Outfitting a Jeep Wrangler for towing and off-road fun.
By Mark Quasius, F333630
Walk around most RV parks and you likely will notice a number of Jeep Wranglers set up for four-wheels-down towing. Wranglers are available in two versions: a short-wheelbase, two-door model and a longer four-door Wrangler Unlimited.
The four-door Unlimited is extremely popular with the RV crowd. It’s easy to tow and offers a comfortable ride, respectable performance, lots of room, and the ability to explore places that are inaccessible with a typical towed vehicle. It’s a great choice as both a daily mode of transportation and a fun toy for the weekends. For the motorhome owner, the Jeep is the perfect blend of practicality and fun. What’s more, an aftermarket culture has created a multitude of accessories for Jeep owners who take pride in their vehicles. If you are one of those who wants to do serious off-road travel, it is possible to modify your Jeep for the rigors of off-road fun while continuing to use it as a towed vehicle.
With that premise in mind, I decided to set up my 2012 Jeep Wrangler Rubicon Unlimited for double duty. This Jeep is capable of tackling most off-road terrain but also is easy to tow. I didn’t buy monster tires and install huge lift kits, yet the vehicle has the ability to traverse terrain that would send many SUVs to the scrap heap.
Jeep Wranglers come in three basic styles: Sport, Sahara, and Rubicon. Each is easy to tow behind a motorhome, and there are no speed and distance limitations. Simply hook up to the tow bar; connect the lights, safety cables, and auxiliary braking system; and slip the transfer case into neutral. The Rubicon is Jeep’s top-end Wrangler and includes features such as electric sway bar disconnects; larger Dana 44 axles with electrically locking differentials; the heavy-duty Rock-Trac transfer case with 4:1 low range; more aggressive tires; and other features that are beneficial to off-road travel. However, any Wrangler is ready and more than willing to go exploring off-road.
A few changes have been made to the JK series Wrangler since it was introduced back in 2007. At some point during the 2008 model run, the steering wheel ignition lock was removed. This meant that you no longer had to insert a dummy key into the ignition to unlock the steering wheel when towing, which was a welcome improvement for those who tow Wranglers. In 2011, in honor of Jeep’s 60th anniversary, the Wrangler received some attractive interior upgrades and new amenities such as power windows, power door locks, keyless entry, remote start, and a disc-based entertainment system with GPS. The 2012 models saw the advent of a new power-train system. The 3.6-liter dual overhead-cam Pentastar engine brought an additional 80 horsepower, and a Mercedes-Benz-built five-speed automatic transmission greatly improved drivability.
Base Plates And Off-Road Considerations
If you don’t plan to use the vehicle for off-road adventures, other than to take it through muddy fields, setting up the vehicle to be towed is simple. Just choose your favorite tow bar; buy and install a base plate that is designed for the vehicle; wire up your towing lights; add an auxiliary braking system; and you’re all set.
If you do want to use it for off-road adventures, the setup can become a bit more complicated. Tow bar base plates mount to the Jeep’s frame and extend below the front bumper. This puts the towing equipment in harm’s way should the Jeep get hung up on a rock or bottom out in deep ruts. If the base plate becomes bent, it may be impossible to hook up the tow bar and tow the vehicle. The chances of this happening limits where the Jeep can be driven. Adding skid plates will protect the Jeep’s undercarriage, but it won’t protect the base plate. Adding lift kits will provide more ground clearance, but, again, the base plate is still mounted low to the frame, because a lift kit raises only the body. Installing larger tires may add some clearance, but if too much height is added, you may run into a tire wear issue when towing. The best option I found was to install a bumper that’s strong enough to handle a set of tow bar mounting brackets connected directly to it. That way the area beneath the front bumper is clear for better approach angles, and damage to the towing setup can be avoided.
