Ultimate Adventure 2007 Jeep JK Wrangler - 4Wheel & Off-Road Magazine

If you've been following along then you know we are building a brand-new four-door Jeep Wrangler JK for this year's Ultimate Adventure trip. Plus you would already know that Ultimate Adventure is our weeklong off-road trip we do every year with a group of readers, advertisers, and friends. What you probably don't know is the scope of the enormous project we have taken on this year in order to build the Ultimate Jeep Wrangler.

Hey, there are no tires under that Jeep. In fact, there's nothing under that Jeep!

Jeeps are easily the most prevalent off-road vehicles in the U.S., so the challenge of building one different enough from all the rest to lead our UA trip is pretty daunting. Luckily we found an awesome crew to help transform our bone-stock two-wheel-drive (yes, two-wheel-drive) '07 Wrangler Unlimited into a monster off-road machine. Our first stop was at Twisted Customs in Rapid City, South Dakota, where we had a six-point cage installed last month. Twisted Customs is one of the top shops in the nation when it comes to building rock-buggy chassis, so we're confident in the performance of the cage if we need it. After that we drove the Jeep to Missoula, Montana, where we enlisted the help of American Expedition Vehicles (AEV) for the majority of the buildup. AEV is to Jeeps what Saleen or Roush is to Mustangs and Lingenfelter or Callaway is to Corvette. The folks at AEV are some of the best in taking a showroom Wrangler and transforming it into a top-of-the-line luxury trail machine. Their specialty is swapping the late-model Dodge Hemis into Jeep TJs and JKs but they also sell bumpers, wheels, and a pickup-truck conversion kit to turn your Jeep TJ into a Jeep "Brute" pickup (you'll notice some parked in the background of the photos; they're really cool). In addition to its normal products, AEV has won a few design excellence awards from Chrysler for its amazing concept cars displayed at the annual SEMA industry trade show. As you can see, AEV is a perfect choice for our biggest Jeep build ever, but we must explain this from the start. What we asked them to do to our Jeep is above and beyond anything they offer to customers, so don't expect them to be offering a kit anytime soon to swap a Cummins diesel into a brand-new Jeep Wrangler. Yes, you read that right, we are putting a massive 5.9L Cummins diesel under the hood of our Ultimate Adventure Jeep, but doing so has opened up a can of worms like no other. In fact, we were lucky enough to come across the entire drivetrain and chassis of an '06 Dodge Mega Cab that was on its way to the crusher, so rather than dropping the Cummins into the 1/4-ton Jeep frame, we instead chopped and squeezed a shortened Dodge frame under the freshly channeled JK body. And here is the best part: As this is being written the Jeep is sitting in AEV's shop, in pieces, and there is less than a month until it makes its debut at the start of Ultimate Adventure. Situation normal; time to get back to work.

After we delivered the '07 JK to American Expedition Vehicles, we began measuring the giant Cummins 24-valve, common-rail, 5.9L diesel engine and of course found it to be much larger than the factory '07 Jeep 3.8L V-6. The Cummins weighs around 1,100 pounds and is nearly 3 feet tall, 3 feet long, and 3 feet wide, so the project of stuffing that engine into the Jeep frame was going to be an uphill battle. However, the Jeep frame is no weenie frame as in olden days. In fact, its fully boxed chassis is made of tubing 2 3/8 inches wide by 5 1/4 inches tall-bigger than some 1/2-ton trucks we've seen.
After we delivered the '07 JK to American Expedition Vehicles, we began measuring the gian
Luckily we were able to get our hands on a complete rolling chassis for an '06 Dodge Mega cab that was headed for the crusher, and when we started measuring and examining the differences between the Jeep and the Dodge frame, we realized that the truck chassis could be shortened fairly easily. It already has big axles under it and all the proper mounts for the Cummins engine. Not to mention that this frame was engineered from the start for the torque the Cummins will produce. In the end we removed a 4-foot section of the 2 3/8 x 7 1/2 framerail from the center.
Luckily we were able to get our hands on a complete rolling chassis for an '06 Dodge Mega
With the Dodge frame shortened down to the Jeep's 116-inch wheelbase, we could roll it under the Jeep body to determine where the engine would sit and what bodywork would need to be done. About now the AEV crew decided to move the engine back in the frame almost a foot. This helps keep a balanced weight front to rear, offers more space for a custom radiator, and keeps everything under the factory Jeep hood and behind the original grille. It also means new motor mounts and a proverbial butchering of the Jeep firewall.
With the Dodge frame shortened down to the Jeep's 116-inch wheelbase, we could roll it und

In fact a massive hole was cut in the firewall to make room for the engine, plus the entire heating and air conditioning system had to be removed, for good. Luckily Hobart is the official welder and plasma cutter of Ultimate Adventure so when the old shop plasma cutter started acting up, Hobart came through with one of its Airforce 625 plasma cutters to help in the removal of unwanted metal. The 625 can cut up to 1/2-inch steel so it should work great for everything on this job. About this time you're probably wondering why we were going through so much trouble, and actually so were we. But whenever we thought about how awesome a diesel-powered Jeep would be, not to mention one running a Cummins diesel from a 1-ton truck, we felt it was a good cause and a great project. Plus we knew you would all want to know if it could be done and we hate to disappoint.

