38” TSL tires, mounted to Pro Comp Rock Crawler steel wheels

Project Gumby was destined to be different from the beginning. The owner had chosen axles, tires, and rims, but the suspension and wheelbase was up in the air. The 38” TSL tires were mounted to Pro Comp Rock Crawler steel wheels. The steel wheels were fitted with DIY bead-locks with a 3.75” backspacing. Once the tires and axles were under the jeep, it was obvious that the wheelbase had to be extended. Cutting the sheet metal just to create space was not an option to the owner, so we decided to move the stock wheel opening toward the rear.

It just so happened that XRR was involved with project Smokey, a 79 CJ turned in to a 79 CXYJ. The owner of the 79 CJ had acquired an 89 XJ and had robbed the head and other fuel injected related items for the AMC 258 that came with the 79 CJ. After all of the fuel injection items were removed the 89 XJ was bought as a sheet-metal donor for project Gumby. To keep the center of gravity as low as possible, the rear axle was moved back to the point where the front of the rear tire cleared the body just behind the rear doors at full compression. To accomplish the stretch, a main leaf from a Jeep Comanche was selected since its center pin is about 3” off-center (toward the rear) and it is also a slightly longer leaf spring as compared to the original Cherokee spring. In addition to using the Comanche main leafs, the custom spring pads for the rear Dana 60 were drilled about an inch off center.

Since we had a sheet-metal donor it was decided that most of the rear quarter would be removed and that the donor sheet-metal would be used to keep the original look of the Cherokee, giving the Cherokee a full body look instead of the comp look. By doing this we widened the wheel well approximately 6”. Original Cherokee, the gas cap is located just behind the driver rear wheel. When the wheel well was widened we lost use of the original gas filler location. This was resolved by using a Jeep TJ filler which was re-plumbed to utilize the original fuel tank which was also moved to the rear approximately 3” to allow clearance for the differential at full compression. The original shackles on the rear suspension were almost horizontal when used with the longer Comanche leaf springs. A custom shackle relocation bracket, designed by Extreme Roc Rigs was used to compensate for the longer leafs. The XJ shackle relocation bracket uses the OEM shackle bolt along with mounting holes found within the frame making it a complete bolt on part.. Gumby’s finished wheelbase is 106”, approximately 5” longer than stock.

The front suspension on Gumby is a one-off radius arm design using 2-1/2”OD ¼”wall DOM for the main link and 2”OD 1/8” wall DOM for the upper link. The radius arm is connected to the Jeep via a custom transfer case skid plate made from ¼” steel plate that sets flush with the bottom of the uni-body. The main link and bottom link utilize QA1 heim joints while the upper link uses Rubicon Express large rubber bushings.

Extreme Roc Rigs fitted both axles with 5.39 gears. The front gears ride on an ARB air locker while the rear axle was made to be a “Lincoln Locker”. Both differential covers were reinforced with ¼ steel to protect the ring gear from any close encounters of the granite kind. The front stub shafts were replaced with 35 spline units and connected to the stock 35 spline inner shaft via a Dana Spicer U-joint. Warn Premium locking hubs were used to keep the wheels locked to the ARB locker.

We moved the entire wheel opening back to accomodate the axle stretch.

Initial testing of the suspension was performed by using a forklift to simulate compression scenarios. Cycling the suspension allowed us to see if there was any thing binding and also allow us to properly fit the axles with the correct length shock. Adjustments were made between cycles to dial in the suspension.

During the 2008 Toy 4 Tots ride at Grayrock ORV the once mildly modified Cherokee was reunited with the off-road park and began its life as Gumby. Gumby performed flawlessly on its maiden run and has been on several rides which have provided many opportunities for fine tuning in real-world use. Since its maiden voyage Gumby has been fitted with 1-1/2” wheel spacers on the rear as well as a rear disc brake conversion. Currently an exo-cage is being designed to protect Gumby and strengthen the uni-body Jeep.