From Mechanical Database
The following describes a simple breakdown of the NV242 transfer case while it's still installed in a Jeep. The following was performed to quickly eliminate a bad leak. Therefore having to drop the whole case was unnecessary. This experience can prove beneficial when doing further upgrades such as the Slip Yoke Eliminator kit. For now though, we're just gonna fix a leak.
This article consists of the following parts:
- Listing of the tools needed and what they will be used for and the breakdown of the case.
- Clean up & reassembly of the case.
- Technical view of the 242 t-case and the differences between them. Somewhere between late 1990's and early 2000's, New Process changed it's name to New Venture. Therefore you will find that there is an NP242 and the NV242. My 242 has the New Process tag but it's designed like the NV242.
Please, please, please read this write-up before you tear into your case. Even though this is the NV242 out of my '98 ZJ, the basics of this breakdown applies to almost any t-case. Of course there will be differences.
Let me explain to you about the types of pliers used here. When I say Heavy Duty, I mean don't go cheap on these. The pics below have an insert that will show you the type of rings that the pliers will be used for. The pliers on the Left are Internal & Extermanl Retaining-Ring/Snap-Ring Pliers. The pliers on the right are Lock-Ring Pliers.
The next task to be done will be choking/blocking all four wheels. Even if the trans on your Jeep is in park, once you start messing with the t-case, your Jeep could become effected and roll away while you are underneath. I placed my Jeep in park but kept the t-case in neutral so I could rotate the rear driveshaft as I was taking it off. Keeping the t-case in neutral also helped out a bit when it came time to remove the lock-rings.
On the tools list I mentioned jack stands. This is for those who have small or no lift at all. My overall suggestion is this, if you have no problems getting underneath your Jeep then stands may not be necessary. Keep in mind that for this task we are not dropping the t-case but you will still need plenty of room to move around underneath.
Once you are certain that your Jeep will not roll away it's time to crawl underneath and drain your t-case of fluid. You will see 2 plugs, unscrew the drain plug with a 10mm Hex Key.
Next use either needle nose or regular pliers and remove one of the two metal bands securing the Slip Yoke rubber boot, which is located on the slipyoke portion of the driveshaft. The strap to be removed secures the boot to the transfer case slinger.
You will find that this strap is a pain in the ass to remove. If you feel that it can not be reused, fear not as zip ties will make an easy replacement. If you use zip ties, you must be careful in removing them so that you do not damage the boot next time you do this project.
Move to the rear of the axle and remove 4 bolts and 2 yoke straps that secure the drive shaft to the rear axle using a 5/16" socket or wrench. This is where having the t-case in neutral helps. Once you have the 1st yoke strap removed you can grab the driveshaft and rotate untill you remove the 2nd strap. Be prepared to catch the ass-end of the driveshaft in case it drops to the ground. If it does not drop, don't worry as you are about to learn why the other end is called a Slip Yoke.
Simply grab the driveshaft and slide it forward as if you were trying to shove it into the transmission. The ass-end should disengage itself from the axle. You will notice that the driveshaft is rather light. Now slide the shaft out of the transfer case and place it out the way. What you should see is this.
Unplug the speedometer wiring harness connected to your transfer case tail housing. Here you will need to use a small screw driver to slide out the red key locking the connector in place. Disconnect the plug from the speedometer gear.
Using a 1/2" socket, remove the retaining bolt and metal clip securing your speedometer gear housing to the tail housing.
Firmly grab the speedometer gear housing and carefully pull it out. If you have bigger tires already, now would actually be a good time to change this gear out to correct your speedometer. Remember the original orientation of the speedo gear during reassembly!
Here is where the fun really begins. The removal of the slinger was an ass kicker for me. There are several ways to remove this. You can use a gear puller with a 5" reach to extract. This can be rented from your local autoshop.
Or use a chisel / flathead screwdriver & hammer. I ended up making a slight groove for the flathead to grab onto and hammered the slinger loose. It rotated counter clockwise off.
Now that you have that P.O.S. off, there will be a metal slip-ring (if you have one). Simply slide it off and you should see your 1st lock-ring and the Output Shaft Seal.
Grab your lock-ring pliers and go after the lock-ring holding the Output Shaft Seal. If you plan on re-using the lock-ring, be careful not to damage it. It is possible to bend & warp the ring.
Remove the Output Shaft Seal by tapping a flathead screwdriver with a hammer all the way around the seal until it comes off.
