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Your Jeep - Answers to all your Jeep questions

Posted in How To: Tech Qa on July 15, 2016
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Liberty Solid Axle Swap
I have a ’12 Jeep Liberty KK, and want to do a solid front-axle swap. I am researching (with limited data available) whether or not using a JK axle will keep the KK computer happy. Supposedly, a JK axle is plug and play. As far as I can tell the KK unit bearings give the chassis computer speed and ABS brake info. Will the JK unit bearings also talk to the computer correctly, or will KK unit bearings work on a JK axle? I've read recently on a smaller forum that they will, but I’m not sure where he was getting the info from, or if it's just an urban legend. The article I read stated that the JK knuckles accepted the KK unit bearing. So if that is indeed correct, in theory I could run a 5-on-4.5 bolt pattern and keep the same set of wheels front to back. I would most likely have to run a spacer to correct for width. I am assuming that the JK has a wider track width. All the info I have found thus far came from a guy stating he had a spare JK Dana 44 in his basement. He was going through it and determined it would work. He could be very knowledgeable, or maybe not. The other solid axle swap I read about used 1-ton axles, so they lost the braking and traction systems I would hope to retain.

I’m ready to pull the trigger on my Liberty, but I kind of like having a speedometer and the traction control system. Even though traction control is kind of loud and funky, it does work for now in lieu of actual lockers. I'm not opposed to swapping out to a JK rear Dana 44, it's decent enough for my build to hold up, but I’m still open to other ideas.
Andrew Silveira

The ’08-’12 Liberty KK unit bearing assembly obviously has a different part number than the unit bearing assembly for a JK. Even though the spline count and other dimensions of the two unit bearings are similar, there are other dimensions that are not. The retaining bolt circle and hub pilot diameter are different. The JK hub bolt circle is 4.809 inches and the KK hub bolt circle is 4.768 inches. The JK hub pilot diameter is larger at 3.943 inches verses the KK at 3.622 inches. It would not be a bolt in swap, but it’s not insurmountable. It’s possible that some creative machining could produce an adapter collar to allow the KK bearing to a properly fit the JK knuckle. You’ll also have to alter the knuckle bolt pattern. This is not something you could accomplish in your garage without the use of a lathe and mill. Interestingly enough, the KK and JK brake calipers are the same part number and the brake rotors are very similar in dimensions (aside from the lug pattern). So that part of the swap should be feasible.

Sticking with the JK unit bearing in the JK axle looks doable as well. The ’08-’12 Liberty and '07-'14 Wrangler JK use the same rear wheel speed sensors, so that would lead me to believe they use a similar sensor and ABS ring up front, too. The wiring connected to the front sensor is slightly different, but the plugs and fittings look the same. You likely could put the Liberty sensor into the JK unit bearing, or simply plug the JK sensor and harness into your factory Liberty chassis harness. Either way should work. However, the JK has a 5-on-5 lug pattern and the Liberty has a 5-on-4.5 lug pattern, so the JK front axle will not accept the Liberty wheels. The simple solution is to get all new wheels with the 5-on-5 lug pattern and use wheel spacers/adapters in the rear. The other solution is to have the JK unit bearings machined for 5-on-4.5 wheels.

Considering all of this, I would stick with the JK unit bearings. Custom machining can be expensive. One-off custom-machined parts are also difficult to replace if needed, especially if you have a breakdown in the middle of nowhere.

Bad Bearing
I have a wheel bearing going bad on my XJ. The vibration is strong at 45 mph and lessens when turning left. Which side unit bearing should I replace?
Matt Higgins

If it is indeed a wheel bearing failure, I suspect it’s the left front bearing. When you turn left, the weight of the vehicle pushes more into the bearing on the right, so the left bearing gets a short reprieve. Regardless, you should inspect both front wheel bearings. You'll want to safely raise the front of the vehicle and grab each front tire at the 12 and 6 o'clock positions to check for slop in the bearings. Replace whichever bearing feels loose.

