I have seen the light and I want to get a 4:1 ratio transfer case

Stinkbug

TJ Enthusiast
Original poster
Lifetime Supporting Member
Joined
Apr 9, 2016
Messages
617
Location
Huntington Beach, Ca
Over the weekend, I had the opportunity to experience the difference between my NP231 transfer case with a 2.72:1 ratio and a transfer case 4:1 in the rocks. I want to make a change but welcome the collective thoughts of this beehive of user knowledge.

A bit about my Jeep:

  • 1997 Sport 4.0
  • 32rh Transmission
  • Dana 30/Dana 44 that are locked and trussed with 30 spline chromoly axles. They are geared to 4:56.
  • Black magic 15” brake kit.
  • Custom belly-up skid.
My use case for my Jeep
  • What I do - My Jeep lives tucked into the garage corner. It comes out to explore the southern California mountains and desert. I run on everything from fire roads and mild trails to the Rubicon Trail, Moab, Johnson Valley, etc. I most enjoy the rocks. We love to drive it around town in the spring and summertime and don't want to decrease that pleasure significantly.
  • What I don't do - I do not intentionally take my Jeep in the mud. I actively avoid it and always will. I do not play in the dunes and have no desire to.

My random thoughts and questions that I have pieced together so far…
  1. I see two obvious ways to reach a 4:1 ratio: a 241 transfer case or an Atlas 2-speed. I am leaning towards the Atlas for the additional capabilities of a front dig in particular *Edit: The comments are putting more emphasis on this than my real world use will (and just because I can).
  2. However, I am unsure if one approach or another requires significantly more cost or effort.
  3. I see the Atlas is available with a 4:3:1 or a 5.0:1. Will the 5.0 be overly limiting when it comes to the time on the trail spent in between major obstacles where 4hi is too high and 4 low (with 5.0 ) is too low and slow?
  4. I seem to run across more Atlas conversions than 241 conversions. Any idea why? I believe it is likely related to item #2.
  5. I understand the swap will produce significantly more stress in the drive line. Given my setup (see above), what will likely be my new failure point?

I am always trying to think ahead about the cascading effect of upgrades to my Jeep, but I sometimes miss the obvious. In your opinion, what am I missing? Why would I not want to do this?
 
Last edited:
  • Love
Reactions: Woodrow
241 doesn't have much for factory support and parts.plus people seem to think they are worth most of the cost of an atlas.That would tip me towards an atlas.

Doing front digs with any ratio would make me think your front shafts and ujoints would be likely weakest points
 
Doing front digs with any ratio would make me think your front shafts and ujoints would be likely weakest points

I watched a vid on YT where a guy was doing the front dig function on a bronco literally every time he had to turn around. I don't know if CV joints are less sensitive to angles but I would be doing that very sparingly on a Jeep with u joints axles.
 
  • Like
Reactions: Rickyd
Over the weekend, I had the opportunity to experience the difference between my NP231 transfer case with a 2.72:1 ratio and a transfer case 4:1 in the rocks. I want to make a change but welcome the collective thoughts of this beehive of user knowledge.

A bit about my Jeep:

  • 1997 Sport 4.0
  • 32rh Transmission
  • Dana 30/Dana 44 that are locked and trussed with 30 spline chromoly axles. They are geared to 4:56.
  • Black magic 15” brake kit.
  • Custom belly-up skid.
My use case for my Jeep
  • What I do - My Jeep lives tucked into the garage corner. It comes out to explore the southern California mountains and desert. I run on everything from fire roads and mild trails to the Rubicon Trail, Moab, Johnson Valley, etc. I most enjoy the rocks. We love to drive it around town in the spring and summertime and don't want to decrease that pleasure significantly.
  • What I don't do - I do not intentionally take my Jeep in the mud. I actively avoid it and always will. I do not play in the dunes and have no desire to.

My random thoughts and questions that I have pieced together so far…
  1. I see two obvious ways to reach a 4:1 ratio: a 241 transfer case or an Atlas 2-speed. I am leaning towards the Atlas for the additional capabilities of a front dig in particular (and just because I can).
Be aware that a front dig can put a lot of torque fully delivered to the front components ONLY. You can do one, you need to be very judicious in how and when.
  1. However, I am unsure if one approach or another requires significantly more cost or effort.
Atlas is more effort. I forget what belly skid you have?

