chipmaker

Just attempted to rebuild my np231 but Im having really bad luck. I replaced the chain, range shift fork, and bearings. When I was assembling it the rear output housing was a pain to get on almost like the chain was too tight, but I put it together any way and now the front and rear outputs are hard to turn and will not turn independently of each other no matter what position the shift lever is in. I went ahead and put it in the xj with a few bolts, left the rear drive shaft out and bolted up the front. Even in 2hi the front is still pulling. Im about to pull it back out and was wondering if anyone might know what is causing this. The range fork I used is item #4638913 shift range fork for np231/nv241 from morris 4x4. They list two forks on their website I noticed that the other fork they list has a note that says this is the np231 fork. Could they have sent me the wrong fork? Comparing the new one to the old on the work bench they look identical.

BTW it is a 1998 xj that dosent have the extension housing on the output like the earlier model 231's

CCKen

Did you buy a kit specific to your 231/year, or did you cherry pick the chain, bearings, and seals seperately?

"When I was assembling it the rear output housing was a pain to get on almost like the chain was too tight."

Maybe the chain is the wrong one. The rear cover is a bit tight going on with a new chain but shouldn't be a "pain" putting it on.

chipmaker

I phoned in the order and gave the sales person the year, and even the V.I.N. because of mutiple parts for the same vehicle on their site and I wante dto be sure I got the right stuff. But still ended up with the rear output seal for the TC with an extension housing, thankfuly the local parts house had one in stock. The chain is the same width and number of links as the old one. My old chain was toast, it was slipping when driving on level grass and had worn a small groove in the case housing. Holding the old beside the new the new looks about a link and a half shorter wich I assumed was due to wear and streching. I just split the case again at the seam of the two main housings leaving both output shafts, chain and oil pump in the rear housing. The two outputs will turn independently but the rear output still feels a little stiff.

Thekid320

Make sure the oil pump sits between the rear housing and the case not inside the case I did that with mine and it did the same thing that output housing should have grooves the oil pump sits in if not everything rubs

chipmaker

I have the pump in right, when I split it I noticed that it looks like something rubbed on the range fork. Iam wondering if the gear that the range fork controls was cocked or misaligned causing the fork to sit higher than it should allowing it to come imto contact with the gear on the output shaft. I had to run a few errands and havent been able to investigate what is really goin on, about to go take a look now

chipmaker

Oh well....pee on it! I just can't figure it out everything turns free in the back housing but as soon as I put the two halves together it gets tight and locks up both outputs. It still seems like the chain is too short because I have to work, wiggle, and cuss to get the front output shaft out the front housing and the rear output into the sync/planetary area. Seems like the chain is pulling the two shafts together at the front and causing it to bind at the drive gear/chain sprocket area. Dose anyone know how much deflection the chain should have? Is it common to get a defective chain? Dont want to (and cant really afford) to take the case to the shop but I have to do something as my DD silverado is about to kick the bucket.

freegdr

Have you seen any of these....http://www.youtube.com/results?searc..._ul4wGHSIF_ul4

freegdr

Here ya go.....http://www.pirate4x4.com/tech/billav...Case_NP231.pdf

freegdr

All parts go in front half back half goes onto ir ....

chipmaker

Thanks for the links I have watched everything youtube has to offer and researched all of the service manuals that I can find. I originaly built the case with everything in the front housing then bolted everything on the back. I split it in the middle this time to try and save the oil slinger and rear output seal because I know I will kill the slinger removing it and probably damage the seal as well. I just don't get it. I rebuild electric motors and gear boxes for a living so this is'nt my first rodeo. I swear it seems like the chain is too short. Guess I will go ahead and bite the bullet and remove the seal and slinger to see if I can figure anything out in the A.M.

One more thing the first time I put it together the right side (if your facing the rear of the TC) of the output housing would not tap all the way down with a mallet, but pulled in eaisly with the bolts. Now that I am attempting to dry fit the two case halves the right side of the housings will only tap down to the point where it has about 3/8 of an inch gap, but pulls in easy with one bolt. Dose this mean anything?

freegdr

Is case binding on shift rod ?

chipmaker

It has got to be the chain. Took off the chain and the case slid together no problem. The input and rear output assembly turns way better than it did before without stifness or binding. So now I get to try and prove my case to get a refund on this thing,should be about as fun as hearing "Turn your head and cough, Just try to relax..."

Anyone know of a GOOD replacement chain? I did'nt want to shell out $180.00 for one at the dealership, but looks like that $64.00 savings is not worth the headache I have and the hassle I'm about to go through

freegdr

Whats wrong with old chain?

chipmaker

It was slipping. In 4hi or lo it would pop loud as heck on a incline and the front tires wouldnt pull when it was popping. The previous owner neglected to check the tc fluid level and ran it dry after the rear output seal went bad, killing the range fork in the process. So, I decided to replace the fork, chain, oil pump bearings and seals. Now Im several hundred bucks into this thing and am no better of than when I started

Oh, after playing with it for a little longer I noticed that with the chain on the two outputs lock_up with each other before the teeth that actually engage the front output are evenin the sync ring that rides in the range fork

freegdr

Count links in chains yet ?