How to rebuild 241 or 241OR transfer case

M

motomick76

Guest
Rebuilding NP241 or 241OR Transfer Case

Pre-work:


I have had some noise from what I thought was my rear axle, but actually was coming form my x-fer case. I posted a thread here on the issue. After running the Jeep on stands, there was alot of noise from the case. Not what I really wanted to do, but had to be done. I ordered a bearing and seal kit from Allstate Gear - NP241J. Here I will break down the process of overhauling a 241 x-fer case.

Any questions not answered here you can refer to the FSM found here: Jeep FSM Manuals

Items Needed:
  1. NP241 Bearing Kit - Allstate Gear
  2. Mopar ATF +4 Fluid - 2 Quarts
  3. Permatex Anaerobic Gasket Maker #51813
  4. 32mm Deep Impact Socket
  5. Snap Ring Pliers
  6. 10mm, 13mm socket and ratchet
  7. 10mm Allen wrench or socket
  8. 3/8" and 1/2" torque wrench
Before starting the teardown, it is a good time to take inventory of the bearing kit. In the kit there should be:
  1. Two 6207 bearings
  2. One BD-50-8 bearing
  3. One SCE2416 needle bearing
  4. One SCE2110 needle bearing
  5. Two F4284 seals
  6. One T-10 seal
  7. One thrust washer
  8. One C-572 seal
  9. Misc. washers and O-rings
pxl_20201108_220950660-jpg.jpg



Disassembly:

Once the case is out and on the bench, time to drain the oil. Remove the lower plug at rear of case, it is a 10mm allen. When I removed mine, hardly any oil cam out?! At one time i thought I checked it, but I digress.

pxl_20201029_155759630-jpg.jpg



Next come off the yokes. You will need a deep, thin wall 32mm to get the nuts off. The yokes should slide right off with the nuts removed.

pxl_20201029_174812661-jpg.jpg


pxl_20201029_175449631-jpg.jpg


I then started removing all of the 10mm bolts. I started with the rear flange cover and seal. Then I removed the 18 from the case halves. There is one 13mm on the top of the case. Take note of where it came from. The rear flange seal is pretty easy to get off, there are three tabs, just slowly pry with a screwdriver, and should pop off.


pxl_20201029_181258115-jpg.jpg


pxl_20201029_181301053-jpg.jpg


pxl_20201029_175016602-jpg.jpg


With the 18 bolts removed it is time to split the cases. Take your time and try not to damage the machined case halves getting them apart. The rear case half should slide away from the front case half half. In the rear case should also be the oil pump. DO NOT remove the bolts for the oil pump. This pump is aligned at the factory to the bearing race, and any movement will change alignment, rendering it useless.

This is how your case should look when removing the rear cover. (I forgot to take pictures, this is a reassembly picture) Remove the spring for the mode selector and set it to the side. Take a close look in the lower left of the case and note where the magnet is. It could be in either side of the case. Remove it from the case and set it aside. The front and rear sprocket assembly should be ready to pull out. Lift both sprockets out evenly from the case. They are heavy. Once lifted out the sprockets and chain can be separated. Also note when lifting out the sprocket, the mode fork will also come out. Try not to drop it and not loose any of nylon shims in the fork.

pxl_20201110_161619156-jpg.jpg


Here is what your sprocket assembly should look like when removed. Also is the mode fork in its position. There is no bearings or seals in this assembly, so all that is needed is a visual inspection of the mode fork and the three nylon bushings.

pxl_20201110_155931821-jpg.jpg


When I lifted out the sprocket assembly, I was greeted with a burned range fork. I did get this case used, and suspect that this happened with the previous owner. There were several flags I suspect this -
  1. It was split to install a Teraflex 2 - low kit. They used black RTV instead of an anaerobic sealant for the case. If you look at the rear seal cover shows all of the excess RTV on the inside. I am assuming that it could have blocked the drain back somewhat.
  2. There was more excess sealant on the split cases. The screen for the oil pump was half blocked, the magnet was covered also. If they were this careless, I am sure they were careless about the adjustment of their shifter upon re-installation, hence the burned range fork.
pxl_20201029_233708870-jpg.jpg


pxl_20201029_233721297-jpg.jpg


At this point you can remove the fork rod and flop the case around with the front facing you. Time to remove the remaining 12, 10mm bolts for the front side of the case to remove the planetary assembly.

When removing the assembly be careful as the ring gear may also slide out with the planetary set. If you have not done so already, remove the range gear from the planetary assembly.

pxl_20201108_232533653-jpg.jpg


This is the planetary flipped upside down and the ring gear is still on the planetary set. Also the range gear is resting in the planetary set.

pxl_20201108_233241475-jpg.jpg


The Planetary set is held in with a snap ring under the front seal. Dig out the seal on the input shaft, and there is a snap ring behind it. You will need a set of inside snap ring pliers to get the snap ring out. Pair I used is below which I got at O'reillys. With the snap ring out, the planetary should slid out from the bearing housing. On inside is the input bearing held in by a snap ring. The planetary is heavy, set it aside.

pxl_20201030_025018848-jpg.jpg


pxl_20201108_222556453-jpg.jpg


Below on the face of the planetary is a thrust washer. Remove old washer and install new thrust washer.

pxl_20201108_222608214-jpg.jpg


Rebuilding:

With the bearing housing upside down allows access to the input bearing. There is a snap ring holding the bearing in. Compress the snap ring and the bearing should slide out. Insert new BD-50-8 bearing along with snap ring. Seat bearing until snap ring expands in grove.

pxl_20201108_222545168-jpg.jpg


pxl_20201108_221006799-jpg.jpg


With new bearing installed it is time to reinstall the planetary set. Install planetary set and install snap ring to hold set into housing. Install the input seal, marked T-10. Carefully drive seal in evenly until flush with housing.

