NP249, NV249 Transfer Case swap to NP242 or NP231


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Old 03-27-2009, 07:16 PM   #1
WJCraig
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Default NP249, NV249 Transfer Case swap to NP242 or NP231

NP249, NV249 Transfer Case swap to NP242 or NP231

Before we get to ahead of ourselves on the swap, letís discuss why you would want to swap. The NP249 is a strong Transfer Case (TC), but its weak point is the Viscous Coupling (VC). It will always eventually fail no matter how well you maintain it. when it is working fine, it only engages to 4WD when it feels slip in the rear wheels, which if youíre doing more extreme 4X4ing, isnít good, you want grip on as many tires as possible before slipping even occurs. So the obvious decision then is to swap in a TC that allows that.

The NP 231 is a good choice, which has 3 setting, 2WD, 4WD, and Neutral, with some modification, you can add 4WD Low
the NP 242 is a better choice which has 5 settings. 2WD, 4WD full time, 4WD part time, Neutral, and 4WD Low, making it the perfect TC for a dual purpose rig.

To find a donor, you can either go buy a new one, or a used one from the wreckers. If you doing the NP242, you can find it in more commonly in the 1980's Cherokee, or less common in 1993 Grand Cherokee, as it was only sold as an option. The easiest way of telling if the vehicle has one, is by looking at the shifter bezel. If you see all 5 settings, your good, but if you canít see the bezel, you will have to get under the Jeep and look for the ID tag on the TC.(see Image1 below)

Tools and Supplies Required
-Snap-ring pliers (good quality will make a difference)
-Socket set
-Screwdriver set
-Hammer
-Wrenches
-RTV and Transmission fluid
-Rags
-Wheel chocks
-Jack

Lets Proceed into the swapping
- Allow 2 days to do this job, it is possible to do in 1 day if everything goes perfectly
-Clean up donor TC and made sure it goes smoothly into all the gears, if not you will need to replace them while you have it apart(thatís a whole other tutorial)

Removal and dismantle of the 249 TC
-Chock your wheels
-Drop your skid plate if you have one
-Remove rear drive shaft
-Put a jack under the transmission(behind pan) to lower it a bit after removing the cross member(2 bolts on each side, and 1 in the middle in the transmission mount).
-Remove the case from the jeep (6 X 15mm bolts hold it on)
-Drain the case, then removes it from the jeep.
-Drain it some more when it's off, it'll bleed ATF from every orifice.
-Remove cover on the tail shaft. (See image 2 & 3)
-Remove the few snap rings under that cover.
-Remove plate on the tail shaft.
-Remove the speed-O sensor that is right next to the tail shaft.
-Loosen all the screws on the cover and break it loose. Use a hammer and screwdriver as itís RTV'd.
-Grab the snap ring and slide it off as you slide the cover off.
-Take out the bolts in the center of the case and break it open. (See image 4 for open case)
-On the left side behind the shifter that you see slid down, is the sun gear you need. You will need to tap the input slightly to get it out.(see image 5 to see what it looks like out of the case, you donít need to remove it from the planetary gears it was done for a better image)

Dismantle of the 242, and reassemble with 249 parts
-Make sure you do this on a clean surface!
-Proceed to take the 242 apart following the directions of the 249 (they are very much the same) make sure you pay close attention to how you are doing it. The innards of the 242 and 249 are very similar.
-Remove the shift linkage to the top position to prepare to remove the shift forks.
-Remove the pin on the shift fork that hooks to the swing linkage on the inside of the case. Use a pry bar and wedge it in between them. Use just enough pressure to pop the shift fork pin out and slide it up. When this is done, shift the T-case again, and the lower shift fork will pop out and the sun gear will come out at the same time. Donít forget to take the front cover off and remove the snap ring first.
-Install the sun gear out of your 249 onto the 242 with gentle tapping; Make sure itís fully seated. (See picture 6 to see 249 inputs on the 242)
-On reassembly use RTV.
-Install your new T-case and put the selector in 2WD and switch the T-case into 2 wheel drive.
-Adjust the slide nut on your linkage so that you can hook the linkage up.
-If the donor T-Case is from a '93 or newer, you can just plug the shift indicator in. If itís not, then you will need to buy the part from Jeep.
-The speedometer sensor is another concern in a pre '93 T-case. Your sensor out of your 249 will work and obviously will plug in.
-On the inside of the truck remove the radio bezel (6 Philips screws) and pop it out.
-Pull out the Vehicle Info center (3 Phillips screws) and you will see two sets of plugs, a red one and a black one.
- Whichever plugs are hooked up, unhook them and hook up the others on the new TC


this tutorial is a compilation of a few I have seen on the net. Both made sense, but missed some key parts.












