Lower gearing is a pillar of off-road performance. It allows the engine to turn bigger tires more easily and move your 4x4 over trail obstacles. But adding gearing has often meant expense in axle gears or transfer case replacement as well as driveshaft adjustment. With Advance Adapters' new RubiCrawler for Jeeps with the 42RLE overdrive automatic transmission, you can now multiply your Jeep's low-range gears after a short day's work of installation. Even better is the fact that no driveshaft modification is needed, as the RubiCrawler literally replaces a big empty space in the tailhousing of the transmission.
With this new reduction box in front of the Jeep's stock transfer case, your choice of low ranges effectively doubles or triples (see caption 6 for info; 1-1 isn't a low range, but it is a choice), depending on whether you have an NP231 or an NP241 Rubicon case. Either way you'll now have gearing for a variety of off-road terrain.
 1. The RubiCrawler is a simple...  1. The RubiCrawler is a simple six-pinion planetary reduction gearbox with an aluminum case that has either 1:1 or 2.72:1 gearing available. This is very similar to the reduction box found in front of the four-speed Atlas. |  2. Jeeps from 2003 to today...  2. Jeeps from 2003 to today are available with the four-speed automatic 42RLE automatic transmission, including TJ and JK Wranglers and some Libertys, and Dodge Dakotas and Nitros. An ingenious engineer at Advance Adapters realized that the tailhousing of the 42RLE served absolutely no purpose. It didn't hold any gearing and only had a small line for an oil return. That line is kept with the new RubiCrawler box. |  3. Both the tailhousing and...  3. Both the tailhousing and the RubiCrawler are roughly 7 inches long. This means everything stays in the stock location, with no driveshaft changes required. |
 4. The installation of the...  4. The installation of the RubiCrawler can be done in a day with two people and the proper tools. All it takes is removing the skidplate, crossmember, driveshafts, shifter, and transfer case. Advance Adapters also offers the Uni-Raise, which hangs from the framerails and supports the transmission while the crossmember and transfer case are removed, making the job much easier. |  5. The stock shifters are...  5. The stock shifters are replaced with a dual cable shifter, one for the RubiCrawler switching from high or low range, and the other for the transfer case shifting from 2WD, neutral, 4-Hi, and 4-Lo. |  6. When you're installing...  6. When you're installing in front of a TJ or JK New Process 231 or NP241, you have the option of 1:1, 2.72:1, and 7.40:1 gearing. Put the RubiCrawler in a Wrangler Rubicon with the NP241OR Rocktrac transfer case and you have 1:1, 2.72:1, 4.0:1, and 10.88:1 gearing available. |