It is time to replace the output bearing for front driveshaft. With the main front housing on bench, remove the old seal from front output and using a socket and hammer, tap out the old bearing. Install the new #6207 bearing and drive in a new F4282 seal.

The rear housing has two bearings, a output bearing and a needle bearing set for the front output. The rear output replacement is the same as the front. Carefully drive out the old bearing, and side a new #6207 bearing in. The needle bearing is in a dead end, so it will take some creativity on your part to get it out. I first removed the inner cage and bearings, laving only the outer race. I then cut notches in the race to fit some washers inside to 'grab' the race and pull the bearing out. I setup a puller shown below to get the bearing out. Once out, I drove the new SCE 2416 needle bearing in.

pxl_20201108_220442832-jpg.jpg


New needle bearing:

pxl_20201108_221014823-jpg.jpg


There is just one seal left to remove and install, and that is on the rear output cover. Remove old seal and drive in the last F4284 seal.
 
Last edited by a moderator:
  • Like
Reactions: psrivats
Rebuilding 241 or 241OR Continued

Reassembly:


Now all of the seals and bearings are installed and replaced, it is time to reassemble the transfer case.

Start by having the planetary set facing down, slide the ring gear into the planetary gears. This is going to take some finesse, so take your time. It should easily slide over the four gears.

Place a small bead of anaerobic sealant on the mating surface of the planetary cover. Do not use an excessive amount, as the extra will end up inside the case. No wider than 3/16" bead. Slide front transfer case half on the planetary assembly. To get cover to fully seat, the square tabs on the ring gear slide into tabs on the case. When seated in place, carefully flip the case and front planetary assembly. Install the 12 - 8mm bolts and torque to 15-20 ft-lb. When bolts are torqued, flip case around again so input shaft is resting on the bench.

Install the range gear into the planetary assembly. Slide the range fork and slide rod into the transfer case. The range fork needs to slide in the range gear and also the fork pin needs to slide into the range selector. The selector may need to be rotated to get assembly to fit together. Be sure the nylon bumpers on the fork stay in place and are fully seated.

pxl_20201110_155900419-jpg.jpg



pxl_20201110_155919792-jpg.jpg



Assemble the chain, front and rear drive sprockets on the bench. Slide mode fork into the mode gear and slide assembly into the transfer case. The mode fork must slide on to shaft first, then the front and rear sprocket assembly's will side in. Rotate front and rear sprockets to get all components to side into place. Ensure mode fork stays engaged to mode gear and ensure three nylon bumpers in fork are seated properly. Verify mode selector pin is seated properly into selector.

pxl_20201110_155931821-jpg.jpg



pxl_20201110_160011754-jpg.jpg



pxl_20201110_160120907-jpg.jpg



pxl_20201110_160350709-jpg.jpg



pxl_20201110_160347121-jpg.jpg



Insert spring on range/mode shaft. Clean magnet and slide into case.

pxl_20201110_160445492-jpg.jpg



pxl_20201110_161052147-jpg.jpg



Apply another bead of anaerobic sealant on the case mating surface. Remember, not a bead larger than 3/16" is needed.

pxl_20201110_161619156-jpg.jpg



Align oil pump with main shaft and align shift rail with bore in rear case. Then install rear case onto the front case. Be sure oil pickup tube is in the correct position during assembly. Verify that shift rail, and case alignment dowels (3) are seated before installing any bolts. Case could be cracked if shaft rail or dowels are misaligned. Install 8mm bolts and the odd bolt into case. Carefully hand tighten all bolts. When case halves are fully mated and bolts hand tight, torque bolts to 15-20 ft-lbs.

Rear seal cover now needs to be installed. There is only one position this can be installed, as there is an oil drain back for the seal and bearing, and these must be properly aligned. Apply another bead of anaerobic sealant to mating surface of cover, and install. Take note of pictures on proper alignment of cover.

Oil drain back on transfer case -

pxl_20201110_162424013-jpg.jpg



Oil drain back on cover -

pxl_20201110_162431573-jpg.jpg



With cover on, install remaining 6 - 8mm bolts and torque to 15-20 ft-lbs.

Install front and rear yokes. Torque yoke bolts to 90-130 ft-lbs.

pxl_20201110_171729804-jpg.jpg



Before filling with oil, verify operation of case by spinning input shaft and selecting through the ranges and modes. It should shift easily and smooth. If all modes and ranges work properly, it is time to fill it with oil.

Remove upper plug at rear of case and pour in two quarts of ATF +4 fluid. Reinstall plug.

You are done! Just reinstall in your rig, and enjoy your rebuilt case.
 
About how long did the rebuild take you?

Having all tools and parts ready, I would guess 3-4 hours. It is no different than doing a 231, there is not much in there. I did not have proper snap ring pliers, and discovery of bad range fork put me on long hold. It was 2 weeks to get range fork from Mopar. I also spent several hours cleaning the outside of case, and making everything was spotless in the inside. Also coming up with a solution for the needle bearing took a bit of thinking and trial and error.
 
  • Like
Reactions: jjvw
Thank you for the right up!

Did you use the second smaller needle bearing? Looks like it goes in the reduction housing to support the rear output shaft.
 
Last edited:
I am having to rebuild my 241, and I have some major concerns about the oil pump being shot. The gear inside of the oil pump seems to be quite misaligned and seized. Anyone have any advice? I fear I may be forced to buy a used or reman.