Credit for this article to B.C. Jeep Club


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Old 03-28-2009, 06:43 AM   #2
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Thanks Craig!!!! The seemingly last correctly working NV249 is starting to fail... so I get to do this job now..

BTW... you should note that when in 4low the 249 performs just like a normal T-case. Its locks into 4wd and the VC is along for the ride.
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Old 03-30-2009, 02:45 AM   #3
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You know if you have it apart, the Chevy version of the 231 has a planetary with six outside gears which adds greatly to its strength...
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Old 03-30-2009, 03:58 PM   #4
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Correction RE: 231 it has 4 settings 2wd 4hi N 4lo. It is a "part-time" 4wd in that it is ment to be run in 4hi and 4lo in slippery situations only. It is the strongest of the group 231, 242, 249, but the 242 is the most flexable as it gives you the option of fulltime 4wd. 242 gives the offroad capability of the 231 and the on road AWD funtion of the 249 without the drawback of the VC.
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Old 04-05-2009, 03:33 PM   #5
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Is the 231 a direct swap onto a 96 limited with the 5.2 ?
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Old 06-30-2009, 05:18 AM   #6
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Quote:
Originally Posted by 93gc40 View Post
Correction RE: 231 it has 4 settings 2wd 4hi N 4lo. It is a "part-time" 4wd in that it is ment to be run in 4hi and 4lo in slippery situations only. It is the strongest of the group 231, 242, 249, but the 242 is the most flexable as it gives you the option of fulltime 4wd. 242 gives the offroad capability of the 231 and the on road AWD funtion of the 249 without the drawback of the VC.
Question is the case of the 231 and the 242 or 249 the same. I need to put the rear part of the cse on a 242 as it is broken and I can see the chain... the T-case works great but I would like to fix it as I can not see it being a good thing that you can see the chain. LOL
thought I would ask you as you seem to know your why around them...
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Old 11-09-2009, 01:16 PM   #7
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what is the settings on a 249?
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Old 12-06-2009, 11:18 PM   #8
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i have the 93 zj with the 242, so this has no vc? i dont think it was a option on the early model year laredo 4.0s i think it was standard...all i know is i have 4hi fulltime and partime hi and low and i love it. ive wondered about the np249j since its all i see behind the 5.2l zjs. whats the other tc used on the 4.0 zjs? and whats the weak points of a np242?
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Old 01-19-2010, 03:22 PM   #9
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Default Transfer Case

I have a 98 grand cherokee tsi. i have a np249 my 4 low is workin fine, but my 4 all time is not sending torque to the front axle. i am drivin in 2wd because is not engaging the 4 all time. i bought this new transfer case about a year ago and is not 4wd in 4 all time.

What could be the problem?
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Old 11-30-2011, 10:36 AM   #10
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Default 1993 Jeep Grand Cherokee Limited

ok guys.. I have a question. What kind of transfer case should I have in my jeep right now? I have a 1993 Jeep Grand Cherokee Limited 5.2 V8 with the 4hi Neurtral 4lo. options. I need to replace it and would like to try and do it my self. Is there a suggested replacement and can i upgrade to a transfer case that allows me to go into 2hi also?
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Old 12-01-2011, 04:56 AM   #11
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If that is the only three settings you have... then you have the NP249. In 1993, you could have had any of the three transfer cases.
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Old 12-18-2011, 03:19 PM   #12
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looking at doing this swap is it better in doing the np241 or the np231 im kinda confused about this? mine would be mostly used for daily driving with occasional trails
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Old 12-18-2011, 03:20 PM   #13
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which parts from the np249 get switched to the other transfer cases?
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Old 01-06-2012, 11:17 PM   #14
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Default tcase swap

Thanks for all the great info guys,
I have a 1995 GC i looks like the trans has been changed to a 1998 and the TC is still and 1995 249. I was wondering if a 242 case out of a 1998 would have to have the input shaft changed as or if it would be a straight bolts up. Note it has a 4.0 engine if it makes a difference.
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Old 10-07-2012, 09:46 PM   #15
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If I found a 231 or a 242 from a 96 the same year as my zj would I need to change the input shafts from the 249 to the other case?


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