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Answers to All Your Jeep Questions

Posted in How To: Tech Qa on March 13, 2018
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JK Axle Surprise

I've been getting Jp since I bought my first Wrangler in July 2016. I have a ’16 Rubicon Unlimited that I purchased new. I had a Rubicon Express 2.5-inch lift professionally installed right after buying the Jeep. I recently added 285/75R17 tires, Mickey Thompson Classic rims, and Rough Country front geometry correction brackets. I asked the shop to do a front alignment while there, and that's when the drama started. The shop informed me the camber specs were the worst they had ever seen. One side measured negative 1 degree and the other side negative 0.6 degrees. The tech said they normally only see something like this on Jeeps with lots of miles and wear. My Jeep only has 4,700 miles with no real off-roading at this point! You can see the slant of the tire on the passenger side with the naked eye. The shop is suggesting that I may have a factory defect in the front axle.

I immediately drove over to the Jeep dealer where I purchased it. The service manager took a look and said he had never had any problems like this come into the shop, even with lift kits. He checked the dealer network for anything similar and said nothing showed up. He wants me to bring it back in for his guys to put it on the alignment machine to verify the numbers from my local 4 Wheel Parts.

Have you guys ever heard of anything like this before, or do I have a one in a million fluke? Do I actually have a defective axle? Those front correction brackets couldn't have anything to do with camber could they? Any suggestions?
Brad Willett
Simsboro, LA

None of the suspension components you have added will alter the camber. Unfortunately, the camber is not adjustable on a factory ’07-’18 JK Wrangler. Typically, a camber problem results from abuse or worn components such as unit bearings or ball joints. An accident, jumping a Jeep, driving aggressively over rough trails, or hitting curbs and other obstacles hard could cause the front axle to bend, which would result in a camber issue. It’s not uncommon for the factory front JK axlehousings to bend under relatively sane off-road driving conditions, especially when larger aftermarket tires are added. The larger tires provide more leverage to bend the front axlehousing. Fortunately, there are many solutions. If you simply want to correct the caster problem, SPC Performance ( offers several different offset ball joints that can correct for up to 2 degrees of camber misalignment. This does not straighten the axlehousing, but it corrects the alignment until you can replace the factory front axlehousing with something more robust. Companies such as Dynatrac ( offer a bolt-in heavy-duty replacement axlehousing for the JK Wrangler Rubicon. The Dynatrac JK ProRock 44 features a beefier nodular iron centersection, larger-diameter axletubes with a thicker wall dimension, and stronger end forgings, which translate into a JK front axlehousing that will not bend like the factory housing. The beauty of the Dynatrac JK ProRock 44 axlehousing is that all of your stock Rubicon’s axle components—including the ring-and-pinion, bearings, locking differential, axleshafts, knuckles, unit bearings, brakes, and steering components—bolt right up to it. All you are replacing is the bent factory axlehousing.

Supercharger Solution

What is your opinion of the Spintex 3.6L intercooled supercharger system with tuner for the ’16 Jeep Wrangler? We’re talking about a lot of money and labor here.
Name withheld
Via email

Making more power is always hot on the minds of most Jeep owners. The addition of larger tires and wheels, heavy-duty axles, body armor, and other off-road accoutrements can weigh down a Jeep and decrease perceived power and performance. The felt loss of power from these additions is usually noticed most on-road. Off-road performance can usually be increased via the lower gearing afforded by the low range in the transfer case.

A supercharger is one of the most effective bolt-on performance parts available to increase usable horsepower and torque both on- and off-road. The supercharger kits for the Jeep six-cylinders typically cost in the neighborhood of $5,000-$6,000, not including labor. Even still, a supercharger kit is far less complicated and less expensive than an engine swap in all but very rare cases. Supercharger kits are essentially the last power upgrade step you can make before committing to a full engine swap and they usually produce and extra 80-100 hp, which is respectable. Supercharger kits do have their drawbacks though. Some supercharger kits require the use of more expensive high-octane fuel, and contrary to popular myth they do decrease fuel economy in most cases. It’s not uncommon for an aftermarket supercharger kit to drag the fuel economy of a well-outfitted Wrangler to 10-12 mpg. Most V-8 swaps will make more power and beat these fuel economy numbers, so you really have to think ahead and plan out where you want your Jeep in the future before plunking down your hard-earned cash for a supercharger. If you think that you’ll eventually make the jump to a V-8 engine swap, you might be better off saving your money for the V-8 conversion. If you think an engine swap is far too complex and expensive for you or your state has impossible smog laws, then the supercharger kits start to make a lot more sense. Many of them are 50-state legal and require little more than common hand tools for installation.

