The Hot Dog had to get finished. We were in the process of moving into a new (old) home. It was only 10 miles away from our current living quarters, but we didn't have a trailer large enough to haul the huge J-truck (it's 102 inches wide). So a few days after rolling it out of the garage, the Hot Dog went on its maiden voyage in the middle of the night on back roads to avoid any police interruption (it isn't exactly what we would call street legal). We got it up to around 35-45 mph, but who knows how accurate the speedometer is anymore.
Simply applying the pinion brakes stopped the Jeep easily but caused both axles to wrap more than we liked. Gassing it hard had similar effects. Steering the 49s felt almost like turning the stock 30s when moving, but at a stand still, it was difficult to turn (See the story "Easy Assist" for the solution to this problem). And, of course, the 49-inch Interco Irok tires were practically square from being cold and sitting in the same place for more than a day. Here's what we did to finish it and what we've changed since the short drive and a little bit of wheelin'.
How it Works Off-Road
Having the biggest tires and Jeep doesn't necessarily make it more capable than smaller, more nimble Jeeps. It's just different. What may be an impassable obstacle for a small Jeep can get gobbled up under giant 49-inch tires. But a simple flat, narrow and twisty trail can stop a big Jeep in its tracks. After spending some time in the driver seat of Hot Dog, we have a good idea of what it can and can't do. With its 126-inch wheelbase, it's good at climbing vertical ledges up to about six feet tall. At 102 inches wide it doesn't fit well in tight notches, but it's extremely stable on side hills.
For us, the best tire pressure in the 49/21.50-17 Interco Super Swamper Iroks is 3 psi in the front and 2 psi in the rear. Of course without the Trailready bead locks, we would have certainly popped a bead or two running pressures that low. The Irok sidewalls wrinkle over obstacles and under torque but don't cause the bounce normally associated with some big tires. It's possible we got lucky with the suspension design. Regardless, with our suspension and the huge tires at pressures in the single digits, you don't feel bumps smaller than a grapefruit and the traction-grabbing tire footprint is larger than your back.
Speaking of suspension, it flexes much better than we thought it would. We located the bumpstops nearly perfectly. At full stuff the tires rub slightly. We need to trim the fenders just a little more than we already have. However, we did run into some problems with the rear traction bar. The bushings on the axle end spit themselves out because of too much tweaking. Installation of some Rubicon Express Super-Flex joints at the axle end will probably be in the future.
A little lower gearing in First would be nice with the carbureted 304 V-8. The crawl ratio of the J-truck is about 85.0:1. Something around 100.0:1 would be perfect. If it had fuel injection the 85.0:1 would be fine. We couldn't ask for better steering. The West Texas Off-Road ram assist added to the stock pump and steering box worked out extremely well. It's a tad slow and heavy feeling at speeds but never difficult to steer when crawling.
Probably the most asked about components on the J-truck (not including the tires) are the USA 6x6 pinion brakes. Because they are geared 6.72 times through the Rockwell 2 1/2-ton axle gears they will stop the Jeep on a dime. Our stock power-assist drum brake master cylinder rounds out the brake system. Some systems using pinion brakes will require the installation of adjustable proportioning valves front and rear. For us, it's easy to stop slowly, and they still work well even when the engine stalls.
The short drive revealed that...
The short drive revealed that we needed more fender trimming than cutting the factory steel flares off. In the rear we cut small sections out of the fender area, used a small hydraulic jack to push the inner wheelwells open, and then welded it back together for a wider opening that kept the wheelwells intact and the bed rigid.
We ordered a bomb-proof rear...
We ordered a bomb-proof rear driveshaft from High-Angle Driveline. The company used three-inch 0.120-wall tubing with a 1410 Rockwell flange on one side and a 1350 U-joint on the other. We didn't need a CV, it was almost a straight shot to the transfer case. The rear axle and driveshaft just clear the stock gas tank. Orme Brothers built us a nylon-sleeved stainless braided brake line to attach the factory stopper system to the USA 6x6 pinion brake. After the short road trip, we built a simple traction bar to control axlewrap. The axle end features two urethane spring bushings.
The frame end of the rear...
The frame end of the rear traction bar features large Rubicon Express Super-Flex joints (PN RE3792). They're the same rebuildable joints the company uses on its suspension kits. They allow 32 degrees of misalignment, making them perfect for link-type suspensions and our traction-bar setup that sees some side-to-side movement as well as forward and back.
You'll need to assemble the...
You'll need to assemble the Super-Flex cartridges when mocking up your traction bar. Be sure to disassemble the joints before fully welding the assembly. Tack welding is fine but too much heat will damage the races. The Rubicon Express cartridge rebuild tool (PN RE3772) and large snap-ring pliers make assembly and disassembly easy. Watch out for weld boogers in the threads of the joint when you're done welding.
Up front we built a torque...
Up front we built a torque arm with Super-Flex joints to control axlewrap. This type of traction-control device is not 100 percent effective like out rear setup. However, it doesn't adversely affect the suspension movement. We also had the ears machined off the front pinion yoke to keep them from snagging the drag link at full stuff.
Another High-Angle Driveline...
Another High-Angle Driveline shaft feeds the front axle. We opted for the booted super-long-spline unit to work with our shackle reversal. We plugged the driver-side front brake line and ran our new stainless Orme Brothers hose from the factory passenger-side hard line to the USA 6x6 pinion brake.
We cut off the factory front flares, trimmed the front bumper and removed some of the inner fenderwells behind the turn signals. The tires just kiss the rear parts of the fenders at full stuff while turning. The Hot Dog doesn't have a lot of up travel, but it sits low and stable.