The 241 requires a digital speedo correction device. Atlas doesn't but we run one anyway.

Atlas is shorter. You can't shorten the 241 with a SYE since it is flange mount. Converting from flange to yoke only buys a quarter inch longer rear driveshaft.

You're buying new driveshafts for both swaps, so that's a wash.

The floor plate where the t-case shifter is will need some work. We are currently installing an Atlas in a TJ if you want to see what is involved with a raised belly skid.
  1. I see the Atlas is available with a 4:3:1 or a 5.0:1. Will the 5.0 be overly limiting when it comes to the time on the trail spent in between major obstacles where 4hi is too high and 4 low (with 5.0 ) is too low and slow?
3.8 or the 4.3 should be just fine for what you are doing. The 5.0 is better suited to the manual trans folks.
  1. I seem to run across more Atlas conversions than 241 conversions. Any idea why? I believe it is likely related to item #2.
I see them about evenly split with a lean towards more 241 due to the cheaper initial cost would be my guess. In days of yore, a 241 could be and was quite often acquired for sub 1000.
  1. I understand the swap will produce significantly more stress in the drive line. Given my setup (see above), what will likely be my new failure point?
Any corner that gets full delivery of the torque.
I am always trying to think ahead about the cascading effect of upgrades to my Jeep, but I sometimes miss the obvious. In your opinion, what am I missing? Why would I not want to do this?
The only reasons not to are motivation and expense. It is a worthy upgrade, (4-1) with an auto. If you ever get to the point where you remember my willingness to offer frequent guidance, it won't be a bother to walk you through either install.
 
Atlas is more effort. I forget what belly skid you have?
This is one of the more significant issues I will need to overcome. My custom-bent aluminum skid is tight to my raised transfer case, and I cannot bend 3/8 aluminum.

The 241 requires a digital speedo correction device. Atlas doesn't but we run one anyway.

This is probably the one thing working in my favor. I swapped an electronic pickup in my NP231 when I went to a JB Conversions Super Short SYE.

The floor plate where the t-case shifter is will need some work. We are currently installing an Atlas in a TJ if you want to see what is involved with a raised belly skid.

I am a fan of your clean work and am interested in seeing how you handle it.

The only reasons not to are motivation and expense. It is a worthy upgrade, (4-1) with an auto. If you ever get to the point where you remember my willingness to offer frequent guidance, it won't be a bother to walk you through either install.

I checked online prices for a used "roll the dice" 241, a rebuilt 241 without a core to return, and an Atlas. While the Atlas is more expensive than the other options, it is the direction I think I will head.

I appreciate your help and will undoubtedly have some questions.
 
This is one of the more significant issues I will need to overcome. My custom-bent aluminum skid is tight to my raised transfer case, and I cannot bend 3/8 aluminum.
If it is one of mine, then no need, that is the same one we use now. Just needs a crossmember to hold up the Atlas.
 
  • Like
Reactions: MikeE024
If it is one of mine, then no need, that is the same one we use now. Just needs a crossmember to hold up the Atlas.

Well, between that and the speedo, I am 90% of the way there. A couple more details and this thing will fall right into place. What could possibly go wrong?
 
The previous owner swapped an OEM 241 into my LJ and it works well. I would recommend it if the cost is significant between the 241 and the Atlas. I've never seen the need to go lower. Though I also don't know what I'm missing with doing front digs. If my 241 needed replacement, I'd consider an Atlas, but would still look for a 241 first.
 
The previous owner swapped an OEM 241 into my LJ and it works well. I would recommend it if the cost is significant between the 241 and the Atlas. I've never seen the need to go lower. Though I also don't know what I'm missing with doing front digs. If my 241 needed replacement, I'd consider an Atlas, but would still look for a 241 first.

3250 ish versus 1800-2400 for the 241 with high miles typically. Low mileage are hard to find.
 
  • Like
Reactions: suicideking
Over the weekend, I had the opportunity to experience the difference between my NP231 transfer case with a 2.72:1 ratio and a transfer case 4:1 in the rocks. I want to make a change but welcome the collective thoughts of this beehive of user knowledge.