Our next step was to rebuild the firewall around the engine with enough space for any movement of the Cummins on the engine bay side, while still having some semblance of foot room on the occupant side. This meant stuffing the engine in the frame and dropping the body down over it. As you can see, the engine is quickly entering the Jeep tub looking for a place to live.
Our next step was to rebuild the firewall around the engine with enough space for any move
As we continued to build out the firewall, we realized that the passenger's left foot and the hot exhaust from the turbo dump will be trying to occupy the same space. Even worse, on the driver side the throttle pedal and the Cummins starter were having domestic disputes about living in the same place.
As we continued to build out the firewall, we realized that the passenger's left foot and
We looked into different options for the starter and even borrowed an early '90s Cummins starter (bottom) from U.S. Diesel Parts in Missoula, Montana. We eventually determined that by rotating the '06 starter (top) around in its mounting hole we could get it out of the way for the throttle pedal. This did involve some custom welding to the Cummins engine adapter that the starter mounts to.
We looked into different options for the starter and even borrowed an early '90s Cummins s

With the location of the starter solved, the firewall under the pedals was finished with some additional notches to clear the fuel filter. And with the original dash substructure back in, most of the firewall sculpting is unnoticeable other than the new heated footrest on the passenger side.
With the location of the starter solved, the firewall under the pedals was finished with s
Since the rear of the newly shortened Dodge frame kicks up, we also needed to do some massaging to the rear of the Jeep tub. To start, the AEV crew took an old hot-rod trick known as channeling, where the floor of the car is moved up to allow the body to sit lower over the frame. AEV simply cut out sections of the tub where the frame kicked up into it, and re-boxed them in so the JK didn't look like it had a 6-inch body lift. These new floor pieces will be under the rear seats mostly and won't deter from footroom much at all.
Since the rear of the newly shortened Dodge frame kicks up, we also needed to do some mass
With the tub modifications finished, the entire underside was coated with Lizard Skin Ceramic Insulation. This single-stage coating sprays on easily with an air gun and then dries to a dull finish that will help seal the floor and act as a heatshield and noise barrier. The official definition is "an advanced, water-based composition of high-grade acrylic binders with air-filled insulating/reflective and sound-absorbing particles." We just hope it helps us hear each other in the cabin of the Jeep and keeps our passenger's boots from melting to the floor. It also covers all the fresh bodywork and gives the firewall and underbelly of the tub a uniform finish.
With the tub modifications finished, the entire underside was coated with Lizard Skin Cera

We had to move the factory transmission crossmember to a different location since the engine was moved backwards. Also note the 1/4-inch fish plates attached to the inside of the framerail crossing over where the framerails were cut and shortened. Once painted it will be hard to determine from the outside where exactly the frame was cut apart and rewelded. Look closely and you can see where the crossmember was notched for the transfer case to be clocked down.
We had to move the factory transmission crossmember to a different location since the engi
Body mounts were added to support the Jeep JK tub on the Dodge frame, and gussets were added to the rear spring hangers. If you didn't catch it already, not only will this Jeep have a Cummins diesel but it will also have leaf springs in the rear just like the original Mega Cab. We decided to go this route because it's a tried-and-true system that Dodge uses. Our suspension sponsor Superlift offers a similar leaf-spring rear, coil-spring front suspension for Jeep YJs known as the X2 kit, so we thought we'd see how it would work in our JK.
Body mounts were added to support the Jeep JK tub on the Dodge frame, and gussets were add
In the rear of the frame a small notch was needed to clear a major body rib in the Jeep tub, plus the rear-spring shackle mounts were lowered a bit to clear the tub and tailgate. Long sections of the front and rear frame are remaining until we get ready to install the Fab Fours bumpers. This will allow us material to work with when attaching the Jeep bumpers to the Dodge frame. It may sound incredibly simple, but unlike many of the previous projects that AEV does-where they simply move digital drawings of the different parts around on the computer till it all fits before cutting anything on the vehicle-this build meant every notch and weld in the body and frame involved multiple repetitions of putting the body on the frame, marking points that interfered, pulling the body off the frame, and then cutting and fixing both. It was an incredible amount of work, but truly the best way to make everything work together.
In the rear of the frame a small notch was needed to clear a major body rib in the Jeep tu

Ua 2007 Jeep Wrangler Jk Front Side View

That's all the room we have for this month, but check back in 30 days when we stuff the engine in our freshly painted frame, roll some cool Dodge axles under it, drop the body on the whole thing, finish up all the other major things like steering, cooling, driveshafts, and suspension, and try to get it all painted and ready to go on Ultimate Adventure 2007. Here's a hint: We're building this big Jeep to fit the biggest BFGoodrich tires ever made and taking the whole thing to the biggest state in the lower 48

SOURCES
American Expedition Vehicles www.aev-conversions.com	Jeep 800-925-5337 www.jeep.com
Lizard Skin 877-278-9468 www.lizardskin.com	Off Road Design www.offroaddesign.com
Twisted Customs	Optima Batteries 5757 N. Green Bay Ave. Milwaukee WI 53201 414-524-1200 www.optimabatteries
U.S. Diesel Parts www.usdieselparts.com	Poison Spyder Customs
BFGoodrich Tires 877-788-8899 www.bfgoodrichtires.com	PSC Motorsports www.pscmotorsports.com
Fab Fours www.fabfours.com	Slee Off Road
Flowmaster Mufflers Santa Rosa CA 8-00/-544-4761 flowmastermufflers.com	Superlift Suspension
Hobart Welders N/A www.hobartwelders.com	Warn 5-03/-722-1200 www.warn.com