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STaK 4x4 Monster Box Transfer Case - The Big 3

Posted in How To: Transmission Drivetrain on January 1, 2006
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When it comes to wheeling, options rule. There is a new player in the transfer-case aftermarket, and the new STaK 4x4 three-speed Monster Box has more options than anything else currently available. Wondering why you would need a three-speed transfer case when your stock two-speed has worked great up until now? The multiple ratios give your 4x4 the ability to explore different terrains. In the rocks, drop it into 5.44:1 low range and crawl to your hearts content. Need a little more wheelspin for the dunes or mud? Shift up into the midrange of 3.05:1. When it's time to go home you still have the standard 1:1 high range for highway speeds.

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The STaK unit is a smart upgrade for those four-wheelers who visit a wide variety of terrain, yet still want or need to do street driving, or those who have built their truck specifically for one terrain, but now want to explore something new. It allows you to run higher axle gearing so that at highway speeds you are not spinning the engine at excessive rpm, yet still offers the control of granny gearing for slow descents and technical climbs. Having multiple gearing choices is especially useful if your 4x4's engine doesn't have a lot of power or a wide powerband since you can make up for it with torque multiplication when needed.

There is one major downfall of the Monster Box: It's a monster. Weighing 153 pounds, this beast is more than twice the weight of a stock Jeep Wrangler NP231, but with all that weight comes gears that dwarf stock Jeep parts.

So is it worth it? As this story goes to print, the Monster Box is listed at $2,800, and though it is new to the market, the folks at STaK have been testing it under their personal vehicles with great success. If you're looking for options, this is definitely one with many options inside.

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PhotosView Slideshow

Here is the biggest issue we found with the Monster Box: its sheer size. In fact, the STaK team has found that using their forklift to help install the case in a stock Jeep TJ is much easier than having two guys bench-press 150 some pounds up and onto the transmission. We're slightly concerned about all that weight hanging off the tail of an aluminum manual or automatic transmission, but there have not been any issues thus far. STaK is working on a new mounting unit to better support it. However, the case can be mounted in 25 different clocking positions in 4-degree increments for nearly any 4x4 you are building.

The Monster Box fits in a Jeep just fine, and though STaK won't make any claims about its strength, it seems more in the size range of a fullsize truck NP205 rather than a 11/44-ton Jeep transfer case. When installing in a Jeep you will need to shorten the front driveshaft 2 to 4 inches and get a new rear driveshaft. Though designed with Jeeps in mind, the Monster has adapters available for nearly any transmission you would want to put it behind. We would like to put one in a monster fullsize truck with huge tires and some serious engine or a crazy all-around trail buggy. Heck, we'd even consider one for our daily driver/weekend warrior 4x4. With a case this beefy and with so many gearing choices, the options are endless.


Stak 4x4
El Paso, TX 79936

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