Atas 2 speed vs Atlas 4 speed transfer case

[f1dotcom]

My 2000 4.0 AT TJ's 231 Transfer Case is on its way to the grave and I am looking to upgrade to an Atlas. Have 40s and running 4.88 gears at the moment.

I would like to have a good crawler and also be able to drive it on the road for short distances as well.


Would you recommend an Atlas 2 speed or an Atlas 4 speed transfer case? And why?

 

[Steel City 06]

If I could fit it and afford it, I would absolutely go for the 4 speed.

The biggest issue would be the rear driveshaft. Unless you have an LJ or are willing to stretch your wheelbase, you'd either have to get a very high articulation shaft or reduce the amount of downtravel by adding a limit strap to the center of the rear axle. But it could be worked around.

Do you have an auto or a manual transmission? If you have an auto, it may not be worth the effort. But a manual could be significantly improved by having extra ranges.

 

[Jerry Bransford]

If it's primarily for crawling and you're not climbing sand dunes or crossing mud pits requiring high wheel speed I'd think the 2-speed would be a good and less costly choice.

 

[Fouledplugs]

Atlas two speed based of the size difference between the two. A four speed would be great for crawling, if only it would fit.

The Atlas will have no issue on road just like it will be without issue off road. One could be swapped in a mall crawler and be fine with all the road miles.

 

[Jerry Bransford]

Atlas two speed based of the size difference between the two. A four speed would be great for crawling, if only it would fit.

Why would the 4-speed crawl any better since the 2-speed can be ordered with the same crawl ratio?

 

[Rescue6]

I have the Atlas 4 speed in my Tj. Had I not already had my rear stretch it would have been tough. But it went in great. I had 4:1 low range before and had times when I needed a range higher than that like the factory 2.72:1. To keep up in between obstacles but 1:1 was not low enough. I got the 4 speed with 3.8:1 so I now have.
1:1, 2.72:1, 3.8:1 and 10.34:1 ranges and 2 wheel drive rear wheel only in all of these ranges. I also have front dig in 3.8:1 and 10.34:1. I love the new case. I did not think I would ever use the 10.34:1. As I was really looking for the 3.8 and the 2.72. However I have come to love the control I have with the manual trans in the ultra low range.

 

[T_Hase89]

I wish I could give you advice... you know, without pictures of a TJ on 40’s, it’s impossible to tell you

 

[BugoutJeep]

I wish the Atlas 4 would fit better. I really wanted one, but it just seems very difficult. You can get it shorter by not running a speedometer signal from the tcase. I've got an extended fuel tank, so I can't massage the thing in too much.

If you went with a smaller fuel tank, maybe you could get yourself a couple of inches with your suspension setup, but I don't know. Personally I just decided to go Atlas 2 after I get my axles swapped out and add a locker. I'm going to try and see if I can still get the 6:1 tcase, but 5:1 wouldn't be bad either.

I've been trying to look into regearing the AX-15, but I haven't seen definitively how to successfully do that. There is supposed to be a way to get a 1st gear of ~4.1 and ~5.15. My engine is different, but 1-3 from the AX-15 aren't exactly what I'd want in a perfect world. If I could get a major granny gear and then a second gear close to what the current 1st gear is and then a slightly higher (2nd vs the AX-15 3rd) that would be my preference. That would let me take off in second without using the accelerator pedal and would remove a shift that doesn't do a lot for me in general. I think even with the 4.0 a different transmission similar to the Marlin 515 ( I think) would be a nice addition to most manual TJ owners.

On the other hand, a future build I want to do will be to take a wrecked YJ I have and stretch it and I'm going to try and to a doubler with NP-231 and Dana 300 (4:1) which would be ideal imo in a bunch of scenarios, but similar to the Atlas 4 in gearing. No idea if I can actually couple those 2 or not, but I thought I saw it done somewhere. Part of me wants to go for broke on that thing and get a TR-4050 with ~6.15:1 first gear, so 4.1x6.15x10.88.

 

[astjp2]

I wish the Atlas 4 would fit better. I really wanted one, but it just seems very difficult. You can get it shorter by not running a speedometer signal from the tcase. I've got an extended fuel tank, so I can't massage the thing in too much.

If you went with a smaller fuel tank, maybe you could get yourself a couple of inches with your suspension setup, but I don't know. Personally I just decided to go Atlas 2 after I get my axles swapped out and add a locker. I'm going to try and see if I can still get the 6:1 tcase, but 5:1 wouldn't be bad either.