There are several supercharger companies to choose from if you do decide to boost your Jeep—these include Edelbrock (, Magnuson (, ProCharger (, Ripp Superchargers (, and Sprintex ( Also, Banks Power ( offers a turbo kit for the older Jeep 4.0L inline-six that provides similar performance gains. You may want to do a bit of research among the different brands to see which kit fits your needs best.


Having owned no less than 15 Jeep vehicles in my life, I have been away from the Jeep brand for nearly 15 years until December when I bought a new ’17 Wrangler JK. My first modification was going to be the addition of manual locking hubs. Imagine my surprise to find that no such thing is available for late-model part-time 4WD vehicles. Why not?

With so much emphasis on fuel economy, why would the factories not want some means of disengaging the front drivetrain? I suspect it might be because they would like the unknowing to assume that when you’re in 2WD, the front drive is somehow automatically disengaged. To have them know otherwise could be a damper on sales. In fact, one of my buddies assured me that his part-time 4WD Jeep did, in fact, automatically disengage the front driveline when you were in 2WD. Imagine his surprise when I had him look under his vehicle and watch the visible U-joint inside the steering knuckle as I coasted it slowly down a slight slope.

So what’s going on? I mean, if you don’t want to disengage the front driveline you can always leave the hubs locked in. Otherwise, for hard surface use or long trips, being able to disengage that mass of mechanisms you’re having to turn has to improve mpg. What am I missing in this new and confusing 4x4 age?
Dick C. Bostik
Thomasville, NC

Welcome back to the fold! Bolt-on locking hubs used to make a big difference in fuel economy. The drivetrain components that were spinning on older 4x4s were heavy and mostly unrefined compared to today’s standards. Unfortunately, simple bolt-on manual locking hubs have not been an option on short-wheelbase Jeeps since 1986. From an OE manufacturing and assembly standpoint, the traditional fixed spindles, wheel bearings, and manual locking hubs are a massive time burglar when compared to the modern non-rebuildable unit bearing. The unit bearing assemblies are easier and less expensive to manufacture and take far less time to install on an axle assembly. The introduction of unit bearings also included the use of an axle disconnect system. This system, found in YJ and XJ Jeeps features a two-piece axleshaft on the passenger side. The axleshafts are connected by a coupler that is engaged and disengaged via vacuum. When the axle is disconnected, the ring-and-pinion and front driveshaft do not spin, but the outer axleshafts, steering U-joints, and differential gears do. As this system aged and deteriorated it became problematic and left a bad taste in the mouths of most Jeepers. Some Jeep models, like the JK, TJ, and some XJs have no axle disconnect at all, and as you have noted, the axleshafts, ring-and-pinion, differential, and front driveshaft continue to spin in two-wheel drive on these Jeeps. The fuel economy gained by disconnecting these components is typically negligible at the consumer level. You’ll likely see less than a 1 mpg gain from a locking hub conversion on a newer Jeep JK because all of the components are designed to spin efficiently on the newer Jeep models. Even with a 1-mpg gain, a locking hub conversion would likely never pay for itself in fuel economy or component wear reduction on your JK.

Locking hub conversion kits are available for the JK, and they have other more important advantages than increased fuel economy. Companies such as Solid Axle ( and TeraFlex ( offer locking hub conversion kits for the JK Wrangler. The kits replace the disposable wear-prone unit bearings with more durable and serviceable wheel bearings that can be repacked and adjusted an infinite number of times. The design of the serviceable wheel bearings also makes them less susceptible to the leverage and wear caused by installing larger-diameter tires. Lifted JK Jeeps with odd front driveshaft angles will notice less driveline vibration after installing a locking hub conversion kit. Other advantages include the ability to unlock the hubs and disengage the front axle should something catastrophic fail, such as an axleshaft, steering U-joint, or ring-and-pinion. This capability alone would make it much easier to limp off of the trail and back to civilization.

