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Top 13 First Modifications We Would Make to the All-New 2018 Jeep JL Wrangler

Posted in How To: Body Chassis on February 21, 2018
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Photographers: Courtesy of JeepCourtesy Of Mopar

Whenever a new Jeep Wrangler is introduced, enthusiasts and the aftermarket rush to be the first to make modifications, and the all-new ’18 Jeep Wrangler JL is no different. The challenge is identifying what should be improved upon and what can be left alone. The modifications needed for the outgoing Wrangler model may not necessarily be what’s needed on the new Wrangler. For example, the new JL Rubicon is said to fit 35-inch tires stock, it has a massive 1.58-inch–diameter tie rod and draglink, and is available with an optional off-road¬–worthy steel front bumper. Because of the bigger wheel openings, lift kit sizes for the JL will surely need to be different than what’s available for the JK. It seems as though many of the things on the JK that had to be addressed by the aftermarket have been addressed from the factory with the JL. With all this in mind, we decided to spend a week in the new Wrangler JL and look at it with fresh eyes to come up with the top 13 modifications we would make first. We spent our on- and off-road wheel time in a Wrangler Unlimited Rubicon model, which will likely be one of the more popular trim levels for dirt-driving enthusiasts. However, many of the modifications we have listed here will work on the other JL trim levels as well.


Rocker Guards
Pretty much every 4x4 that hits the dirt should have some type of rocker area protection. How robust this body protection needs to be will depend on how you plan to use the vehicle, and the same is true with the new JL Wrangler. The factory Rubicon rocker guards are fine for general off-road use and protection against parking lot door dings and ghost-riding shopping carts. They attach at the body, so they really are not designed to support the weight of the entire Jeep when regularly sliding over boulders and rock ledges. If aggressive off-roading is in your plans, you’ll want to add rocker guards that incorporate the body mounts or attach directly to the frame. This will better protect the aluminum doors and steel rocker area of the JL.


No Lift Tire Size
The factory JL Rubicon tires are 285/70R17, which measure out to around a 33-inch tire. With no lift, the manufacturer says that 35s will fit for street use, but with the suspension fully articulated off-road there will be some tire rub on the inner wheelwells both front and rear. We think you could get away with bumping up the tire diameter one to two sizes to a 305/70R17 or 305/75R17 on the stock wheels with only minor inner fender contact at full suspension articulation. Of course, if you are willing to remove the plastic inner wheelwells and lower the bumpstops or live with significant tire rub off-road, you could surely fit a 35x12.50 or 315/70R17 on the stock Rubicon wheels.


Fitting 35x12.50 or 37x12.50 Tires
With the generous wheel openings, it seems natural that the Rubicon model should have 35-inch tires. In order to cleanly fit 35x12.50 or 315/70R17 tires both on- and off-road, a 2-inch lift kit could be implemented. However, this seems to leave the wheel openings looking empty. We think a 1-inch lift or 1-inch bumpstop extensions could be used to keep the tires out of the wheelwells. You might be able to retain the factory Rubicon wheels, but you’ll likely want wheels with around 1-inch less backspacing. Fitting 37-inch tires will require a 2-inch lift, bumpstop extensions, wheels with less backspacing or wheel spacers, and probably some inner fender trimming.


Rubicon Flare Swap
The factory high-line fender flares are part of the reason the 285/70R17 tires fit on the Rubicon. These factory flares increase the size of the wheel opening and could be bolted onto the non-Rubicon models to provide more tire clearance.


Cut to Fit Flares
There will surely be those that want to step into taller and wider tire and wheel packages without modifying the suspension. This looks like it could be done without much cutting. The fender flares are made from two pieces. You should be able to remove the plastic rivets and take off the lower portion of the flares along with the marker lights on the front flares. This would provide an additional 2-inches of outer fender flare clearance. Of course, you’ll still have to either trim or remove the inner fender liners because they will no longer have any support along the outer edge.


If no tire size increase is planned, we’d have a really hard time messing with the JL suspension given the smooth ride and great performance on- and off-road. However, one area that could use some improvement in the dirt is the shocks. If you like wheeling around the desert at speed, you’ll quickly overheat the factory shocks. We’d like to see some bolt-on, lightly-valved, position-sensitive shocks be made available for the JL. It shouldn’t be too tough; there is plenty of room and all four shocks now feature heavy-duty eye mounting at both ends. We’re thinking larger-diameter adjustable external or internal bypass shocks would be a great addition to an otherwise stock JL suspension system.


