Jeep at Allpar: Cherokee to Wrangler, MA to Grand Cherokee
The core Jeep: Wrangler / CJ / Willys Quarter-Ton GP Truck
Development of the Bantam and Willys Jeeps
- Jeep MA and MB
- 1997 to 2006 Wrangler
- 2007 to 2010 Wrangler
- 2011-3 Wrangler (specs)
- Original Wrangler Unlimited
- 2007-2010 Unlimited
- 2011-3 Wrangler Unlimited
- Arctic Edition
- Jeep J8
The others
- Cherokee
- Comanche
- Earthroamer
- 2014 Cherokee
- Commander
- Compass and Patriot and Patriot EV
- Grand Cherokee: 1993-1998 • 1999-2004 • 2005-2010 • 2011-current • SRT • Maserati
- Liberty
- Wagoneer
Jeeps by year and category
- Jeep history
- Jeeps by year: 1959-61 • 1965 • 1975-76 • 1987-89 • Willys Whippet • Jeffery Quad
- Military Jeeps
- Development of the Bantam and Willys Jeeps • Jeep MA and MB • Jeep J8 (military/commercial Wrangler)
- Jeep RVs and campers
- Jeep Concepts:
- Dakar and Icon • Gladiator • JJ • Trailhawk
- Jeep XJ-002 Bolide
- Lower Forty, Grand Canyon II, Wrangler Overland, All-Access, Liberator II, and J8 Sarge
- Jeep Shows and Events:
- Mopar Underground at Moab
- Airpark Jeep Jamboree: 2010 • 2011 (also see our general car shows and events page)
Jeep Reviews at Allpar
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Quadra-Trac II
Launched in 1999 on the Jeep Grand Cherokee, the Quadra-Trac II transfer case normally sent most of the power and torque to the rear wheels. The moment a wheel lost traction, a gerotor pump applied hydraulic pressure to a multi-disc clutch pack, sending power to the front axle.
The gerotor pump used a rotor driven by the front drive shaft and the case by the rear drive shaft, creating a pressurized oil flow to the clutch pack in proportion to their speed variation. Clutch discs were alternately splined to the front and rear drive shafts. Because Quadra-Trac II could immediately pressurize the clutch pack, it had a faster response than a viscous coupling. (Quadra-Trac II’s low range had a 2.72:1 torque ratio and fully locked the center differential).
A similar pump was incorporated in the Vari-Lok differential; power transfer was therefore proportional to wheel speed difference rather than torque difference. By avoiding the need to pre-load the differential to assure torque transfer (so that normal use causes wear), the Vari-Lok could be virtually wear-free. Again, compared to systems using a viscous coupling (which also sense speed), Vari-Lok differentials responded more quickly and smoothly; and the pump response could be precisely tuned to driving conditions, enabling the use of this advanced system in the front axle as well as the rear.