NP249, NV249 Transfer Case swap to NP242 or NP231
Before we get to ahead of ourselves on the swap, let’s 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 you’re doing more extreme 4X4ing, isn’t 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 can’t 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(that’s 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 it’s 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 don’t 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. Don’t 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 it’s 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 it’s 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.
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Credit for this article to B.C. Jeep Club
Before we get to ahead of ourselves on the swap, let’s 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 you’re doing more extreme 4X4ing, isn’t 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 can’t 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(that’s 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 it’s 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 don’t 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. Don’t 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 it’s 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 it’s 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
mine would be mostly used for daily driving with occasional trails
