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Advance Adapters Rubicrawler Kit

Posted in How To: Transmission Drivetrain on August 1, 2010
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We love that the factory Wrangler Rubicon offers a 4:1 transfer case, but the truth is that in most wheeling situations short of the Rubicon Trail or Moab, we often find that "Lo" is too low and "Hi" is too high. If this has been your experience with your 2003-to-2010 42RLE-equipped automatic TJ or JK, Advance Adapters has just the solution for you.

Called the RubiCrawler, this six-gear planetary reduction box replaces the hollow tailshaft of your 42RLE four-speed automatic transmission. Because it is the same length as the tailshaft that it is designed to replace, there is no need for any driveshaft or crossmember modifications. The RubiCrawler has a 2.72:1 low-range and works in conjunction with any Atlas transfer case, standard transfer case, or the Rubicon's 4:1 Rock-Trac case.

The benefit of the RubiCrawler is that it increases the flexibility of your gearing in order to better tailor your Jeep to the terrain you are traversing. For instance, a Jeep Rubicon equipped with the RubiCrawler can be used in 2-Hi (normal, 1:1), 2-Lo (RubiCrawler, 2.72:1), 4-Hi (normal, 1:1), 4-Hi (RubiCrawler, 2.72:1), 4-Lo (normal, 4:1), and 4-Lo (RubiCrawler, 10.88:1). Not only does it split the difference nicely between the factory low- and high-ranges, but it gives you the super-low range for extremely technical trails. If your Jeep is equipped with an NP231 or NP241 transfer case with the 2.72:1 low range, your options are 1:1, 2.72:1, and 7.4:1.

The RubiCrawler is a 7-inch-long aluminum case that replaces the empty tailhousing at the rear of the 42RLE transmission. It offers 2.72:1 and 1:1 gearing, and works in conjunction with the stock transfer case and transmission.

No longer will you find yourself over-revving while trying to keep up with your friends on the trail between obstacles, nor will you find yourself with not enough gearing in the most challenging terrain. And with a retail price of $1,595, it is probably one of the top upgrades for the money and one of the best gearing options going for any vehicle.

We snapped some pictures of a RubiCrawler installation on a TJ while we were shooting another install at Off Road Evolution in Fullerton, California. Check out what goes into gearing down your Jeep with the RubiCrawler.

P/N 42R800
What we didn't show you in this install is the optional wiring harness that Advance Adapters offers for JK Rubicon owners (P/N 42R800). What is special about this harness is that it allows the locking differential, electronic disconnecting sway bar, and the electronic stability program to operate like stock when the RubiCrawler's low-range is engaged, regardless of the status of the stock transfer case. For only $105 retail, it is a nice additional feature at a very reasonable price.

PhotosView Slideshow
PhotosView Slideshow


Advance Adapters
Paso Robles, CA 93446
Off Road Evolution
Fullerton, CA 92833

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