XJwonders

To begin, I have a 1999 xj with aw4 and np231 with 122000 on the clock. I just have a couple of questions relating to rebuilding. I really hate doing same thing twice...

I'm about ready to do the sye install on my transfer case. Advance adapters SYE kit.

I know the previous owner probably never used the 4x4, and I'm the only one who uses 4x4 more.

I know people here say that usually would be great idea to replace the chain when doing sye upgrade.

My questions are,

1) my friend says that if the previous owners never use 4x4 much then there's no need to replace the chain, it apply to those who use the 4x4 extensively. (His reasoning was because the chain would be worn down by using 4x4 a lot).
Should I still replace the chain anyway or should I save my money?

2) what about the bearings and seals? The new tail housing from the sye already have new seal and bearings on it, but what about the ones on front driveshaft side and output from transmission side? Would it be a good idea to replace those as well? Would those be expensive?

3) I am running 31s but when I have money, I will be running 33s, am I able to change out the speedometer gear without taking apart the transfer case again?

4) The sye kit came with a blue plastic gear. I am not sure what size tire it is for, am I able to find out what size tire it is for?

5) What type of fluid should I use to refill the transfer case? A lot of people here say ATF 3.
I'm wondering about the Lucas gear oil, did anyone do that before? What would happen if I used wrong oil/fluids?

That's pretty much it so far.

If there's anything else I need to know, tell me. Thanks for reading!

salad

1) Placing the chain under load is what causes stretching. Indeed its just been spinning most of its life it should be fine. However, #1 rule about used cars is that the PO is full of ****. You'll have to see what its like when you get in there. If you can afford it, I might suggest just returning the new chain if it doesn't seem to need it.

2) ALWAY new seals, bearings I wouldn't skimp on. These are main cost of a rebuild unless something's broke. If you can find a kit you'd probably save. At the least though I'd replace the big output bearings - you've got a new main shaft one with your SYE, so get a Timken for the front. Hopefully the needle bearings don't explode everywhere on you! (Mine look fine)

3) Yes, the speedometer pinion gear is very easy to get at. Just pop the one bolt holding the speed sensor in. If you're going up to 33s you should consider regearing your axles too.

4) Probably for the main shaft - you'd have to ask whoever made your SYE

5) The NP231 will run on almost any ATF. Chrysler, Ford, and GM fluids throughout the 80s and 00s were used. Apparently synthetic 5w30 is an excellent choice ad it reduces misting (Rockland Standard Gear has a published article on this). Don't run gear oil

You'll also need new oil slinger. And don't pry the aluminum because it nicks really easily. Get a good set of snap AND lock ring pliers. I'm on my phine right now but there are a few good YouTube videos out there. I also printed off the FSM section on the NP231 which helped a lot. There are probably copies out there...

XJwonders

Thanks for your input. May I ask what is an oil slinger?

I think probably would be best to replace all the seals and then the bearings if it look sketchy.

How much would a set of seals go for? And how much would a chain cost?

Well how much do u think the entire project would cost me? Seals, bearings, chain and fluids?

salad

Check out Quadratec or Rock Auto for some ideas. Quadratec has a parts breakout image thats helpful. Chain I think is $80-$100 range, oil is cheap lol.

Oil slinger will become apparent once you look at a parts diagram... Kind of important if you're going to do a rebuild

chipmaker

You will become very famuliar with the oil slinger, it is a PITA to get off. IMHO stay away from cheap chains I recently rebuilt my 231 and ended up having to take it to a transmission shop because the after market chain I bought was too short and I couldnt figure out why my TC kept binding on reassembly. Long story short it cost me a pretty penny more in the end than the diffrence in price between the cheap chain the one from mopar. You can pick up the mopar chain for around $170. Also as stated before invest in a good set of snap ring pliers for earless rings, you can get a set of craftsman for like 15 bucks.

XJwonders

Thanks guys. How much oil I need to fill it up? 4 or 5 quarts?

salad

2.4 pints lol

SeriousOffroad

Slinger?
There's no slinger in an NP231, it's got a pump.

salad

That parts diagram doesn't show them actually. May be a 97+ thing since there's the silly tail shaft extension on there too.

There's one on both the front and main outputs concealing the seals. Here's a picture of the rear slinger from a 97+



I destroyed mine getting off of the main shaft, it was rather seized. I'm not 100% sure if my front one is integral to the yoke intentionally or by rust.

SeriousOffroad

That's not a slinger, it's a dust shield.

kennzz05

since its mounted AFTER the seal what would it be slinging

SeriousOffroad

It's on the outside of the t-case...what's it going to sling?

Slingers move oil/lubricant.

Even the Jeep calls it a dust shield.

XJwonders

What would happen if I over filled with fluid?

SeriousOffroad

You might blow a little out the vent tube.

You'd have to really try hard to over-fill though. Once the ATF starts dripping out the fill hole...stop.

XJwonders

Thanks all of you.