My local transmission shop stocks the parts I needed for the rebuild.
This little snap ring is critical. They tend to fail on these transfer cases (according to my research). When they let loose, the main shaft moves forward and the transfer case becomes a grinder, eating itself up. My transmission shop keeps an upgraded one that only costs a couple of bucks and doesn't fail like the stock one.
I needed a bearing driver but didn't have one large enough so I improvised with some big washers. Worked just fine. I like to heat any aluminum cases before installing bearings so they basically just sneak right in without having to get crazy with the hammer.
This picture doesn't show it well, but there is an o ring down inside that hole. It's the seal for the shift shaft. Mine was leaking originally, so I paid special attention to this one to make sure the new o ring was installed properly.
The NP241 has six planetaries. I'm told that makes it heavier duty than its smaller siblings which only have three. You can see the six gears around the assembly. They're called planetaries because the little gears orbit around the outside of the big gear in the middle just like planets in the solar system. In these pictures, I'm disassembling the planetaries and replacing the thrust washers. Its all straightforward. Just remove snap ring, take it apart, swap new washers in place of the old ones and reassemble. The only tool needed was a flat blade screwdriver for the snap ring.
You can see the snap ring around the top there.
The new thrust washers we are installing.
The is the center piece of the planetaries. It's also the splined part that sticks out of the front of the transfer case and interfaces with the transmission's splined output shaft.
There is a bearing down inside the center that you change out too. Nothing fancy to the job. I used an old wrist pin and a mallet to drive it out and my rigged bearing driver shown above to knock the new one in.
Thrust washer in place.
All back together.
The input/planetary assembly back in the case. Notice the front bearing has a built in snap ring to keep it from going in too far, and the input shaft had a snap ring on it to keep it pulled up into the bearing. What you're seeing in this picture is the front of the transfer case that bolts to the transmission adapter.
This is the place where so many transfer cases have troubles, the shift forks. There are two shift forks inside of this case. Each has three plastic pads that you replace during overhaul. The kit comes with them. No tools needed, just pull them off and put the new ones on. When these get too worn, the transfer case will jump out of gear. If yours jumps out of gear, you're looking at the likely cause in this picture.
More in next post....