Death Wobble Monthly
What is your take on death wobble and the Jeep XJ? Everyone has ideas but nothing seems to work. What should the toe-in be set at?
Andrew Insinga

Questions about so-called “death wobble” cures have become one of the most common questions I receive from XJ, TJ, and JK owners. The suspension and steering systems on these Jeeps are all very similar in design. Death wobble and unpredictable shaky steering can be caused by many different things, even on a completely stock Jeep. It’s often caused by a combination of worn or loose steering and suspension components. However, more often than not, the problem stems from a track bar with worn ends or loose hardware.

Check the track bar ends and hardware very carefully. If you notice worn dirt or chipped paint circles around the mounting hardware, it’s probably loose. If they have been loose for some time, you’ll need to inspect the holes that the bolts pass through. The loose hardware will cause the boltholes to wallow out. No amount of tightening will keep the track bar in place if this happens. If the holes are wallowed out, you’ll need to either cut off and replace the brackets, or burn in some weld washer reinforcements. JKS ( offers heavy-duty weld-on replacement track bar brackets for several different Jeep models. Companies such as Low Range Off-Road ( and Ruff Stuff Specialties ( offer many different sizes of weld washers to repair wallowed out track bar and other suspension mounting holes.

The second most common cause of death wobble is worn drag link and tie rod ends. Again, you’ll need to inspect them closely for any slop. Make sure the pitman arm is properly seated on the splined end of the steering box sector shaft too.

The easiest and most effective way to check for slop in the steering system and front track bar is to recruit a buddy. With the engine off and the steering column unlocked, have your assistant saw the steering wheel side to side 1/8 to 1/4 turn while you look for unusual movement and loose hardware. Replace, repair, or tighten anything that looks suspect. You may need to check further downstream too. The steering shaft joints can wear and the shaft mounting can come loose.

In some cases, worn ball joints, wheel bearings, control arm bushings or loose control arm hardware can cause death wobble. Once you’ve inspected and repaired anything questionable in the steering and on the track bar assembly, you can focus your attention in these other areas.

I prefer to set the toe-in to 3/8-inch on most solid front axle Jeeps. This can usually be done at home with a tape measure.

If death wobble continues even after you are sure all of the components are tight and in good working order, you may need to install a steering stabilizer. We have found that in some rare cases, a stabilizer is the only solution. Don’t use a steering stabilizer as a cover-up for worn or damaged steering and suspension components.

Engine Swap or Not
I have an AMC 304 in my garage. If I’m correct, the AX15 transmission in my XJ has the same bellhousing pattern, so I’m thinking of swapping it in. Advance Adapters makes an engine mount kit for the 304 that uses stock YJ and XJ motor mounts. Other than the obvious things like wiring and plumbing, can you think of any issues I might encounter that could make me pull my hair out?
Justin Brodeur

The AMC 304 is not a direct bolt-in swap behind your AX15 manual transmission. You will need an Advance Adapters ( adapter plate kit (part number 712543J). The kit includes the adapter plate, a new clutch disc, a pilot bushing, fastening hardware and instructions. You will need to source an AMC bellhousing that was previously used with the Jeep T-150 or T-176 transmission. The bellhousing from a Jeep CJ-7 with an SR4, T-4 or T-5 transmission can also be used, provided that the bellhousing is drilled and tapped to match the adapter plate.

I often see many people make the mistake of thinking that because they already have the engine that it will be a cheap and easy swap. Realistically, the cost of the engine is usually less than half of the cost of the entire engine swap. Keep in mind you will need a new radiator, hoses, fan, fan shroud, motor mounts, power steering lines, exhaust, clutch, fuel system and more.

Once you get the carbureted 304ci V-8 in place, you’ll likely find that it performs more sluggishly than the fuel-injected 4.0L you replaced. Ultimately, I don’t think this is a very cost-effective engine swap. If the 4.0L in your Jeep is high-mileage and simply tired, you’ll be better off installing another 4.0L, in my opinion.

