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Your Jeep - July 2014

Posted in How To: Tech Qa on June 12, 2014 Comment (0)
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Verne Wants Your Jeep
I really enjoyed your article entitled “Driveway Differentials.” I have a ’50 CJV-35U (Editor: that’s a military version of the CJ-3A to you and me). I doubt I will ever completely restore it to the original military specifications, but I do wheel it. I installed a Lock-Right in the rear Dana 44 and installed a Dana 30 with a Detroit Truetrac in the front. I also added power steering, and Willwood helped me with the disc brakes in the front. Also, I have an overdrive for the Spicer 18 to help with the 5.38 gears. The old girl is powered by the original L-head 134ci flathead four-cylinder. Someday I would like to install an old V-6. This brings me to my question: would your axle conversion make sense for my Willys? I would also like to add a full-floating axle conversion, as I tow this Willys a lot.
Ernest Duskey
Via email

Ooh, the CJV-35U is one of my favorite Jeeps of all time. I want one. I’ve got my eye on one that’s gonna need some serious work. Actually, your axles sound pretty awesome, and it sounds like you have the differentials pretty well covered. If the Dana 30 you swapped in the front of the ex-military flatty has drum brakes, you could follow the advice I gave Nicholas in the June 2014 issue of Jp and swap over to discs. You could also upgrade to chromoly axleshafts in the Dana 30 if you ever plan on running 33-inch tires or larger and a V-6. As far as the rear axle, the only weak link in an early Dana 44 like yours is the two-piece axleshafts. The nut at the end of the axle can get loose and cause a failure when the Woodruff key hogs out its slot. The good news is that if you plan on adding a full-float axle conversion like the one available from ATV Manufacturing (hermtheoverdriveguy.com), you will eliminate this weak link. And as you mentioned, this conversion will allow the use of selectable locking hubs on all four wheels. That’s great for flat towing your Jeep. Just be sure to carry a spare locking hub or two on the trail, as that will probably become the next weak link in the rear axle.

Best Jeep Cherokee Suspension
Hi guys, I love the magazine. I read it cover to cover every month, so keep up the great work! I am building an ’00 Jeep XJ for my wife and kids to ride in. It is going to have a high-pinion Dana 44 front soon and is already running a Chrysler 8.25 in the rear. It is not going to be a hard-core wheeler -- just something capable-ish, safe, and reliable for the family. I also am a member of the Oregon division of Wheeling With Warriors and often have disabled veterans and their families ride with us. So minimal trail issues would be nice, as these events can be 70 or more vehicles in length and I would prefer not to be “that guy” who breaks down and holds everyone up. It will see a fair amount of expeditionary use because we go on week-long ghost town runs sometimes where the “roads/trails” can be less than predictable -- or sometimes non-existent.

It also has to have decent road manners, as it will see a fair amount of pavement going to and from these adventures. I plan on running an aggressive 35-inch all-terrain and trimming the finders to accommodate the larger tires. Here is my question -- I am torn between various 4- to 6 1⁄2-inch long arm verses a Y-link, three-link, or radius-arm setup. I would prefer to have as low a center of gravity as is within reason and some belly armor as well for peace of mind. So, the suspension will need to accommodate sub-frame connectors and skids. I could fabricate these things, but that would not be my first choice, as this rig will need to be safe at speed for everyone, whether in our rig or not. Brand names aside (or not, if one stands tall amongst the others), what setup would you suggest for the intended uses of this vehicle?
Jakob Belles
Via email

Generally speaking, when it comes to a suspension lift, you get what you pay for. We’ve had pretty good luck with Jeep XJ suspensions from Rubicon Express, BDS, Clayton Offroad, and TnT Customs. If I were you, I would try to keep the suspension lift amount below 4 1⁄2 inches or so. You can do this in an Jeep XJ with proper fender trimming and the right bumpstops front and rear and still fit 35s. Generally, any suspension lift over 31⁄2 inches will require either front control arm drop brackets or a front long-arm conversion, or the ride can be harsh and jarring. Other things to consider are that you will almost certainly want a slip-yoke eliminator for the NP231 or NP242 your Jeep XJ has. Add in a new double-cardan rear driveshaft, and your driveline will be happy and vibration free. As far as belly armor, there are several options. Look for skidplates made of 3⁄16- or 1⁄4-inch steel plate that span from one pseudo frame rail to another. You are also going to want some rocker guards, a gas tank skidplate (the factory one is pretty good), possibly some thick diff covers front and rear, and maybe an upgrade to the steering on your XJ. We could keep going, but that ought to give you a pretty good start on a reliable safe Jeep XJ for any trail.

