SYE pictorial install NP231

[87xjco]

NP231 transfer case out of a 1987 XJ
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00119.jpg
Remove 1 1/8" nut and tap off front output yoke, the instructions say to put the transfer case into 4low and remove the shifter lever. I did not remove the lever and had no problem.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00120.jpg
Remove the speedo gear housing and note the position that it was installed in.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00122.jpg
Remove the 3 15mm bolts around the rear output slip yoke housing.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00125.jpg
Remove the snap ring next to the bearing
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00127.jpg
A gasket scraper can help split this housing from the rear case half. Be carefull to not gouge the rear case half surface.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00128.jpg
After housing removed you see the oil pump and shift fork shaft
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00129.jpg
Remove the bolts around the transfer case so you can split the two halves of the case. There is this 12point 10mm bolt and two 15mm bolts with washers on them, note the location of these. The rest of the bolts are all 15mm with no washers.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00131.jpg
There are 2 slots like this that if you carefully drive a large flat screw driver into, will split the case without damageing the gasket surfaces.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00132.jpg
After case is split
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00134.jpg
Wiggle out the front output shaft and remove chain and set aside
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00135.jpg
Wiggle out the main shaft and set aside
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00136.jpg
Two gears and a sincro stay on the shaft as it is removed
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00137.jpg
You will need to transfer the two gears and sincro onto the new mainshaft
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00138.jpg
Some older model transfers like mine have caged bearings that need to be discarded, use a brass punch and set the gear on a wooden block to avoid damage as you drive them out.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00139.jpg
After the caged bearings are removed, clean and pre-lube gears
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00140.jpg
Supplied snap rings and hardware, the two matching rings are for the speedo gear and the other is the gear snap ring.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00145.jpg
Install gears and put on the new snap ring supplied.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00141.jpg
If you set the case flat it is easy to first wiggle the main shaft in thru the sincro shift collar and into the splines at the front of the case. Then install front output shaft and chain together, wiggle and turn the shaft to get it to slide in.
Then install a thin layer of silicone.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00143.jpg
The rear case half installs by sliding over the main shaft and making sure the splines for the oil pump do not bind up. Once in place make sure the oil pump tube is still seated in the oil pump at the bottom of the transfer case
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00144.jpg
First put on the forward snap ring and then slide on the speedo gear and then install the rear snap ring
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00146.jpg

Now I ran into a problem, the shift fork shaft slides in and out of the rear case half when the gears are shifted. You can see by the depth of the pens that the old housing had a deep enough hole that the shaft had full movement. The new supplied housing does not have a deep enough hole.
So I am stuck until I can call PORC and see what the deal is.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00148.jpg
I will post when I know what is wrong.

[d10shun]

Excellent write up! WHat did you use to seal up the case? I see that it is white... I have have to dig into mine to fix a leak.

[87xjco]

Excellent write up! WHat did you use to seal up the case? I see that it is white... I have have to dig into mine to fix a leak.

It is a tube of silicone for that was supplied by volkswagen for sealing a diesel oil pan. I don't think it is anything different than other silicone. Just had half a tube so I used it.

[87xjco]

Duh! I actually read all the directions and it says I need to shorten the shift fork shaft. It seems like it will be a little tricky to get the right length so that the vacuum switch will still operate though.

[Tim_MN]

Your pics and descriptions are way better than the JP Magazine, MAY 2005, sye install on pg 74.

They show the shift fork shaft and say this:

" With the rear bearing retainer housing removed, trial fit the new SYE housing to check if the shift rail bottoms out in the new housing when fully extended. If it does, you need to shift the T-case so the shift rail is as far in as it will go, then cut it off flush with the housing. Use a cut-off wheel or a hacksaw. The ideal length of this shaft is exactly 1" protruding from the housing after trimming. Most newer 231's already have the shorter shift rail. "

[mack]

get some 1" masking tape, put it on and cut, done.

[87xjco]

Your pics and descriptions are way better than the JP Magazine, MAY 2005, sye install on pg 74.

They show the shift fork shaft and say this:

" With the rear bearing retainer housing removed, trial fit the new SYE housing to check if the shift rail bottoms out in the new housing when fully extended. If it does, you need to shift the T-case so the shift rail is as far in as it will go, then cut it off flush with the housing. Use a cut-off wheel or a hacksaw. The ideal length of this shaft is exactly 1" protruding from the housing after trimming. Most newer 231's already have the shorter shift rail. "


get some 1" masking tape, put it on and cut, done.

Exactly 1" - that makes it easy. Thanks

[VegasAnthony]

just an added note to any newbs reading this
they entire t case DOES NOT NEED TOP BE REMOVED TO DO THIS
although it does make it way easier( working on your back under a lifted XJ can be horrrible on the shoulders :)

87xjco
great job on the pics and install...how about some pics of the 231 goin back into the rear of the the tranny...??
I wish I would have had a nice write up like this when I did mine..

