) allows this differential to be locked at will.
The QuadraTrac has an aluminum case that splits laterally around its perimeter. Both front and rear output yokes are offset to the passenger side. The unit may feature a planetary reduction gearbox (as pictured, above) that is inline with the transmission output shaft.
The basic version of the QuadraTrac is the BW 1305. This transfer case did not have a low range. However there was an optional low range of 2.57 for the QuadraTrac available, being attained through a bolt-on planetary reduction unit. This unit as an assembly was designated as the BW 1339.
Two popular aftermarket upgrades to the QuadraTrac were offered by MileMarker. The first replaces the full-time differential unit with a part time spool. Then, the installer can fit the front axle with conventional lockout hubs for true part-time operation and its associated fuel, tire and geartrain savings. A subset of this MileMarker upgrade is the 16% overdrive feature, which can be added.
These transfer cases have their share of quirks, mostly related to the fact that no provision was made to compensate for stretch of the steel drive chain. The QuadraTrac was actually a pretty tough transfer case when well maintained.
As per the trend over the past few years, parts for QuadraTrac transfer cases are becoming increasingly difficult to find. Rebuild kits are currently unavailable through Novak.
Repair parts can be a bit rare.
Those hoping to repair their QuadraTrac often opt to swap in a Model 18 transfer case. Our Kit #124 makes this worthwhile upgrade possible. The Dana 18 makes for a great replacement transfer case for the Borg Warner. It has the same offset, drop and yoke size, allowing for the retention of the front and rear axles. The strength of the Dana 18 if properly maintained is very adequate for even the heavier Jeeps and their V8's.
The QuadraTrac uses a special fluid due to its use of a special limited-slip friction cone. Individuals filling their transfer case should be aware that it is not the conventional oils or ATF used by other transfer cases. Many claim success using 30 weight oil with a limited-slip additive.
The QuadraTrac was only found behind the TH400 automatic transmission. No other transmission is compatible with the QT.
It should be recognized that the 1339 was a revolutionary unit, with the majority of modern transfer cases today being based on many of its theories, with the industry learning important things from its strengths.