392 transfer case swap?

[Chris-AZ]

I’ve come to the conclusion that the stock transfer case is fine with the torque of the 392 and the torque converter multiplier. So far have never needed a lower gear. I do have the XR oem 4.56

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[1996cc]

I’ve come to the conclusion that the stock transfer case is fine with the torque of the 392 and the torque converter multiplier. So far have never needed a lower gear. I do have the XR oem 4.56

The torque and gear ratios are not a problem. When the clutches start unlocking on you and/or slipping, then you’ll realize the need for the atlas in the 392.

 

[Tank2112]

I’ve come to the conclusion that the stock transfer case is fine with the torque of the 392 and the torque converter multiplier. So far have never needed a lower gear. I do have the XR oem 4.56

The issue is for those that want a 3.5" and/or higher lift to run larger than 37" tires on a Wrangler 392. Regular JL's can simple simple run in 2-wheel high and could run manual locking hubs to completely disengage the front driveshaft. With 392 being AWD, you can quickly get vibration from front driveshaft with much lift. For some reason aftermarket driveshaft companies are not making true CV (ball bearing style) jointed driveshafts, that I've heard of? U-joint style driveshaft tend to wear quicker and create vibration if at much of an angle. I saw a video that showed the pulsing rotational speed a u-jointe creates in a driveshaft when at an angle. More the angle, the more the surging that causes felt vibration.
Seems someone would make a true CV style driveshaft (not the commonly mistakenly called CV double u-jointed driveshaft, which is not a true CV joint. Again, a true CV joint is a ball bearing style joint, like currently used in front axles of the full-time 4wd 392 Wrangler. Secondly, they are stronger than a standard style u-joint, especially when at an angle. Toyota has used ball bearing style CV joints for years in their front axles. As most know, RCV uses CV joint in their axles. True CV axles rotate at same speed whether straight or at full turn, without rotation surge. Surge=vibration.

 

[Tank2112]

I suspect/hope that in time, for 392 Wrangler owners that want to run a higher lift, the go-to replacement transfer case for the current AWD will be the regular JL Rubicon NV241 Rock-Trac. However the computer will be looking for AWD without modification/reprograming. Another issue is, with the torque from the 392, you don't need the lower 4:1 ratio. Many times a little more wheel speed is beneficial to get over or through that obstacle. Especially with our current 8 spd auto transmissions. In a perfect world that low range could be re-geared to match the 2.72:1 to 3:1 ratio. With the older 4.0L TJ's with manual transmissions, rock crawling one could argue the need for control from the lower ratio.
Atlas makes a great t/c, no doubt. One of the best for a rock buggy. For most where our $100k Jeeps are more of a daily-driver/weekend-warrior... benefit can come from quiter/smoother synchronized gears. In the 15+ years of running an Atlas 4-spd in my LJ (Hemi 6.1, 5-spd auto), I seldom benefited from the 2-wheel front only turn. Even with 44" Pitbull Rockers or 42" Comp Treps, I found that when I could really benefit, I usually didn't have the traction to move the Jeep with just the front tires. Sounds cool though.

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