Which JK
Been a reader of Jp for 14 years or so. I appreciate all that you and your team do to feed my Jeep addiction each month. Love your no-nonsense approach to the sport and lifestyle of wheeling.

I have a question. It’s about time for me to upgrade my beloved TJ with something that fits the growing family at little better. Like most of us, the budget limits what I can spend for a newer/bigger Jeep, so I’m looking for some advice. I could buy an older JK Rubicon (’07-’11) with the 3.8L engine and have all the built-in factory off-road prowess that I’d like to have, but I know that the 3.8L engine pretty much sucks in a four-door JK. Or, I could probably swing for a newer ’12-ish JK Unlimited if I stick to the “Sport” package. I’d gain the great 3.6L engine, but lose the better axles, gears, and lockers found in the Rubicon. Given your experience as an editor and driver in both eras/grades of vehicle, what would you suggest? The Jeep would see daily freeway driving duties and weekend wheeling. A 3-inch lift and 35s would be the extent of my modifications.
Jeremy Oviatt
West Jordan, UT

Wow, quite the conundrum there. A JK Unlimited Rubicon would be a pretty sweet replacement for your TJ, but the 3.8L hauling around all that Jeep on 35s is gonna bring the suck even with the 4.10 gears available with the Rubicon package. The 3.6L Pentastar is much better suited to the task, but has only been around for a few years so longevity of this engine is not fully known (until consumers get 200k plus miles on these things). We know the 3.8Ls tend to have issues at 90k, 150k, or if you are lucky, 160k. Also, technically the rear axle in a ’12-’14 JK Sport is going to be the same 30-spline Dana 44, although not with the Rubicon’s locker or 4:10 ratio. The front axle in a JK Sport is going to be a pretty decent Dana 30 that should hold up almost as well as a Rubicon Dana 44 front, and when, it built could be made to last under a lightweight JK with 35s. Both axles are going to have similar problems under a porky JK Unlimited -- that is, they will bend and brake if beaten on when wearing 35s. I’m willing to bet that a ’12-’14 JK with the 3.6L and the optional 3.73 gears is gonna drive better than a ’07-’11 JK Rubicon with 4.10s on-road with similar sized aftermarket tires and lift. Off-road, the lockers and 4:1 NVG241OR are gonna make the 3.8L powered Rubicon stand out, but lockers aren’t everything off-road unless you plan on beating this thing in the heavy rocks, mud, and sand. The best recipe to follow is to go drive both on dealer lots and decide what you like best. Then, after purchasing your Jeep, build it with parts designed to be as light as possible while still providing strength. It’s easier to save weight than to make more horsepower. If you choose the 3.6L-powered Sport, know you can always regear the axles, T-case, and add lockers later on down the road.

Jeep XJ With a Stutter
First, I want to say I love your magazine. I’ve been a Jeeper for about 30 plus years. Finally got my favorite: an ’01 Jeep XJ. I mostly use the Cherokee for wheeling in the desert of Southern California and also for hunting. I have had CJs, a -5, a -7, and an M38A1. Here’s my problem. The 4.0L runs great except when I drive long enough to go over 210 degrees and shut it off. If I let it sit for any length of time and allow it to cool down, I have no problem. But if it sits only for a short time, when I start it up it will idle with a miss for a short time, but then clears up. At that time, it throws a misfire code on the number three cylinder. I’ve replaced the coil pack, and the problem is still the same. I swapped injectors between the number one injector and the number three injector, and the misfire code still shows the number three injector as the problem. The spark plugs are all burning perfectly, and the Jeep is not using any oil. I’m kind of lost.

Anyway, I’m a wheeling fool and sure love that Jeep XJ. So far it has a 4.5-inch Rubicon Express lift with a locker in the front. A Warn 9,500lb winch sits on a heavy-duty front bumper, while the rear heavy-duty bumper has a tire carrier.
Name withheld
Via email

So what you have here sure sounds like a fuel-injector heat soak issue that was actually a TSB (technical service bulletin) for ’99-’01 Jeep XJs (and some 4.0L-powered Grand Cherokees). The Jeep dealership will happily sell you a little tube-shaped heat shield that you have to cut to length and place around the number three fuel injector. The part number is: 56028371AA Ignition Wire Shield. This should help. It worked for the ’01 Jeep XJ that I owned. Also, adding hood louvers or small 1⁄2 to 1-inch spacers under the rear hinges of the hood creating a pseudo cowl induction hood may also help dissipate heat.

We’ve seen the ignition wire shield get soaked in oil, which renders its heat shielding properties useless, so if your Jeep XJ already has a shield installed and it’s grimy and old, a new shield may help.