[flexjay87]

nice job on pics and corresponding descriptions of what to do. this is the kind of info., everyone can use, as needed. let us know how the shift fork shaft turns out.

[KIAKillerXJ]

funny that you did this write up today, as ExxonValdez and myself were doing the same exact install this afternoon, on an older model case just like that, and ran into the same shift rail problem. Went and found a Dremmel and a few minutes later problem solved! Wouldva been nice with the pics like you have- great job!

[azdesertrhino]

Great write up and pix!! Thanks for taking the time to do it!! :wave:

[87xjco]

On older transfer cases the shift fork shaft has to be cut shorter. It needs to be the right length if you need the vacuum switch to operate properly.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00150.jpg
The depth measurement I came up with is 15/16", 1" is just a bit too long for the housing to seat against the rear case half.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00151.jpg
Transfered that measurement to the shaft
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00152.jpg
Then wrapped the transfer case with plastic and cut the shaft off with a cut-off wheel. Hacksaw or dremmel tool can also be used.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00153.jpg
Polished the end of the shaft and then pulled off the plastic & put a thin layer of silicone on.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00154.jpg
Installed the speedo gear housing in the same position as when removed, bolted on the housing and torqued to spec, then slid on the yoke, rubber washed and lock nut and torqued to spec.
http://i6.photobucket.com/albums/y224/87xjco/SYE/DSC00155.jpg

[Beetlejuice]

When you guys say "older transfer cases" in regards to cutting the shift fork, how old are we talking?
Thanks.

[87xjco]

When you guys say "older transfer cases" in regards to cutting the shift fork, how old are we talking?
Thanks.

Sorry, I don't know. That's all it said in the install instructions. Maybe someone else can answer.

[JeepFreak21]

Very nice! Thanks for your contribution!!
Billy

[Brian Carpenter]

I just stuck a similar 231 under my 88 and had a bad time shifting into/ out of 4wd.. turns out I was using the sensor out of the 242 I replaced which stopped the shift fork from moving freely.. with no vacuum disconnect axle I elected to use the supplied plug and "feel" if I was in 4wd hi or lo rather than letting the idiot light tell me if I was in part time or not.

[markw]

I would assume this would apply to 94 and earlier. 95 internals are different, gear teeth are pointed vs squared, etc. I'm about to do an AA SYE in a 94 case, will keep posted about the shift fork deal. I'm assuming the vaccum switch is for disco front axle, so it could have changed in 91-92 when they got rid of the disconnect D30.

Mark

[gopking]

On this thread,
http://www.naxja.org/forum/showthread.php?t=61634
they said that the NP231 has an electric switch that turns on and off the "Part Time" light on the dash when 4x4 is engaged. Would anybody be able to use these pics here to show me where the switch is located on the NP231?

[87xjco]

On this thread,
http://www.naxja.org/forum/showthread.php?t=61634
they said that the NP231 has an electric switch that turns on and off the "Part Time" light on the dash when 4x4 is engaged. Would anybody be able to use these pics here to show me where the switch is located on the NP231?

Actually it's up on the firewall on the right side below the heater hose area. It has 2 wires going to it and one vacuum hose. Here's a photo. It is not bolted up in this photo to the stock location but shouldn't be 2 hard to find.
http://i6.photobucket.com/albums/y224/87xjco/Misc/DSC00188.jpg

[gopking]

Thanks...I was under the impression that on the NP231, it was an electric swtich, not one activated by a vacuum. But I'll look for it and see if I can find it. Thanks again.

2 '98 Xjs

[gopking]

Okay...maybe I'm just not seeing it, but I can't find that 4x4 "Part Time" light swtich anywhere on the firewall. Maybe on the '98 with the NP 231 it's in a different location??? Anybody know??

Joe

[87xjco]

ttt for a buddy that can't find it

[Nevada City Sparky]

When you guys say "older transfer cases" in regards to cutting the shift fork, how old are we talking?
Thanks.

Its the vehicles that have Vacuum-disconnect front axles.

[flexjay87]

nice pics with the write up. i think it usually doesn't hurt to keep info fresh on subjects like this, i won't go into all the reasons. but i am curious if some people would view this as redundant, already covered too much etc.? i don't, but i do understand how some things seem so obvious as to be annoying, i just think this kind of refresher info is good, especially the pics. it helps those who may be reluctant to just read instructions and dive into something. you may learn a little something new each time.

[MuddinJeeper]

I think its awesome! I've never ripped a xcase apart, and had no idea how they worked in any detail, and this is good even for general info. This write up is definitely going to help my SYE install when the time comes.
Cheers

[XJ_ranger]

my pics and info - just incase someone finds them helpful...

http://www.opiebennett.com/images/Jeep/D4-ford9-swap/Day%2015/np231.htm

[flexjay87]

yeah Opie, your info. is top notch also. you sorta went above and beyond, with all the extra pictorals, and explanations of range variations etc.