Ultimate Adventure is our annual event when a group of selected readers, sponsors, and staff cover roughly a thousand miles on a fun summer road trip and 4-wheeling journey. Every year we build a vehicle as the official UA project vehicle. This year we’re building a hot rod trail Jeep to take on our weeklong off-road adventure.
Back in the 1940s the military wanted a vehicle similar to the flatfender MB Jeep that it was using, but a little bigger. Willys built two prototypes. They were known as the MLW2, for Military Long Wheelbase version 2. The Ultimate Summer Camp Jeep is what we call the third prototype, MLW3B, for Militaryish Longer Wheelbase version 3B. This is our official buildup vehicle for Ultimate Adventure 2015, and it is growing fast.
In the past we have built new vehicles and old vehicles for the UA, but this is an all-new old vehicle. It is starting as a newer Jeep frame and a built-from-scratch Aqualu aluminum Jeep tub. The tub was built starting with a CJ-3B–style body but then stretched almost 2 feet and given a larger door opening, and a longer tub with a wider bed to fit a fullsize spare. To motivate the little Jeep, we stole parts from other project vehicles we have had in the stable and stuffed them all together to make a pretty wacky machine. The entire project was put together at Synergy Manufacturing, the official fabricator of the 2015 Ultimate Adventure.
Step By Step
We like to recycle, and so we decided to reuse these parts from other project vehicles. The engine is the Chevy Performance LSA supercharged 6.2L V-8 we had in the Alabama Army Truck. That truck was getting a transmission swap, but when we hit a few speed bumps we decided to rethink the project and the little Jeep seemed like a better home for the 550 hp. The two Spidertrax axles in the background are from our double-ended Jeep JK (Ultimate Orange Jeep) we built for the 2012 Ultimate Adventure. That Jeep got a set of Dana axles recently, so we decided that these lightweight Spider-9s would be just right under the new project.
We didn’t want to add rear steer to this Jeep (at least not yet), so we opted to reuse the front Spidertrax axle and build a straight 9-inch for the rear. The rear axle uses the same ultimate unit bearing as the front, so we will reuse those parts and the brakes off the rear-steer axle. We’ll have more axle buildup coverage in the future.
The Synergy team designed a set of motor mounts for the LSA out of TIG-welded chromoly plate that will attach to the JK frame and arc up high to clear the upper suspension link at full compression. The engine is centered in the frame and leans back approximately 5 degrees.
On the bottom of the LSA we added a Tilden Motorsports oil pan.
These steel fabricated pans offer high-clearance front axle movement, and a baffled sump to more constantly feed the oil pump during off-road use.
Behind the big power of the LSA we are putting in a built 4L80 transmission from Gearstar. These transmissions are built for the power and abuse we plan on dishing out and come shipped to your door ready to bolt in. We’ll be running the transmission fluid through a Ron Davis heat exchanger to keep it cool and using a Chevy Performance transmission controller to make it run and drive.
The transmission will feed power down to our Spidertrax axles, where we have a set of GearWorks high-pinion 10-inch differentials. The front differential has a GearWorks locker, and the rear is a spool. This should give the Jeep tough, reliable, no frills traction with a massive gearset.
About this time our Aqualu tub arrived in a giant crate. The bodies are made in Canada and can be shipped to your door if you’re ready to replace that rusty Jeep or Toyota body on your own project.
If you have 550 hp and a strong transmission, you need a beefy transfer case to send that power to both axles. The guys at Offroad Design recommended their Magnum 205 gearbox and doubler. We’re using a Ford transfer case with the driver-side front output. The doubler gives us four transfer case gear ratio options: 1:1, 2:1, 2.72:1, and 5.33:1. Multiply that by our axle’s 5.40:1 ratio and 2.48:1 First gear in the transmission, and we have a whopping 71.37 crawl ratio. That should be good.
With the Magnum 205 and 4L80, our little Jeep isn’t so little anymore. The long drivetrain offers us multiple low and overdrive gear ratios, but it also requires a longer wheelbase. Luckily we had the tub built to accept a 107- to 109-inch wheelbase. With that much power, having a little longer, more stable footprint won’t be a bad idea.
Even though we were a long way from bolting on the Aqualu hood and Omix ADA replacement grille, it sometimes helps a build to get an idea of where you’re headed. We realized early that we should have added another 3 or 4 inches of hood length to clear the air intake and radiator/intercooler in front of the supercharged V-8, but we will make it work for now.
After the engine is mocked up it is time to start the suspension. Since we are using a JK frame, you would think we would use an off-the-shelf suspension kit, but we opted to design a custom three-link front suspension with a track bar using BDS Suspension’s builder parts and Fox racing shocks. This will give us a suspension designed around our drivetrain and allow us to fine-tune it to get all the power to the ground and soak up bumps at high speeds.
One of the secret parts of our front suspension is a right-hand-drive Jeep JK steering box. These usually mount on the inside of the passenger-side frame, but we moved it to the outside of the driver side to gain room for our radiator to cool the big engine. (See how everything is connected?) We ordered up two steering boxes from RockAuto.com so we have a spare because we don’t expect to find a spare very easily, and had them ported for ram assist at PSC Motorsports.
By moving the box to the outside of the frame we were able to run a longer draglink and a longer track bar. This gave us less side-to-side movement as the suspension cycles. The front Spidertrax axle is a fabricated housing so it’s easier to add an upper suspension link to the top of the differential than it would be with a common cast iron axle. In Part 3 we will show you how the Jeep turned out, but we’ll be updating the buildup for quite a few more months.
Clackamas, OR 97015