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by Bob Sheaves (former Jeep-Truck engineer)
JJ was to be a light, softly sprung vehicle that actually performed around as well as the then-current Grand Cherokee. It was to cost on the order of one quarter to one third less than the Grand Cherokee.
This was planned to go into production as a lower cost but still highly mobile vehicle for the third world countries and marketed in North America as a “beginner’s Jeep.”
Money was saved by using a conventional transfer case (the 2.5 Chrysler engine and 5 speed transaxle was lifted directly from the Plymouth Horizon and Dodge Omni), a fabricated frame (“toy-tabbed” for assembly - a trick that was proven out on the HMMWV body assembly), and minimal option availability (as I remember, A/C was not even an option).
It was designed to be 13 separate modules, assembled by suppliers, and practically snapped together at the assembly line — without needing electricity to snap pieces together.
The powertrain, lifted from the Chrysler parts bin, was turned north-south (from east-west). It worked out quite well, for what it was. No separate transfer case, a short, lightweight powertrain....the powertrain was turned 90 degrees to get the shortest possible single-speed “transfer case” AWD system possible. As I recall, from the front of the crank pulley to the rearmost portion of the transfer gearing housing, the length was about 26 inches, versus the 2.5 AMC 4 cylinder, Spicer 3 speed transmission, and an experimental single speed NP AWD transfer case length of 31.5 inches.
We actually had a too short length. The front axle propshaft for JJ was only 14 inches long from center to center of the U-joints. (It had a straight axle front and rear, but not like any of you are thinking. We used a fabricated support housing for a Dana 27 aluminum independent front suspension carrier housing front and rear with exposed axle shafts.)
For a Suzuki Samuri-type vehicle, it could beat the pants off anything in its class.
[One issue is that] it was determined that the vehicle was too advanced and that there would not be sufficient market to justify the cost for setting up a totally new plant, considering the Grand Cherokee was to debut at the same time. Marketing determined that the money was better spent on the BR (Dodge Ram) and second-generation Grand Cherokee programs.
Ultimately, it was killed as it could not make it over the Rubicon unassisted and wasn't considered a true Jeep by the majority. The JJ could not traverse the Rubicon Trail completely without a towrope on one steep section. It lacked the tire static loaded radius to get across one particular technical challenge. That was the only failure to complete the test. Evan Boberg and I disagree on this point, as I feel it was a true Jeep, same as the original MBs were. A stock MB a friend of mine had was unable to cross the Rubicon trail without assistance.
We knew that we might run into this issue, but, due to the cost restrictions and suspension restrictions, we decided that we would try it with a 29 in tall tire, instead of a 31 inch tire. The 31 just would not fit without hitting and tearing up the front fenders and wheelhouse. I still firmly believe JJ would have sold well, primarily due to the two-thirds cost of the Wrangler. JJ still outperformed the Rocky, RAV4, and Samuari. We just did not meet the target.
A total of 60 some vehicles were built as preproduction prototypes and all met the durability standards for the regular Jeep line, surprisingly enough (especially when you realize that, with the exception of the engine and transmission, literally everything else was new).
I believe the JJ could pass, easily, the requirements for Trail Rated badge. One of the differences is that, to drive the Rubicon trail, a vehicle must have sufficient traction and engine oiling capacity to climb a 100% grade (this means the highest naturally occurring grade of loose Type 3 soil, which is 45° from horizontal). Trail Rating and current military standards require a 60% grade (which is still steeper than what you can climb without an assisting rope, while walking upright).
Bob Sheaves and Evan Boberg both worked on the JJ and Grand Cherokee. Photo supplied by Mark Dayman. This was one of the second generation (production intent) mules, even to the
paint. John Kent was the executive engineer. Evan Boberg wrote that the idea came from Francois Castaing, VP of Engineering.
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