Remove the 2nd lock-ring that keeps the Output Shaft Bearing in place.
Remove the snap-ring that holds the tail Housing in place.
Remove all bolts holding the transfer case tail housing using a 15mm socket.
After all bolts are loose, you should be able to whack the tail housing with a rubber mallet. If you end up having to use a screwdriver & a hammer be careful not to damage the case as it is made of aluminum.
Grab the tail housing and slide it off the Output Shaft.
Here is where you should be. What you are looking at is the oil pump.
Look carefully at the teeth deep inside the output shaft and the teeth on the speed gear and see how they meet to measure the speed of the Jeep.
Now it's time to break open the t-case. Using a 15mm socket you will remove all bolts except for one at the top. For the top bolt you need a 10mm 12-point socket. Pay attention to where each bolt came off and arrange them accordingly on the ground. You will notice that a couple of them are longer and that 2 of the bolts have washers. All bolts will need to go back to the specific hole they originally came from.
Here is a look at the bolts. Notice the 12-point bolt on the right. The other two bolts are the same except that one has a washer & is slightly longer.
The 12-point bolt gave me one hell of a hard time. I ended up having to reach around the back end of the transfer case only to realize that I had forgotten there is a nut back there that is used to hold a wire retainer. Not only did I have to unthread the 12-point bolt from the t-case itself but also from this nut thus making life rather hard. This nut is not required for reassembly. Just make sure you keep the wires out of way.
Here is the order in which the bolts are placed. Notice the two bolts on the far left & right with washers & the 12-point bolt.
Look at the seam of the t-case and you find a small notch where a flat head screwdriver can be placed. Carefully pry open the t-case without using excessive force which can cause damage. Watch out as more fluid will pour out.
With the transfer case partially separated, you should be able to remove the oil pump by lifting up and pulling it off the output shaft. There is a small oil pickup tube at the base of the pump that will need to be disconnected. It's just held in by a rubber O-ring and will unplug with little effort.
Remove the t-case half and set it aside. At the base of the t-case, you will find a flat round magnet in a slot where the two halves come together.
This is a collecting magnet used to grab metal shavings. It will look rather fuzzy at first but truth be told, that's metal shavings. Pull this magnet out and clean off all metal fillings attached to it. Look for larger chunks that would indicate serious wear or damage to the components inside the case. In the photo below you will see the shavings left behind after a slight cleaning. I used lots of brake cleaner & rags.
At this point, the break down is complete.
A gasket scraper & brake cleaner, or degreaser of your choice will help out a lot. Once again be careful not to damage the case itself. Be sure not to allow any of the old gasket residue to fall inside the case.
Clean up the tail housing as well.
It may not be possible to get it all 100% clean but make enough of an effort to ensure that the new sealant will stick.
Once you have everything cleaned off, it is time to get out some RTV Gasket maker and have at it.
Using a 1/16" to 1/4" bead of RTV, make a continuous even bead of silicone to one surface surrounding all bolt holes.
Let the silicone dry for a bit then assemble the 2 halves. Finger tighten all bolts (or lightly use your socket) until the silicone begins to squeeze out a bit all around. Allow the silicone to dry for 1 hour then retighten 1/4 to 1/2 turn.
Insert the oil pump. This is a bit of a tricky install because the oil pickup tube MUST be inserted into the oil pump.
Just use a small flathead screwdriver to do this.
Here is a bit of backwards orientation. This photo will give you an idea what you are trying to accomplish.
Using a 1/16" to 1/4" bead of RTV, make a continuous even bead of silicone to one surface surrounding all bolt holes for the tail housing.
Once again allow the silicone to dry for a bit then carefully slide the tail housing over the output shaft. Finger tighten all bolts (or lightly use your socket) until the silicone begins to squeeze out a bit all around. Allow the silicone to dry for 1 hour then retighten 1/4 to 1/2 turn.
Once the RTV has dried, tighten every bolt down and insert the snap-ring onto the tail housing.
Insert one of the 2 lock-rings onto the output shaft. Pay close attention this part. The lock-ring will slide into a groove on the output shaft right up to the output shaft bearing. Make sure it snaps in the groove.
Insert the output shaft seal. This might be a bit tricky though, if you look at the backside if this seal you will see a thin round retaining spring. This spring will make inserting the seal a bit of a pain in the ass.
The rubber mallet will come in handy for this task.