After doing a fair amount of research, I decided to use Rock Hard 4×4 products (308-750-4690; www.rockhard4x4.com). Rock Hard initially impressed me with a great-looking design. After further inspection, I saw that the company has a commitment to quality and strength. Rock Hard bumpers are made of 1/4-inch plate steel rather than 3/16-inch steel. The company also offers custom tow bar brackets that fit Blue Ox and Roadmaster tow bars. The full-width front bumper was formed so that it also covered and protected the factory lower cross frame and sway-bar-disconnect assembly. This bumper also came with locations for the factory fog lights, which could be reused. Tow shackle mounting locations incorporated into the bumper double as safety cable connection points when towing. The bumper also included a number of places where I could neatly install the towed vehicle lighting socket, the breakaway switch, and a connection for the auxiliary braking system.
A low-mount winch location was provided to allow maximum airflow to the radiator, and it was large enough to handle the Warn PowerPlant winch I chose (800-543-9276; www.warn.com). The PowerPlant winch features an onboard air compressor as well as a winch. This makes it possible for me to partially deflate the tires for maximum grip when driving off-road and then reinflate them for the drive back to the RV park.
For additional undercarriage protection, I ordered a complete set of skid plates from Rock Hard as well as a set of Mopar tubular rock rails from my local Jeep dealer. The 2012 Wrangler has a vacuum booster pump mounted near the front bumper. This pump wasn’t required in previous years, and it gets in the way of many aftermarket front bumpers, which were designed to fit 2007 through 2011 Jeeps. Rock Hard supplied a relocation bracket for this pump to move it out of the way.
To connect the Jeep’s rear lights to the RV, I installed a Tow Daddy Plug-n-Tow module (888-986-9323; www.towdaddy.com). The Tow Daddy module offers a simple and safe way to tie your existing lights into the motorhome’s lighting feeds when towing.
Finally, an M&G Engineering (800-817-7698; www.m-gengineering.com) auxiliary braking system was selected. This system utilizes the motorhome’s air brakes to operate the towed vehicle’s brakes with proportional braking. The module is fully contained under the Jeep’s hood and does not tap into the Jeep’s electrical or hydraulic braking systems. Once installed, the system is failsafe and foolproof.
Installing The Rear Bumper
I began the project by removing the original rear bumper and setting it aside. The original bumper is made of hollow plastic, so it’s easy to lift. Handling the new bumper wasn’t as simple, since it was fabricated with 1/4-inch steel plate. Consequently, I used a floor jack to lift the new bumper into position. Once I had it aligned, the bumper slid into place and was bolted tight. The original bumper had a molded recess where the spare tire hung. I found that the spare tire hit the hitch receiver on the new bumper. Thankfully, Rock Hard supplied a new tire mount bracket that raised the spare tire high enough to clear the bumper. When I later replaced the original 32-inch tires with a set of 33-inch Goodyear Wrangler DuraTrac tires, everything fit just fine. However, if you plan to use 35-inch or larger tires, I’d recommend getting Rock Hard’s rear bumper with a swing-out tire carrier instead.
The rear bumper also includes locations for a pair of 3/4-inch retrieval shackles. If you ever need to be pulled out of a mud pit or other sticky location, these will prove handy. Even if you never have to use them, they look cool. The Wrangler has a towing capacity of 3,500 pounds, so towing smaller trailers is certainly within its capabilities.
The front bumper was the heart of my upgrade project, since it would be the connection point for the tow bar once completed. I began by disconnecting the fog lights and removing the original plastic front bumper. The fog lights were easily transferred over to the new bumper, but the wires were a bit short, so I spliced some extensions into the OEM harness to allow them to reach. Next, the vacuum booster pump was removed and the original mounting bracket was cut off so that it wouldn’t protrude from the frame rail and get in the way of the new bumper. The relocation bracket supplied by Rock Hard was mounted and the pump attached to the new bracket.