I've been trying to look into regearing the AX-15, but I haven't seen definitively how to successfully do that. There is supposed to be a way to get a 1st gear of ~4.1 and ~5.15. My engine is different, but 1-3 from the AX-15 aren't exactly what I'd want in a perfect world. If I could get a major granny gear and then a second gear close to what the current 1st gear is and then a slightly higher (2nd vs the AX-15 3rd) that would be my preference. That would let me take off in second without using the accelerator pedal and would remove a shift that doesn't do a lot for me in general. I think even with the 4.0 a different transmission similar to the Marlin 515 ( I think) would be a nice addition to most manual TJ owners.

On the other hand, a future build I want to do will be to take a wrecked YJ I have and stretch it and I'm going to try and to a doubler with NP-231 and Dana 300 (4:1) which would be ideal imo in a bunch of scenarios, but similar to the Atlas 4 in gearing. No idea if I can actually couple those 2 or not, but I thought I saw it done somewhere. Part of me wants to go for broke on that thing and get a TR-4050 with ~6.15:1 first gear, so 4.1x6.15x10.88.

You can couple those two, you can also couple a NP203 and a 300 if the 203 is dodge. The 300 will need the bit output shaft and heavy duty gears to do 40's and not break things. That is why they oversized the atlas 2 because the original atlas was the size of the 300 and it was a little anemic in some situations so they upgraded it. You can also look at a Stak if they are still around. Good luck, Tim

 

[BugoutJeep]

2:1 and 4:1 and 8:1 might be extremely versatile.

 

[astjp2]

2:1 and 4:1 and 8:1 might be extremely versatile.

Having the correct transmission with a granny gear and 513's would also do the same thing with less options

 

[BugoutJeep]

Well what screws me is running diesel engines. To run on the road conveniently you really want to keep the diff ratio much smaller compared to gas engines since they don't like or need to be revved up. Off road I've really gotta look to my tcase for help. Most diesel engines come factory with a mated transmission with a much better granny gear than say our 4.0s came with ie ~3.83. 6:1 for a first gear would be ideal for every 4x4 diesel I've been around. I wouldn't be let down by 5:1 first gear either.

Sorry to derail the post.

 

[Fouledplugs]

You can also look at a Stak if they are still around. Good luck, Tim

Unfortunatly Stak is no longer around. You could find a used Stak, but I would avoid that.
There are billet cases for the 300. Adding the heavy duty input, heavy duty output, and low range gears in the 300 the weak point is the case. A billet case is the only solution for that.
Better route would be an Atlas IMO.

 

[BugoutJeep]

What u-joints would you all go with for the Atlas tcases? I've heard the 1310 will do better with the angles, but maybe not enough strength for these ultra low geared outputs.

 

[Fouledplugs]

Why would the 4-speed crawl any better since the 2-speed can be ordered with the same crawl ratio?

Have some common sense. Same crawl ratio? That is flat out wrong information. Common sense would tell you a 4 speed is going to give you more crwwl ratios than a 2 speed. You can get exclusive crawl ratios with the 4 speed that you cant with the 2 speed. Some of those gear ratios that the 4 speed offers are not available in the 2 speed.

Go build a 2 speed Atlas with any one of the ratios listed:
5.44:1, 8.16:1, 10.34:1, or 11.70:1.
You CAN’T. You can only get one of those ratios with an Atlas 4 speed cases.


Atlas 2 Speed Trail Series (small bearing)
Lowest Gear Ratio: 5.0:1
Atlas 2 Speed Pro Series (big bearing)
Lowest Gear Ratio: 3.8:1
Atlas 4 Speed
Lowest Gear Ratio: 11.7:1

That is unless their website is full of misinformation, in which I highly doubt.

 

[BugoutJeep]

Any idea if they still carry the 6:1 case? I've known people that have the 6:1 and I've seen it listed from 1 distributor, but not on the Atlas website. I don't want to bother them yet, because I'm probably a year out from getting the case.

 

[Fouledplugs]

Any idea if they still carry the 6:1 case? I've known people that have the 6:1 and I've seen it listed from 1 distributor, but not on the Atlas website. I don't want to bother them yet, because I'm probably a year out from getting the case.

Call them and ask. They dont list it on their website as an option.

 

[Big Moose]

Smoked my Teralow,looking to replace the 231 with a towable Atlas.

 

[Fouledplugs]

Smoked my Teralow,looking to replace the 231 with a towable Atlas.

What caused the Teralow failure?

 

[Big Moose]

I think just wear and tear. And the planetary gears came apart. They say an Atlas can be flat towed but not over 200 miles before it needs to be driven to lubricate. Have you heard that ?