Sway Control
I have a 10-foot ATV trailer that I tow behind my ’11 two-door Wrangler Sport. I put my ATVs and all the camping stuff for about 10 adults and a few kids in the trailer. If the trailer gets to rocking on mountain roads, the Jeep will automatically engage the brakes. Is there something I'm missing? This will get your attention real fast. I almost got hit from the rear the first time it happened. I haven't been able to find anything about this auto braking system? I put a sway control bar on the trailer, and it has helped out a lot, but it still does it sometimes. Also, I was wondering if you have heard of putting on the rear coils from a four-door on a two-door for towing.
Corey Smith
Wittmann, AZ

What you are feeling is the ESP system kicking in. If the Jeep gets out of shape, with or without the trailer, the ESP system is utilized. It will reduce throttle and apply the brakes on different wheels to help straighten things out.

Keep in mind that the maximum trailer weight rating (TWR) for a ’11 two-door Wrangler with the tow package is 2,000 pounds. The ’11 two-door models without the tow package are rated for 1,000 pounds towing capacity. I suspect you might be near the maximum capacity, if not surpassing it, which should be corrected if so. To avoid erratic handling, you’ll likely need to drive much slower than normal when hauling a heavy load. The problem could be exacerbated by improper weight distribution in the trailer. The Wrangler is designed to have 10 percent of the maximum trailer weight as tongue weight on the trailer hitch. For a Wrangler without the tow package, that’s 100 pounds. The ’11 Wrangler two-door with the tow package allows for a 200-pound tongue weight. This may not be enough tongue weight in some situations. Too little tongue weight can cause erratic trailer sway, especially when floating the throttle downhill.

If you are staying within the tow ratings, there are a few things you can do to help reduce trailer sway in conjunction with proper tongue weight. The four-door rear coils will help some, as will firmer shocks at all four corners. You can also press the ESP button on the dash to reduce its interference. The system has three settings. Only full ESP and partial ESP mode are available when the transfer case is in two-wheel drive. There is also a way to completely deactivate the ESP system, but I don’t recommend going that route for safety reasons.

It’s sort of overkill for your small trailer, but you might consider the addition of a light-duty Curt ( weight-distributing hitch. Heavier front and rear anti-sway bars will make your towing platform more stable. Hellwig ( offers several different anti-sway bars for the Jeep Wrangler JK to improve on-road performance.

FSJ Disc Brake Swap
I have a ’71 Jeep J-2000 pickup and would like to use your front disc brake conversion ideas. Can you give me a list of the parts that I would need to do this? Is there a supplier that offers a complete kit?
Harry Bowker
Via email

Converting the early Jeep closed-knuckle Dana 25, 27, and 44 front axles from drum brakes to disc brakes is a fairly simple bolt-on swap. You can find the drum to disc brake swap story online here: "Drum to Disc Brake Swap Plus". Some of the factory frontend parts are retained, such as the locking hubs, stub shafts, spindles, and wheel bearings, but you’ll need a few parts to make the conversion. The factory FSJ closed-knuckle Dana 44 wheel hubs from the 11-inch drums will not work in most cases. You need wheel hubs with a machined backside. They can normally be found on Dana 25 or 27 front axles. Your wheel bearings or the Dana 25 bearings can be used. You’ll need the 1 1/8-inch-thick brake rotors and wheel studs from a ’77-’78 Jeep CJ, front brake calipers, brake pads, and caliper mounts from any ’74-’91 1/2-ton FSJ pickup or SUV, and flexible brake lines and banjo bolts that match the year of the calipers. Or you could save yourself all the trouble of compiling these parts and purchase a complete kit from companies such as BJ’s Off-Road (, Herm the Overdrive Guy (, and Parts Dude 4x4 (

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