Mounting the bumper and winch can be done in one of two ways. You can mount the winch to the bumper and install the combination as one piece; this makes it easier to get to the mounting bolts but also makes the entire assembly heavier to lift onto the Jeep. You also can install the two parts separately. Since I was doing this installation by myself, I decided to mount the bumper first and then add the winch. I lifted the bumper into place without jacks, because it was easy enough to slip it onto the frame rail extensions. But I must warn you: it was a serious lift, and I recommend that this be done by two people, if possible. The bumper has a large opening to accommodate the Warn PowerPlant winch, but it fills the entire area with not much room along the side. I found that the OEM bumper mounting brackets intruded slightly into that area and wouldn’t allow the winch to fit, so I marked the protrusions; took off the bumper; and used a small disc grinder to remove a portion of the bracket. I reinstalled the bumper and the winch fit just fine. Eight bolts mount the bumper to the ends of the frame rails — four on each rail. Two of them can be used to attach the tow bar mounting brackets. You can use the bottom pair or the top pair, depending on how high you want the brackets to be. I chose the bottom pair. When attached in this manner, the tow bar brackets pull directly on the ends of the frame rails rather than the bumper itself, offering the greatest possible strength.
Next, a few holes were drilled to install the socket for the tow lighting cable as well as a connection for the M&G auxiliary brake air line from the motorhome. A breakaway switch was installed to activate the brakes should the Jeep become disconnected from the motorhome when towing. Finally, the D-ring shackles were installed on the front, and a snap-on license plate bracket was hung on the winch roller fairlead to make it legal. The bumper had a set of light-mounting tabs on its protective winch hoop, and I just couldn’t bear to leave them unused, so I added a set of KC Hilites (www.kchilites.com) 5-inch driving lights to dress up the bumper and provide additional illumination when needed.
Skid Plates And Rock Rails
I picked up a complete set of skid plates from Rock Hard. The heavy-duty plates protect the engine and transmission, the transfer case, and the fuel tank. A skid plate also was provided to protect the fuel system’s evaporation canister, which was unprotected and prone to damage, although Jeep began including a stamped steel plate as of the 2012 model year. Finally, a muffler skid plate was added. The muffler on the Jeep is transversely mounted behind the rear bumper and is subject to damage should the back bumper bottom out when rock crawling or when exiting the base of a steep downgrade. Granted, it’s just a muffler, but this plate hides the muffler and protects it for better appearance. Once all of these skid plates were installed, the bottom of the Jeep looked more like a Tiger tank than an SUV, but everything was protected. The Mopar rock rails mounted under the driver and passenger doors provide rock and rub protection when maneuvering through tight areas.
An auxiliary braking system with a breakaway feature is a necessity on any vehicle towed behind a motorhome. I’ve had excellent success with the M&G auxiliary braking system, which utilizes the RV’s air brakes to control the towed vehicle’s brakes in the same proportion as the motorhome’s brakes. I stuck with what I thought to be the best and ordered another system from M&G.
To install the M&G system, one must remove the master cylinder from the vacuum booster so that the M&G module can be inserted between the two units. An air line connects the module to a quick-disconnect fitting at the front of the Jeep, which is then connected to the air brake line that runs from the motorhome’s air brake system. Whenever the motorhome brakes are applied, air pressure enters the M&G module and spreads two pistons apart to energize the master cylinder and apply the Jeep’s brakes. When no air is present, the pistons return and the entire module acts as a large pushrod for normal driving and is failsafe. An optional breakaway valve is connected to a small air tank so the brakes will be applied in the event of a breakaway, and an electric breakaway switch is mounted on the front bumper to energize the solenoid to apply the brakes in the event of a runaway.
Installing the M&G module into a Wrangler required a slight modification. The existing antilock braking system (ABS) module was in the way and didn’t allow enough clearance to move the master cylinder forward and insert the M&G module. Cutting away the plastic baffle per the M&G instruction sheet allowed the relocation of the ABS module to provide adequate clearance. The small air tank is attached to the firewall, and the breakaway solenoid mounts to the inner fender. I drilled a 1/4-inch hole into the top surface of the front bumper and attached the breakaway switch to it. Nylon air lines between the breakaway solenoid, air tank, and M&G module were then cut and installed.