Insert the last lock-ring. This lock ring will also slide into a groove on the output shaft right up against the output shaft seal. Becareful not to damage the seal!
If you have a slip-ring, insert it on top of the lock ring.
Insert the slinger.
Re-assemble the speed gear. Remeber the original orientation of the speedo gear during reassembly!
Now you should be at this point. Granted there is a ton of RTV that can be seen. I'm not out to win any showroom trophies but if having some extra silicone bothers you, then by all means trim it off.
Check your service manual and fill the t-case up with AT+3 or AT+4 of your choice and watch for leaks. If there are none, then resume the assembly by putting your driveshaft back on to the t-case in the reverse order that you took it off.
Please keep in mind that is only a basic break down & re-assembly of the 242 that came with my ZJ. Its a 98 with well over 134,000 miles at this time of this write-up. I know there are many other versions of the 242 as mentioned earlier. Hopefully with this knowledge, you will be able to do this and eventually move on to bigger projects like installing a Slip Yoke Eliminator kit.
Disassembly & reassembly of many transfer cases are the same however. You may find that the bolt on your case may have 10mm all the way around rather than 15mm like mine. Just pay close attention to what you are doing at all times. Make notes of where everything goes, take your time and all will go smoothly.
An earlier version of the 242, the NP242 (New Process) has a 3 bolt extension housing that attaches to the tail housing / rear retainer similar to the NP231. Plus you have a 249-242 hybrid t-case.
This is the NP242 that has the 3 bolt extension housing (#14) that bolts up to the tail housing / rear bearing retainer (#13). This model is offered on 93 to 95 ZJ's.
- Shift Lever.
- Sector O Ring
- Shift Lever Retaining Ring
- Outer Shift/Mode Fork Pads
- Center Shift Fork Pad
- Center Mode Fork Pad
- Range Shift Fork
- Mode Shift Fork
- Front Retainer Seal
- Front Bearing Retainer
- Input Gear Bearing
- Input Pilot Bearing (input gear / mainshaft)
- Rear Bearing Retainer (a.k.a. Tail Housing)
- Extension Housing
- Output Shaft Seal
- Indicator / Vacuum Switch Seal (speedo gear)
- Front Yoke Nut
- Front Yoke Seal
- Front Yoke (also pictured are the slinger & oil seal)
- Front Output Shaft Rear Bearing (with lockring)
- Drive Chain
- Mainshaft Bearing Rollers
- Differential Sprocket (pictured is the whole differential assembly)
- Input Gear
- Oil Pump Tube O-Ring
- Oil Pump Pickup Tube Screen
- Low Range Gear
- Shift Sleeve
- Oil Pump Seal
- Rear Bearing (with snap ring)
- Oil Pump
- Rear Case Half
The photo below is the NV242 (New Venture) that I currently have under my '98 ZJ. This is the newer 242 that is bolted on 96 to 98 ZJ's and is also featured on WJ's & KJ's.
However, there are models like this that will have the New Process tag! Just look for the tail housing / rear bearing retainer (#11), slinger (#31), and the slip yoke boot (#37).
- Front case
- Drain / Fill Plugs
- Detent Pin
- Seal Plug
- Detent Pin Spring
- Detent Plug
- Rear Bearing Retainder (a.k.a. Tail Housing)
- Goo in a Tube?
- Vent Tube Assembly
- Spacer (there are 2 for this half of the case)
- Washer (there are 2 for this half of the case)
- Bolt (used for the spacer & washer listed above)
- Retainer (used with the 12-point head bolt that holds wiring out of the way)
- Indicator / Vacuum Switch (speedo gear assembly)
- Indicator / Vacuum Switch Seal
- Vent Tube Assembly
- Vent Tube Assembly
- Vent Tube Assembly
- Rear Case
- Oil Pump Tube O-Ring
- Oil Pickup Tube
- Oil Tube Pickup Connector
- Transfer Case Oil Filter (screen)
- 12-Point Head Bolt
- Transfer Case Flange Slinger (also pictured is a slip-ring if equipt)
- Output Shaft Bearing
- Reatining Ring (snap-ring)
- Output Shaft Seal
- Slip Yoke Boot Front Clamp
- Slip Yoke Boot Rear Clamp
- Slip Yoke Boot
The majority of the photos used here are by zj-monster with the exception of a few. Those photos are courtesy of Eddie at 4x4xplor.com and came in handy when a few weren't taken during the process.