Have any of you switched from the NP242 to the NP231? What is the input shaft spline count? I'm considering going to the 231 so I can install a TeraLow kit and get a 4:1 ratio.

Recently I computed the crawl ration of the KJ and it ain't pretty. Even if I upgraded to 4.11 gears, it's still below 40:1. Going with a TeraLow would almost double it.

Any notable differences between the 231 used in other Jeeps?

There's another option to consider for a better crawl ratio - a Rubicon. Something to keep your KJ company in the driveway. Just shake your money tree real hard.

_________________
05 BLACK KJ - 42RLE & NP242
Skids, Hooks, Bent Rock Rail, Lifted, A/T's, etc.
NY and PA and Florida ONF Special Custom Organic Trail Rash

If you can find one of those Rock-Trac t-cases that came stock on the Rubicions, they already have the 4:1, save you some time. Check ebay, your local junkyard, etc..


EDIT:
They are called NV241 or NP241

Here is an ebay listing:
Click here

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2002 Jeep KJ Sport 3.7L 4x4

245/75-16 Mastercraft Courser HSX, 16x7 Cragar, 2" OME MD Lift, ARB Bumper
AEM Brute Force Cold Air Intake, Flowmaster Super 44 Muffler

Currently working on: Full service on transmission & bed-lining ARB bumper

viewtopic.php?f=43&t=84650

The rocktrac transfer from the rubican's will bolt up to a KJ's tranny,you will need both driveshaft's remade though.Last I heard it is a perfect fit for the liberty and advance adapters does sell them,but why get one when you can get a atlas II transfer(the 4-speed version)and get the super low 10:1 reduction for about the same price and the atlas is lighter and stronger.10:1 low will really improve your crawl ratio.

Well, I'm thinking that I can pick up a NP231 for about $500 and a TeraLow for about $900, $1400 total. Atlas IIs start at a grand more than that.

Oh yeah, I'm shaking my money tree as hard as I can and I still can't afford a Rubicon.

Mutt...you will have to send your transfer case in to TerraFlex to have the conversion done. It takes them about 3 weeks to do.

_________________
Richard~Mid Atlantic VA Rep.
NCBBA/Mid Atlantic Jeepers/UFWDA Member
Mid-Atlantic & Carolina LOST #236236
2006 TJ Solar Yellow Rubicon
Lockers, Springs, Skids, Headers, Snorkel,
Exhaust Work, 4.5 Long Arm, Warn M8000
315/75/16 Nitto Terra Grapplers Moab's/SpiderTrax, 6000k HID, IPF H4

Rich,

Of all people, I should have known you have investigated this!

Aha!

http://www.lostjeeps.com/forum/phpBB3/vie ... light=trac

So maybe I can keep the 242.

Let me know if you need help with the swap. I have a guy here in Richmond that can ship the case off for ya. There website is here: http://www.independent4x.com/


Im not sure if the phone number is correct so let me know if it is not and I will find out the correct one for ya. Im very interested in seeing how this will work. I wonder if they change it to a twin shifter as well (Would be awsome!).

_________________
Richard~Mid Atlantic VA Rep.
NCBBA/Mid Atlantic Jeepers/UFWDA Member
Mid-Atlantic & Carolina LOST #236236
2006 TJ Solar Yellow Rubicon
Lockers, Springs, Skids, Headers, Snorkel,
Exhaust Work, 4.5 Long Arm, Warn M8000
315/75/16 Nitto Terra Grapplers Moab's/SpiderTrax, 6000k HID, IPF H4

the cawl ratio should be about the same as a TJ and mine aint too bad
i got 3.73 a 3 speed auto and 30" tires i am locked and if the bumper clears it i can climb it

as far as the tera low check out quadratec thay sell thekit for the 231 for around $1200 that would include a sye so a new rear d/s will be needed and a retube on the front but that will be very low and with gears that low mud will not be fun because you will not get the wheel speed to clean the tires imo

i would think that it would be better to go with lower gears in the axels 4.10 or 4.56
i know that every one says that you cant put 4.56's in but if a dana 30 trutrac fits and that is what the gears bolt to then i cant see why it wont?
most of the guys that i wheel with dont fool with the 4:1 t-case but in sted regear for the larger tires the general rule is some thing like this
30=3.73 nothing numericaly lower
31=3.73 will work ok for auto but 4.10 for 5 speed
32=4.10 for dirt trails ,if you have a 4 speed auto or a 5 speed and run a lot of rucks then maby 4.56
33=4.10 ok for auto 4.56 for 5 speed but some folks that wheel a lot of rocks will run 4.88

the way i see it is like this at 65mph i am cranking out 2800 rpm and grining all the way to the trail with the 4 speed auto i could probably run 4.10 and still turn less rpm at 65 heck i could probably run 4.56 and 31's if i had the trany that a KJ has so that beeing said i would go 4.56 if i were you

Your diff gear is only one aspect of the crawl ratio, the others being first gear in the transmission and low range in the transfer case. Being that the transmission first gear is only 2.84 and the transfer case low range is 2.72, it gives you a crawl ratio of 28:1. Going to the 4:1 low range T case would put the crawl ratio in the vicinity of 47:1 with 3.73 gears. So I could keep my highway mileage and still have great off road performance.

Going to 4.56s would still only give me a 35:1, but going to 4.56s and a 4:1 T case would give a 51:1 crawl ratio. Anything below 40:1 is less than optimal from my research.

Somehow I don't think you would need to go that low in a KJ unless you where going to do a SFA with 38" tires and turn it into a real crawler.

Sounds like fun figuring this all out but it seams overkill.

_________________
Ray's Renegade
L.O.S.T # RP052495
Light Khaki 2005 Renegade 4x4
28D package (full skids)
Trailer tow group
Auto tranny
Trac-Loc
Jeep seat covers
K&N air filter
Moog K3199 LBJs
Frankenlift
Al's upper A arms
Goodyear wrangler silent armor
255/70-16

Sorry to say but 4.10's is the lowest you can go in the KJ's dana 30a until someone makes special ones.The pinion shaft is longer on the dana 30a so the ring gear for any dana 30 will work just the pinion will be to short .