NP208 swap

[bluebellyday]

Well, I found it necessary to finally do the 4.0 swap in my 95 YJ after my 2.5 died a violent but quick death.

I picked up a motor, transmission and wiring harness from a local Jeeper and swapped it in. (This is another story)

This gave me a great opportunity to swap in the jeep NP208 I had picked up.

For those who do not know about this case it is very similar to the Np231 that comes stock in most Jeeps. It is drivers side drop. It has the same bolt pattern and it has the same 23 splined input as found in most Wrangler
Like the 231 it has an aluminum housing and is chain driven. Note: much larger chain than the 231

The transfer case is also a slight bit bigger and much stronger than the 231. It is used behind V8s in full size jeeps with no problems.
It also has an added bonus. It had a fixed yoke in the rear. This case is found on many full size jeeps made in the 1980’s

I did a test fit the 208 in my jeep and found it is going to bolt up with no problems.
One note: I use an auto transmission I have read that the 208 needs a 3/4 spacer if you are mounting it to a manual transmission.

Like I said the case is a little bit larger and stronger than the 231 so I raised my transmission mount 1". this enabled me to remount the original transmission skid plate. Getting rid of the skid plate drop I had before.
I have a 1.5" body lift and this gave me the room to move the 208 up the inch i needed.
My motor sits higher due to the 4.0 swap so my angles are still good.

The hardest part of the swap was the linkage. I took the shift arm off the np208 and took it to a machine shop. There, I had the arm drilled to accept the rubber bushing off the 231 shift arm. I then got a friend to lengthen the linkage rod an inch to give me plenty of adjustment room.

The full size Waggoner that the case came out of, had a CV front drive shaft. I swapped the yokes from the front to rear this put a CV yoke on the rear of the transfer case and the standard one on the front.

My speed sensor was a direct swap out. I removed the old cable drive and inserted the new Speedo gear and lined them up.


I then reinstalled the transfer case, bolted in my front drive shaft and adjusted the linkage..

Results: I now have a Transfer case that is stronger than the Np231
Plus it has fixed CV yoke in the rear No more slip yoke!

I'm now waiting on an rear drive shaft to be cut and balanced but I have driven it in front wheel drive mode and the transfer case is working well.

[bluebellyday]

I got a pm about the shift linkage so let me go into more detail on the linkage issue. This may help

As I see it there are four parts to the Transfer case shifter.

1) The shifter: this is the part that bolts to the transmission and sticks up through the floor.

2) The Adjuster: This mounts to the shifter using a rubber bushing, The shift link slides through it and is held in place by a bolt.

3) The shift link: This is a short piece of metal rod that is bent 90 degrees to connect the shifter to the shift arm.

4) The shift arm: This mounts to the transfer case
and acts as a leaver to operate the internal transfer case shift fork.

The one item here that is not changing is the Shifter it will mount in the same location on the transmission and operate the same way. Even the shift pattern will stay the same.

Now onto the Shift link. As you can imagine, over the year things do change. The old style used on the Np208 was just a rod with a 90* bend that went through a hole in the shift arm. The end of the rod then had a washer slid over it and a cotter pin placed through a small hole to keep it in place.
The new style is still a metal rod with a 90* bend in it but.. The link has a machined end that pushes unto a rubber bushing on the shift arm and the shifter.

The Shift arm is a flat piece of metal about 1.5" wide and 2.5" long. It had a hole drilled into one end through the flat sides. This allows the shift link to stick through. On the other end in a slot cut into the arm. This slot fits over a stud and raised metal area that fits into the slot. A washer and self locking nut then goes on the stud to keep the arm in place. This arm is the one area of difference between the 231 and the 208.

At first glance I noticed that the arms were different. The 231's arm is about .5" longer than the 208's and it has a hole drilled to except the rubber bushing that holds the shift link. This hole also has a "Shoulder" cut to countersink the bushing. Seeing the difference I decided to use the shift arm off the 231 and put it on the 208.
This is where I discovered the other difference
The slot that is cut into the arm is cut at a different angle on the 231. This different angle mounted the 231's arm at the wrong position to be of use. I needed to use the shift arm off the 208. This meant one of 2 things needed to happen. I needed to modify the 208's shift arm to accept the new bushing then use the 231's link or use the link off the 208 and modify it to fit the adjuster and Shifter. I decided to take the 208's arm to a local Machine shop and have them drill the correct size hole and make the shoulder cut to accept the bushing. This took less than an hour and cost under $10.

I then returned home and connected the new style link to the 208's shift arm using a new bushing I got from the dealership. This worked great problem solved.

The next issue came up when I started to hook it all up. I found that my shift link was now about 1" too short. This may be due to using the 208's shift arm or the location of the arm on the 208 is more to the rear than it was on the 231.
I made a quick trip to a hardware store and found a grade 5 bolt of the correct size then went to my friend Tony's house where he cut a piece out of the bolt and then cut the shift link, finally welding the bolt piece in-between the two halves of the shift link making it longer. Thanks again Tony

Now the pieces fell into place. I put the transfer case into 4wd high. This is the location where the shifter should be in the middle position. I attached the adjuster to the shifter using the same type bushing found on the shift arm. The shift link slides through the adjuster and is held in place then a bolt is tightened down on it.

I then took the jeep out for a test drive shifting into 2wd, 4wd high and 4wd low.

It is still working well. And the rear drive shaft goes in this weekend.

[kithut9284]

chains are for bicycles not transfer cases

[bluebellyday]

Looks like you could use more lift
those 33's must rub like mad if you go off road

Yea the d300 is a stronger case but not eveyone can aford to buy one and flip it.. :beerchug: