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March 2012 Nuts & Bolts

Jeep Grand Cherokee Front Three Quarter
Ali Mansour
| Brand Manager, 4WD & Sport Utility
Posted March 1, 2012

Your Tech Questions Answered

What’s the Case?
Q: I finally decided to step into the 21st century with regards to my daily commuter. As much as I love the four-door JKs, the used ones are still really pricey so I have decided on a ’99-’04 Jeep Grand Cherokee WJ. They seem to have all of the modern amenities that will keep my wife and kids happy. Plus, I can cruise the highway at modern speeds without concern and they appear to have plenty of aftermarket support.

During my studies, however, I have come across a transfer case issue.

It seems the NV242 Selec-Trac is what I want. I like the traditional 2-Hi, 4-Hi, and 4-Lo, and the fulltime 4-Hi is just a bonus. What is the deal with the other options? I don’t understand the Quadra-Trac II. Fulltime 4x4 I kind of understand, but it must have some kind of lock for the differential for when I really want to go wheeling, right? Is there a way to lock it, or does it only lock up in low range? If the transfer case does not lock up, I am pretty sure I will hate it. It also really limits my Grand options because it seems like a lot of the Jeeps have this transfer case. So will I hate the Quadra-Trac II case, and if so what models do I need to be looking for to get the Selec-Trac option?
Steve Schissler

A: Out of the box the ’99-’04 Jeep Grand Cherokee WJ is an impressive wheeling machine. There were actually three 4x4 options for the WJ. The first is the Selec-Trac NV242 transfer case, which was standard on most six-cylinder Grand Cherokees. The NV242 offers 2-Hi, fulltime 4-Hi, 4-Hi (locked), neutral, and a 2.72:1 low range. While undoubtedly it’s a rare find, our research indicates that the NV242 was also an option with the V-8 in certain years.

The second, more common V-8 transfer case is the NV247 with Quadra-Trac II. The NV247 is a fulltime transfer case with a 4-Hi, neutral, and a 2.72:1 low range. In high range the NV247 sends most of the power to the rear wheels until it senses the front is spinning at a different rate. As the speed between the front and rear begins to differ greatly, hydraulic pressure builds inside the transfer cases differential, which engages a clutch pack and sends more power to the front. In low range it “locks” and splits power evenly between both axles.

The third configuration is the NV247 with Quadradrive. Quadradrive uses the same NV247 transfer case but adds Vari-Lok differentials inside of the front and rear axles. The Vari-Loks and NV247 transfer case use the same gerotor technology. This means when one wheel spins at a different rate, oil pressure forces clutches to engage and sends power to the wheel with traction. There are no buttons, levers, or switches. Everything engages automatically. The Vari-Loks are not lockers, but they are very effective traction aids, especially compared to an open differential.

When you factor in cost, performance, and ease of upgrades, the inline-six with the NV242 is a great option. Don’t be afraid to purchase a Grand with the NV247. If you are handy with tools and have a little extra coin to throw at the Jeep, swapping in an NV242 or NP231 transfer isn’t too terribly difficult. My advice is to find the right Jeep for the right price. All three 4x4 options work well off-road and, as you mentioned, have plenty of aftermarket support.

Bead Balance
Q: I understand the off-road benefits of beadlocks, but I’m curious if they are OK to run on a daily driven vehicle. I’ve noticed that most, if not all, of the Ultimate Adventure vehicles have beadlocks. Also, is there any special way to balance a beadlock and should I worry about any safety or legal issues running them on the street?
Vaughn Huffman

A: This is a great and very common question concerning beadlocks. As far as balancing beadlocks goes, there is no special way or trick. You can balance a beadlock the same way you balance a nonbeadlock wheel set. There are many old and new methods for balancing heavy off-road tires (stick-on weights, golf balls, tennis balls, BBs, sand, and so on). I suggest going to your local tire and/or 4x4 parts store that deals with off-road cleats and try what they suggest.

In regards to the safety and legality of beadlock wheels, there is a bit of a gray area. Beadlock wheels, with the exception of a few, are not approved by the Department of Transportation. Though some beadlocks adhere to DOT wheel construction standards, there are currently no specific regulations or test requirements in place for beadlock wheels. For this reason, most manufacturers sell beadlocks labeled for competition and/or off-highway use only.

Since beadlocks use bolts to secure the tire’s bead in place, they, like any other nut or bolt, have the possibility of coming loose. Just like you should periodically check your rig’s lug nuts, beadlock wheels simply require routine maintenance. Each rim manufacturer has specific torque requirements and suggested service intervals. I like to check mine after every wheeling trip and oil change. Some manufacturers even suggest swapping in new bolts each year on daily driven vehicles. The bottom line is if you are running beadlocks you need to inspect them frequently to make certain they are safe for you and others on the road.

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