A bit about my Jeep:

  • 1997 Sport 4.0
  • 32rh Transmission
  • Dana 30/Dana 44 that are locked and trussed with 30 spline chromoly axles. They are geared to 4:56.
  • Black magic 15” brake kit.
  • Custom belly-up skid.
My use case for my Jeep
  • What I do - My Jeep lives tucked into the garage corner. It comes out to explore the southern California mountains and desert. I run on everything from fire roads and mild trails to the Rubicon Trail, Moab, Johnson Valley, etc. I most enjoy the rocks. We love to drive it around town in the spring and summertime and don't want to decrease that pleasure significantly.
  • What I don't do - I do not intentionally take my Jeep in the mud. I actively avoid it and always will. I do not play in the dunes and have no desire to.

My random thoughts and questions that I have pieced together so far…
  1. I see two obvious ways to reach a 4:1 ratio: a 241 transfer case or an Atlas 2-speed. I am leaning towards the Atlas for the additional capabilities of a front dig in particular (and just because I can).
  2. However, I am unsure if one approach or another requires significantly more cost or effort.
  3. I see the Atlas is available with a 4:3:1 or a 5.0:1. Will the 5.0 be overly limiting when it comes to the time on the trail spent in between major obstacles where 4hi is too high and 4 low (with 5.0 ) is too low and slow?
  4. I seem to run across more Atlas conversions than 241 conversions. Any idea why? I believe it is likely related to item #2.
  5. I understand the swap will produce significantly more stress in the drive line. Given my setup (see above), what will likely be my new failure point?

I am always trying to think ahead about the cascading effect of upgrades to my Jeep, but I sometimes miss the obvious. In your opinion, what am I missing? Why would I not want to do this?

I put an Atlas 2 speed 5:1 in my '97 with an AX-15 and love it. I chose this route because the cost of a used 241 is too high for a used case, the ability to shift the axles independently, longer rear drive shaft by about 2.5", probably stronger, absolutely cooler. You should definitely have a discussion with @mrblaine, he's very gracious in sharing his knowledge. I have a fairly picture heavy installation detailed in my build thread starting here: https://wranglertjforum.com/threads/woodrows-97-green-tj-moderate-build.51602/post-1481482
 
Last edited:
  • Like
Reactions: Rickyd and MikeE024
3250 ish versus 1800-2400 for the 241 with high miles typically. Low mileage are hard to find.

If the cost is that close for a new Atlas vs. used OEM high miles, I'd probably do the Atlas if mine died. Figure the Atlas is going to be easier to repair later if needed.
 
I recently paid 1200 for a 241 out of a wrecked 30k mile TJR. I drove 6 hours roundtrip and it took me close to a year to find the right deal, but I consider myself lucky.

The swap from 231 to 241 is fairly straightforward, it took a noob like myself maybe half a day to complete, most of that was beating in the tub, swapping yokes and messing with the shifter. The Atlas swap not so much.


I can definitely see where a front dig is useful in an LJ on tight trails.
 
  • Like
Reactions: suicideking
I recently paid 1200 for a 241 out of a wrecked 30k mile TJR. I drove 6 hours roundtrip and it took me close to a year to find the right deal, but I consider myself lucky.

The swap from 231 to 241 is fairly straightforward, it took a noob like myself maybe half a day to complete, most of that was beating in the tub, swapping yokes and messing with the shifter. The Atlas swap not so much.


I can definitely see where a front dig is useful in an LJ on tight trails.

That's almost as good of a deal as what I paid for a TJ Unlimited hard top in good shape and the Dana 44 complete with discs out from under the same rig since I only spent 100 more for both of them.
 
That's almost as good of a deal as what I paid for a TJ Unlimited hard top in good shape and the Dana 44 complete with discs out from under the same rig since I only spent 100 more for both of them.

That’s a very good deal, regardless whether it was a front or rear 44.
 
  • Like
Reactions: MikeE024
I've done 3 241 conversions thus far and they have all been worth the money and effort. However, that was when prices and availability weren't a problem. Given those two things, going Atlas makes much more sense today. You'll pay more up front, in time and money, but it will be one less thing you have to worry about later.
 
If doing a GPS speedo, aren't there some years of JK Rubi cases that will work in TJ's?