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This Leaf Sprung JK Is Anything but Ordinary

Posted in Features on July 4, 2016
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Jake Hallenbeck has built his fair share of buggies, Jeeps, and trucks over the years. While many of these have run coilover shocks and link suspensions, he took a different direction with his 2008 JK Unlimited.

“Some of these aftermarket suspensions cost upwards of $10,000,” Jake says. “I have less than that in all of the modifications I have performed on my Jeep.”

Of course, Jake also has a ton of sweat equity in his Jeep, but the modest cash outlay is still impressive considering how extensive the modifications are. They include 1-ton axles, 40-inch tires on beadlocks, and leaf springs. Say what? That’s right. Jake grafted leaf springs on his JK and has been very pleased with the results.

“The handling on the road is great and they flex like mad on the trail,” he reports.

Judging by where we saw Jake take his Wrangler it’s hard to argue.

The stock 3.8L engine still resides under the hood of Jake Hallenbeck’s JK, with 99,000 miles on it. While these engines do not have a stellar reputation, Jake reports that the manual transmission and low axle gears help keep the engine in its powerband.

A Banks RamAir intake helps free up extra horsepower and is complemented by a custom 2 1/2-inch exhaust with a Dynomax turbo muffler at the other end. The torque peak on the V-6 is 1,000 rpm higher than a 4.0L engine (4,000 versus 3,000 rpm) so freeing up the airflow in and out of the engine is critical.

See something missing here? Jake completely defeated the ABS and traction control systems on his JK when he added the Super Duty axles. He used a wheel sensor from a Ram truck on the Ford front axle and reported that it bolted right on to the axle and into the Jeep connector. This took a lot of trial and error but has worked well for Jake.

The front suspension uses Wagoneer rear leaf springs on custom hangers with 14-inch-travel King 2-inch remote-reservoir shocks on Ford Super Duty shock towers. This setup allows fitment for the 40-inch tires with ample wheel travel.

PhotosView Slideshow

Jake added custom spring hangers directly on to the front bumper. He was able to move the front axle forward 2 inches to clear the fenders since the JK uses a pitman arm that faces forward. The factory crash bar was removed in front for increased approach angle with the use of the diminutive bumper.

The steering links were constructed from 1.5x0.250-wall DOM tubing fitted with GM 1-ton tie-rod ends. In order to mount the draglink above the leaf springs, a passenger-side knuckle from Reid Racing and a steering arm from XXX Traction were used.

Jake used a 2010 Super Duty front axle since they have larger knuckles, brakes, and U-joints than earlier Super Duty axles. The axle came with 35-spline axleshafts from the factory but has been upgraded with 5.38 gears and an Eaton ELocker behind the Solid diff cover. The most difficult part was cutting off the suspension brackets and fitting a spring pad on the cast section of the on the driver-side differential.

The side-mounted fuel tank of the JK made it easy for Jake to stretch the wheelbase to 123 inches. The rear suspension uses a simple leaf-spring suspension with the same 47-inch-long springs and 14-inch-travel King shocks as the front. A custom traction bar was built from 1.5x0.250-wall tubing. Jake said that the traction bar only limited wheel travel by half an inch and does an excellent job of preventing axlewrap.

The rear axle is also out of a 2010 Super Duty with an 8x170 bolt pattern. The Sterling axle has a 10 1/2-inch ring gear and disc brakes from the factory, so all Jake had to add under the Solid diff cover was the 5.38 gears and more clutch packs to the factory limited slip to tighten it up.

Rolling stock consists of 40-inch Nitto Trail Grapplers mounted on Teflon-coated ATX Chamber Pro beadlocks. Note how the Chamber Pro uses a 3/4-inch-thick beadlock ring with countersunk socket head cap screws to protect the hardware in the rocks.

PhotosView Slideshow

The interior is basically stock, with the addition of a custom rollcage constructed from 1.75x0.120-wall DOM tubing. Hallenbeck routed the rollcage through the dash for a clean installation with no loss of legroom, but he did have to cut and section the vents and speaker housings in order to retain their functionality.

Extraction duties are handled by a Bulldog 9.3k Alpha winch mounted on the stubby front bumper. These winches use series-wound motors with 500-amp sealed contactor switches.

Most aftermarket fenders are wider than stock for added tire coverage, but they don’t do anything to help off-road visibility. Jake modified the factory fenders to narrow them by 6 inches and then added mounting tabs to reattach them to the sheetmetal.

Lighting comes from a Snevey’s Off-Road Black Widow 50-inch hybrid LED light bar on custom low-profile mounts. As if that weren’t enough, a pair of Highlander LED light pods from Snevey Off-Road add 1,440 lumens.

This Jeep actually started as a 2WD. If you are going to toss out the factory axles and suspension anyway, why not save the money up front? Jake built a custom skidplate on the back of the factory crossmember to protection the NP241 Rocktrac transfer case. Heavy-wall CV drivelines from Driveline Service of Reno were built with 0.188-wall tubing and 1350 U-joints.

PhotosView Slideshow

Tech Specs
2008 Jeep Wrangler Unlimited
Drivetrain
Engine: 3.8L V-6
Transmission: NSG370 6-speed manual
Transfer Case: NP241 Rocktrac
Front Axle: Dana 60 with 5.38 gears and Eaton ELocker
Rear Axle: Sterling 10.5 with 5.38 gears and factory limited-slip differential
Suspension
Springs & Such: Wagoneer rear leaf springs and King shocks (front and rear)
Tires & Wheels: 40x13.50R17 Nitto Trail Grapplers on 17x9 ATX Chamber Pro beadlock wheels
Steering: Custom 1.5x0.250-wall DOM tie rod and draglink with 1-ton Chevy tie-rod ends, Reid Racing steering knuckle and XXX Traction steering arm
Lighting: Snevey’s Off-Road 50-inch LED light bar and LED light pods
Other Stuff: Banks RamAir intake, Bulldog winch, custom fender flares, custom rollcage, owner-built bumpers, custom rock sliders, custom 3/16-inch corner guards

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