Sealing 18

I am going to be resealing the oil pan on the Spicer 18 transfer case in my Jeep. I am having a difficult time finding the bolt tightening cross pattern. Any ideas?
Rick Philippi
Via email

The Spicer 18 is an incredibly robust, yet crude transfer case. The oil pan on the bottom of the Spicer 18 isn’t really a structural component, as evidenced by the thick gasket it uses for sealing, so tightening the bolts in a particular pattern is not all that important. The best method to keep the Spicer 18 oil pan from leaking is to use a factory-like thick gasket with generous beads of silicone on either side and around each bolt hole. Spicer 18 oil pan gaskets and complete gasket kits are available from companies such as Crown Automotive ( and Omix-Ada (

Start by prepping the sealing surfaces. Smooth the metal burs gently with a file and remove any old gasket materials with a scraper, wire brush, or other method. It’s not at all uncommon for the Spicer 18 oil pan bolt holes to become deformed from overtightening. You can flatten out the pan sealing surface around the bolt holes with a hammer and a small anvil. Let the transfer case drain thoroughly and wipe out the inside with a rag. Dripping oil from inside the transfer case can contaminate the sealing surfaces prior to installing your prepped oil pan. Clean the sealing surfaces with brake cleaner or solvent. Install the transfer case oil pan gasket with beaded silicon on the oil pan and hold it in place with two of the oil pan bolts on either end. Use the two bolts and bolt holes in the transfer case to line up the oil pan and start the bolts by hand. Lightly install the remaining oil pan bolts. I usually start from the center and work my way out when tightening the transfer case oil pan bolts, but there is no real pattern sequence that needs to be followed for a good seal. You can simply snug the oil pan bolts down or torque them to 15 lb-ft. For best results, let the sealant cure for 24 hours prior to refilling the transfer case.

If your Spicer 18 oil pan is bent up or damaged beyond serviceable use, you can purchase a new one from Kaiser Willys ( If you want something a little fancier than the stock stamped-steel transfer case oil pan, Novak Conversions ( offers a billet aluminum pan. The Novak Spicer 18 oil pan is machined from 6061 aluminum and adds rigidity to the entire Spicer 18 transfer case assembly. It also increases oil capacity by 16 ounces to help keep the internals well lubricated and cool.

Missing VIN

Where is the vehicle identification number located on a Willys CJ-2A?
Bob Seigfreid
Pasco, WA

Normally, the factory aluminum Willys CJ-2A VIN plate is found in the engine compartment on the firewall on the passenger side. It’s typically held in with four screws and measures about 4 inches long by 2 inches tall. Unfortunately, over the years they sometimes get moved around to accommodate other modifications such as heaters, engine swaps, rust repair, dual batteries, and who knows what else. We’ve seen the VIN plates corrode beyond recognition in wet climates, and it’s not at all uncommon for the VIN plate to simply be missing too. A lot can happen to a Jeep over the course of 70 years and numerous owners. There are other smaller VIN tags that can sometimes be found on the frame and body, but in most cases these are long gone. If your VIN plate is damaged or missing, don’t worry, companies such as Data Plates 4U ( specialize in replacing the hard-to find Bantam, Ford, Hotchkiss, and Willys VIN and data plates. The company can even stamp your correct VIN into the VIN plate prior to shipping. The correct mounting hardware is also available.

Flattie Throttle Swap

What is your favorite choice of cable junkyard gas pedal for flatfenders with a Chevy V-8 swapped in?
Via Instagram @cappaworks

As you have likely already found, building a flatfender is an exercise in problem solving for fitment of every component. I have gone so far as to letting the steering box location dictate what the rear pinion angle will be. The whole vehicle is a puzzle, and there is not a lot of real estate to work with when swapping in other drivetrain components. It would seem that a throttle pedal would be a simple junkyard component to find and install, but of course the flatfender body has its ways of making that difficult as well. Like everything else on a flatfender, comfortable throttle pedal placement will depend on several factors including transmission selection and location, seat selection and location, and your height. Personally, I’ve never found a comfortable junkyard throttle pedal assembly that simply bolts in and works perfect. The flatfender footwell is cramped, so the firewall location in reference to the seats makes it difficult to locate a traditional throttle pedal. Also, the sloped flatfender floor decreases the amount of room you have for the throttle pedal to cycle. If you do find a usable junkyard pedal, you’ll more than likely need to cut it up and modify it significantly for it to be comfortable and allow use of full throttle. For all these reasons, I’ve always found it less of a hassle to simply start from scratch and build my own throttle pedals when working on flatfenders. You’ll need to take the available space and comfortable foot placement into consideration. Sit in the Jeep with the seats and steering wheel installed prior to locating where you want the throttle pedal. There will be a lot of trial and error, but in the end you will have a comfortable throttle pedal that functions properly.

If you prefer to start with a complete junkyard throttle pedal, you might take a look at the Jeep XJ throttle pedal. I have used them on other projects with some success, but it will be need to be cut, bent, and welded on to work in a flatfender. There are also a few adjustable aftermarket throttle pedals that could work. The Lakester and Steel Spoon throttle pedals from Lokar ( look like they could be made to work in a flatfender without too much difficulty.

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