College Kid With Nothing To Do?
I’m a college kid with nothing to do, so therefore I turned to my Jeep for entertainment (yeah, I know, weird statement about college). I started thinking about a few different ways to do things and want to know if they would work or if I’m just thinking of new ways to break my Jeep. First, my Jeep is an ’88 Wrangler with the vacuum center axle disconnect front axle. Would it be possible to put a mini spool in it and then buy the one of those selector cables for the central vacuum disconnect and have a selectable locker? Second, I work in a performance car shop, and I see a lot of ladder bar suspensions. Would it be possible to run a ladder bar suspension front and rear with coilovers and a track bar? Is this doable, or am I just thinking of a new way to kill myself on the interstate? It sounds good to me, but what do I know? I’m just a 19-year-old kid who thinks he knows everything (at least that’s what they tell me).
Elliot
Newport, NC

Hmm, when I was a young lad in college I was too busy with homework, studying, beer consumption, studying beer consumption, beer-related homework, social activities, and beer-involved social activities to do much actual Jeeping, but when I could, I went wheeling. Personally, I am glad you are thinking about Jeeps when you are not thinking about college. It’s probably better for you than spending as much time with beer as I have. All in all, I’ve spent lots of time in school, and towards the end of my career as a college student, I finally mastered the place. Once you have learned how you learn, you can master any (or almost any) subject. You then have a powerful tool at your disposal that almost no one can take away from you, no matter what the future holds.

The answer to your first question about the mini spool and a 4x4 Posi-Lok is actually one I’ve run across before. Hypothetically, it would act kind of like a selectable locker in that the two front tires would not be fighting each other on turns when the Posi Lock is disengaged. Only in this situation the driver-side axle and wheel would always turn when 4-Hi or 4-Lo is engaged even with the Posi Lock disengaged. This would still cause binding between the front and rear axle since they are traveling different distances around a turn. On a hard surface, that would put a lot of stress on that one short axleshaft and U-joint in the front axle. I’m willing to bet you would break that axle or U-joint frequently. Also, when on-road, your front driveshaft would be forced to turn all the time because of the spool, while an open diff and a functioning center axle disconnect allows the driveshaft to remain stationary while in 2WD. That rotation of the driveshaft could cause a vibration or extra wear on your driveshaft U-joints. In short, if you plan on driving your YJ on the road much, I would not run a mini spool and a 4x4 Posi-Lok. If it’s a trail rig and you are alright with carrying plenty of spare shafts and swapping them out, you might be able to pull this off.

As for your question about suspensions, now is probably a good time to start educating yourself about different kinds of link suspensions. What you are describing with ladder bars and a track bar would, if I understand correctly, be pretty similar to a two-link (with track bar) or a radius arm suspension. These types of suspensions can be made to work on a Jeep like yours, but there are drawbacks that make them less than ideal. For example, the axle ends of the ladder bars/radius arms will fight each other as the axle articulates. Luckily, there are other options for you to research. In fact, as part of your new Jeep-related homework (since you have so much free time, wink wink), please write a brief synopsis of the benefits and drawbacks of three-link and four-link suspensions with track bars, due Monday. Then you can move on to studying triangulated three- and four-links, and double triangulated four-links. Lastly, I’ll say this: If I were you, I’d take some engineering classes and maybe tinker with your YJ’s leaf spring suspension for now. There are several ways to get the leaves on a YJ to work pretty well off-road without reinventing the wheel. Once you have more knowledge of link suspension and engineering, you can dip into the realm of building your own linked suspension systems if you want.

4.0L Cam Difference?
Do you know if the Chrysler cam for an ’06 4.0L would be set up with the hole for the spring and button such that it would work in an earlier engine? The parts guy at my local Jeep dealership is a computer reader and insists that cams for my ’98 from Chrysler are no longer available. He doesn’t know if the hole is correct on the later camshaft for earlier engines, and he doesn’t care to check for me.
Steven L. Messer
Via Facebook

You are correct. The cams for ’00 (maybe late ’99) through ’06 4.0Ls are different from earlier (’87-’99) 4.0L camshafts. The timing chain is different, as is the method of mounting the timing gears to the front of the cam, so the newer cam won’t work in an earlier engine. I confirmed this with Zach at 505 Performance (505performance.com). The crew at 505 Performance can help you out with a cam for your 4.0L no matter what year it is, even if the dealer can’t.

Write Us!
Got a tech question you’re just itching to get answered? Send it on in to Jp Magazine, Your Jeep, 831 S. Douglas St., El Segundo, CA 90245, or e-mail it to verne.simons@jpmagazine.com.

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