Does anyone know of a kit to swap out to lower gears in the T-case when in 4wd? Even with an automatic i think it would be benificial to have lower gearing much like the doublers that are added to the standard trans rigs. Thanks.

 

There is 4:1 low range conversions for the np231, factory low range is 2.72:1

 

Doesn't that kit have problems if run above a certain rpm ??

 

That's the first I have heard of that but I haven't looked into it that much. The factory low range is good enough for what I need it for.

 

Some wranglers with the same t case had problems with that kit blowing apart.I would save up a little more and get a atlas 2 t case.Its more money but its almost bolt in,But its pretty much bullet proof and the twin stick is nice in tight spots.

 

Some problems with that kit https://wranglertjforum.com/threads/...fer-case.4802/

 

You can swap in a Rubicon transfer case from a TJ. That'll give you a 4:1 low. The JK transfer cases don't have a speed sensor so they're difficult to use in an XJ.

For more money you can buy an Atlas transfer case. They have several options for exactly what low range ratio you can go with from 2.0:1 down to like 5:1 or 6:1 or something like that. It also gives you the ability to do 2wd low in either FWD or RWD.

You can also get a 4 speed Atlas. It's basically a regular Atlas but it has an extra reduction box on the front of it. That can give you all the way up to 11.7:1 low range along with 2.72:1 and 4.3:1. So you have plenty of coverage for all situations.

 

Terraflex makes a 4 to 1 conversion kit for the 231 transfer case. It is around $1300,

 

Not any more.

 

Good to know that terraflex has discontinued it.

 

And you can run a doubler on any trans as long as you get the parts to make one.

 

It was a crappy setup and never should have been sold. They were in over their heads with it.

If you just want 4:1 and the closest thing to a factory install possible, go with the Rubicon case. If you want 4:1 and want it to last, but don't mind spending, buy an Atlas. If you want 4:1 and want it to last, but are cheap, and don't mind the weight and packaging penalty, the NP203/205 setup is an option. If you want 5.33:1 and 2.72:1 and don't want to spend a fortune, a NWF Ecobox and a Ford NP205 is the way to go (what I have). If you want multiple gears and ratios, and are willing to spend, the 4spd Atlas is a good choice. If you're breaking Atlas stuff, it's onto the Hero or a NWF Titan.

 

and if yer gonna use a 205, go with the lomax gear kit to make the 205 3-1.

 

I don't want to come off totally rude, but no, don't do that, it's a retarded idea. Firstly, I don't think they intend to make any more of them, as they're not a great choice from the economic perspective and had sold poorly since the time the Atlas became mainstream. They were last priced at about $1600, and I don't think they had much profit margin at that point, given how complicated of a casting the main case is, and the amount of machining needed to finish it AND the gears. Cost wise, at $1600 you still needed a good tcase to donate the shift forks/rails, idler shaft, and the tail/front output housings along with a bunch of other small parts; this stuff could be purchased new but would be very expensive. You also needed a bearing/rebuild kit (reusing the bearings from the donor case isn't terribly feasible, or a good idea) at about $250. To be conservative you'll be into it at least $2000, and probably have the wrong yokes and need to purchase a doubler or pricey adapter to use it; an Atlas can be had rather bare for about $2200 if you know who to call. Also, they only ever patterned a GM case, as the fullsize GM guys were the target market of the it when it was developed. Since it is patterned on a GM case, you need to run it passenger drop, or flip it. If you flip it, it will leak. The only inputs available are GM 10, 27 and 32 spline, so unless you run it behind a doubler like a Blackbox/Ecobox or buy a rather expensive adapter you can't adapt it to a Jeep tranny; again this is because it was marketed to GM guys.

I have an Ecobox/NP205. It is hands down the cheapest way to get deep reduction and not be worried about failures, unless you happen to stumble across a used Atlas for nothing. As another bonus it gives me 3 gears, as I don't want too low of a low range for snow wheeling.

 

I did the np203/np205 doubler with the lomax 3-1 gears in the 205 using my dodge 203 & 205.

My total cost per my receipt was:
$1095 Lomax 3-1 kit for the 205
$169 NP205 rebuild kit
$99 Range box rebuild (203)
$699 NP203-NP205 adapter plate/kit
$265 Triple shifters

Total cost was $2327.

or about 60% of what an Atlas was when I priced it all out (apparently I didn't know who to call).

This gave me 1-1, 2-1, 3-1, & 6-1 reduction from the tcases.

But anyway, I don't care, just suggesting options that are available for the 205 gearing.

For me, I went this way because it was all cast iron (strong) as it was going to reside behind 750 hp, and it saved me money too over the other options available at the time.



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