Reasons we chose this product:

  • Tired of breaking T-cases

  • 3.8 to 1 crawl ratio

  • 32 spline upgrade

  • Better clearance and driveline angle


    Installed on Chris's Jeep


Well, this is the big one.  If you're going to play with the big boys, this is definitely a huge leap in the right direction.  There's no going back to the world of stock after completing this step, so here we go:


Chris is one of those people who learned a long time ago that when something breaks, you don't simply replace it with another one of the same caliber, you take the opportunity to upgrade.  You spend the extra dough and buy one that will last.  Of course this kind of upgrade is like trading your .22 in for a Howlitzer.


If you haven't yet had the pleasurable experience yourself, trust us that your transfer case is against you.  From the very moment you altered anything one your Jeep, I don't care if was your mirrors, your t-case has had it in for you.  Check your warranty and you'll find that once you change any stock suspension part on your Jeep, your t-case is no longer covered.  That's because Jeep knows their t-case wasn't made for any kind of angles, and being that your driveshaft is only around 15 inches long, it's already almost maxed out.  To prove this point I invite you to take a peak inside our garage at the 3 transfer cases sitting in a pile all trashed in some form or another.


Clearance and Angles:

When you do put your lift on your Jeep, you'll notice that not all of your Jeep goes up in the process.  Just about every suspension lift comes with spacers that you'll have to put between your center skid plate and the frame so the driveline won't be at too severe of an angle.  If your planning on offroading a lot, this can defeat the purpose of trying to gain additional clearance.  These guys over here get hung up on their belly almost more than any other part, and we've had to replace one skid and pound the crap out of the other to take out all the dents.  There are many kits on the market that allow you to actually lengthen your driveline, thus decreasing the angle needed to reach your rear differential.  This is accomplished by shortening the output shaft on your t-case converting it from a slip yoke to a fixed yoke.  The Atlas II also offers this benefit enabling 6 extra inches of room for a longer driveshaft.  Because of this reduced angle, you can kiss those spacers goodbye and get that skid back up where it's supposed to be.


You'd think an inch-and-half solid steel shaft would be indestructible; not so.  Chris found a way to snap his and had to be towed out off of a trail.  Not only does the Atlas come with a shorter shaft (2.5in shorter than a SYE conversion shaft), but it is thicker and and a larger spline count thus strengthening it even more.

Chain vs Gears:

Your stock NP231 also has another weak point: It is driven by a chain.  The problem with this is that with time chains tend to stretch (remember your childhood bike?).  The Atlas on the other hand is all gears stacked upon gears; much more dependable and less likely to feel the effects of time.




Now we come to the greatest benefit the Atlas has to offer, it's very low gear ratio.  AA offers a few models each with different gearing options.  The better the gearing, the better the crawl ratio.  The better the crawl ratio, the easier it is to control your Jeep while rock crawling and it enables you essentially point your Jeep at an obstacle and let it do what it was made to do and pull itself up and over with minimal need for throttling.  The important factor in choosing which gearing to go with, is determining what is best for your Jeep and your needs.  If your Jeep is a manual transmission, you may want to go with AA's Extreme Low 4.3:1.  But if your Jeep is an automatic, it would be safer to go with the Ultra Low's 3.8:1 or the 3.0:1.  This is because with the amount of pulling power the Atlas provides you with, it can in turn make it harder to slow or even stop your Jeep.


Here's what Chris's ratio was like and what it will be when we're done:

1st gear (auto) T-case Low Axle Gear = Crawl Ratio
Stock 2.74 2.72 3.73 = 27.79:1
W/ Atlas 2.74 3.77 3.73 = 38.5:1



Now by looking at this chart, you should have no more doubts about the benefits of the Atlas II.  I mean come on people it's clear that 38 is a bigger number than 27.  And now the numbers are red instead of black.  That's gotta be worth something.


Anyway, enough boring number jibberish, on to the install.