Wiring It All Together
Once everything was bolted in place, it was time to wire it all up. The Tow Daddy Plug-n-Tow system is designed to plug right into the Jeep’s taillight harness without splicing. However, the harness is better designed for a car trunk, with the control module in the middle. I placed the module behind the left taillight, so the wires that run to the right side taillight weren’t long enough and needed to be extended. The wires that feed the system were then run up to the front bumper area, where they were connected to the lighting socket installed in the front bumper. The Tow Daddy system is inactive during normal driving, but it disconnects the OEM wiring when towing and feeds the lighting signals from the RV to the lights instead. Diagnostic LED lights indicate any potential problems.
I also ran a battery hot line from the motorhome to the Jeep to keep the towed vehicle’s battery charged when towing. A 20-amp circuit breaker was installed in the #12 wire at the motorhome end as well as at the Jeep to protect the wiring in the event of a short circuit. The Warn PowerPlant winch was then connected to the battery terminals.
With recent Jeeps that do not have a locking steering wheel, there is no need to keep a key in the ignition when towing. However, older Wranglers do require a key to unlock the steering wheel when towing. To eliminate drain on the battery, Tow Daddy offers an Auto Fuse device, which plugs into your towed vehicle’s fuse box and relocates the ignition column or ECM fuse. It also has an electronic relay that is connected to your tow light socket. Whenever you plug in your wiring harness, the relay automatically disconnects the power to the key switch. As soon as you disconnect the RV’s cord from the towed vehicle, it re-energizes the circuit for normal driving. It’s a great setup, particularly for those own an earlier model that requires a key to unlock the wheel.
Once everything was installed, we were done. Or were we? The weight of the heavy winch, front bumper, and all those skid plates caused the front of the Jeep to drop about 11/2 inches from the factory height. Wranglers typically have a 1-inch rake to them that is supposed to give the vehicle better aerodynamics; although I don’t think a big, square Jeep benefits much from that. A TeraFlex front coil spring spacer kit from Quadratec (800-745-2348; www.quadratec.com), which was designed to raise the Jeep 2 inches, was added to the front coil springs. This gave us back the 1 1/2 inches that we lost and raised it up an extra 1/2-inch to reduce the rake and make it appear more level.
My Blue Ox (888-425-5382; www.blueox.us) tow bar was disassembled, sandblasted, and painted with Eastwood 2K Aero-Spray Chassis Black gloss paint. All worn parts were replaced, and I even picked up a shiny new set of locking hitch pins to replace the pitted ones that I had been using for years. I figured that I would have to use an offset hitch adapter in order to get my tow bar level. It’s important that the receiver hitch of the motorhome never be more than 4 inches higher than the towed vehicle attachment points. Ideally, the tow bar should be as close to level as possible. Fortunately, using the lower mounting holes in the Jeep’s bumper, plus my spring spacer kit, made for a perfectly level tow bar and I didn’t need an offset adapter.
I attached the safety cables to the D-ring shackles on the front of the Rock Hard bumper, plugged in the air hose for the M&G braking system, attached the lighting cord, clipped the cable to the breakaway switch, and we were ready to hit the road. We never could tell the Rubicon was back there when towing, and it did not exhibit tire wear, death wobble, or any other problems. Just hook it up; shift the transfer case into neutral; and you’re ready to go.
The Jeep was well-mannered in city traffic and gave an excellent ride that one wouldn’t expect from an SUV designed for serious work. It was equally at home on Montana’s high-speed highways, and fuel economy was improved over previous Jeeps. When we got off pavement in Wyoming’s Bighorn Mountains, the Wrangler really proved itself. We could drive through rocky terrain without fear of damage, and the vehicle was just plain unstoppable. It is perfect for a motorhome owner who wants to blend off-road fun with practicality.