The factory stamped steel skidplates will provide ample protection in most off-road scenarios; however, regular rock contact will take its toll on the light-duty OE fuel tank and transfer case skidplates. If you foresee granite in the future of your JL’s underside, the main structure of the original transfer case/transmission skidplate will benefit from a heavy-duty replacement. Real bashers will want a skidplate that extends forward to protect the automatic transmission lines, exhaust crossover, and engine oil pan. We’d love to see someone make use of UHMW material on the skidplates to help the JL slide more easily over obstacles. Also, even though the suspension control arm brackets on the front axle are tucked up relatively well, they would benefit from some weld-on skidplate gussets.


The JL front and rear driveshaft architecture is very similar to the driveshafts found under the JK. The rear driveshaft features CVs on both ends and the front driveshaft has a CV on the transfer case end and a U-joint on the axle end. In most circumstances, the CV joint is actually a better design than a U-joint. However, the CV-style driveshafts are far less tolerant of joint bind and being dragged over boulders. Taller lifts, increased wheel travel, and rocky wheeling will generally be best accomplished with front and rear aftermarket driveshafts with U-joints at both ends. The good news is that you no longer need to modify the exhaust for driveshaft clearance when lifting the Wrangler. The factory JL exhaust should clear the front driveshaft fine with several inches of lift.


Axle Gearing
The new ZF 8HP eight-speed automatic transmission in the JL really makes great use of the power available from the 3.6L V-6, so much so that we think the Rubicon 4.10:1 ratio axle gears should be good for up to 35-inch tires. Bumping up to 37-inch tires will likely require 4.88:1 or 5.13:1 ratio axle gears, which are not yet available. The jury is still out on what axle gears would be needed for the optional 2.0L four-cylinder gas turbo engine and 3.0L diesel.


Speedometer Correction
As with all modern 4x4s, the engine and automatic transmission performance is extremely dependent on vehicle speed input. Altering the tire diameter and axle gear ratio will cause the input speed to be incorrect, which can lead to much more than a false speedometer reading. Results include incorrect transmission shift points, poor shifts, and even transmission overheating and failure. The cure is simple. Correct the speedometer so the engine and transmission computers receive accurate speed info. This can be done several ways, but it’s typically done with an aftermarket controller that plugs into the OBDII port. As of this writing, there aren’t any products available to make the correction on the JL, but we are sure they will be available soon.


Axle Upgrades
The all-new Dana 44 axles found in the front and rear of the JL Rubicon are said to have been engineered with up to 35-inch tires in mind. The massive 2.75-inch front and 3.12-inch rear axletubes will certainly provide more beef underneath. One area of discontent for many Jeep enthusiasts is with the JL center axle disconnect (CAD) system, and rightly so. The YJ CAD system left a bad taste in the mouth of Jeepers as far back as 30 years ago. However, the problematic YJ system was vacuum operated. The JL uses an electric solenoid, similar to the front axle disconnect found in current-model Ram 2500 and 3500 trucks as well as many other modern 4x4s. The real advantage most people forget is that the JL front driveshaft and ring-and-pinion will not be spinning when the transfer case is shifted into two-wheel drive. This will reduce drivetrain wear and vibration and increase fuel economy. Also, spinning bent and unbalanced front driveshafts in the outgoing JK have been known to cause the transfer case to split in half on the highway. Regardless of if the JL front axle disconnect is a problem, we’re sure the aftermarket will offer CAD delete axlehousings, axleshafts, and other products to keep everyone happy. Although, we would probably save our money for a while to see if the JL CAD system actually becomes problematic.


Onboard Air
The one thing we really hoped the new JL Rubicon would come with was a factory air compressor that could be used to inflate tires, air mattresses, and recreational floats. Fortunately, the aftermarket is flush with many different air compressors. Unfortunately, there isn’t a lot of space under the JL hood for accessories. Even a dual battery kit will be a tight fit. We’d like to see someone make use of the removable plastic tray in the rear trunk area. The tray could be easily replaced with a steel or aluminum block-off plate that houses an electric air compressor and a small tank, which could be tapped into from the rear of the Jeep with a chucked air hose.


Additional Lighting
The optional LED lighting group includes LED headlights which are significantly more useful at night than some of the headlights used on past Jeep models. This lighting package will set you back a cool $895. It helps night vison immensely, but still does little to really reach out long distances into the dark off-road. For lighting up the immediate area around the Jeep, consider some aftermarket LED lights mounted to the front bumper or anywhere you need to see. For high-speed wheeling or if you want to see way out into the night, look for some spot beam HID lights.

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