NP231 SWAP, need help/advice/how to's, etc. Options

[nmetankzr2]

I know there are quite a bit of post on this topic but it's hard going back and forth to each topic and trying to figure out which way to go..

So, i am going to be doing a Swap from the NP236 Auto-crapper to the NP231...my questions are as follow:

1) What NP231 Case to get.. A regular NP231C(mid-90's), or a NP231C-HD??
2) Bolt pattern the same as the NP236?
3) how about spline count on the input/output shafts? same? different?
4) Driveshafts? need new ones? front or rear?
5) What other things do i have to do the get this NP231 ready before i rip the old one out?
6) What do you guys recommend(for those who done it)


Just looking to be pointed in the right direction...


there really should be a qwrite up for this and get it stickied (IMG:style_emoticons/default/smile.gif)

[TrailTamer]

i and kristian and miles did this, a few more did too..

for the swap, its pretty much plug and play, your driveshafts will be fine. i still use my stock ones, but could be different as yours being lifted. for the wiring, the np-236 have tons of plugs, you will only need to reuse ONE plug for speed sensor. all other plugs can be taped away or just cut off and forget it. make sure you test which plugs before start cutting. i plugged one in, it was wrong, swapped with other one, then worked that way. again make sure you get the transfer case that have piece of wire attacched to the vehicle speed sensor (VSS) thats not hacked since there's actually a plug a little farther away from the VSS itself on the donor is a plug that you can use the plug on your 236 plug plugged right in, no wiring needed. hard to explain for me. but i can get pic if needed.

when you did the swap. you will have the "service 4WD" on the indicator dash board, this can be fixed by simply pulling the "4WD" fuse out of the dashboard fuse box on driver side and pull "ATC" fuse out of the fuseblock from underhood.


for the shifter part, you will need to locate the assemlby or just get it out same truck you got your transfer case out of. to get it in, you will need to remove your center console and mount it on the 2 studs thats already there. you will HAVE TO drill 1 or 2 holes to put bolts on the front part of the assembly, pretty easy since there's already dent made on the floor for this, no guessing is needed. for the 1.5" hole for the cable itself to go through, its pretty hard as the space for the driller is very limited. we did this by using hole saw on the driller, not prettiest job but it did the job for me. VERY IMPORTANT as you get the transfer case from the donor, get the bracket that attach to the bolts that hold the transfer case to the adaptor that hold the cable as its' HARD to find, i've known this by Miles as he couldnt find it for LONG time.....
lastly, you will need to wire the transfer case shifter assembly. there's black wire off it you will need to ground it. all way back, there's yellow wire, you will need to connect that to the gray/black wire on the connector on the TCCM. the link below to txzr2.com explain it all....

(IMG:http://i153.photobucket.com/albums/s228/trailtamer/DSC01389.jpg)

lot of info can be found here
http://txzr2.com/board/showthread.php?t=1172


any question, ask

[TrailTamer]

almost forgot, you will want the NP-231 transfer case out of 94 to 96 s-series. probably snatch their center console while you're there.

your's is column shifter or floor shifter??

[Cummins ZR2]

I've been wanting to do this too. The 231 case itself is super easy to find and cheap at least in my area. The shifter has been impossible to find though. I can only find push button setups in local yards and the recyclers I have called (probably 20 different ones within WI/MN/IL) have given me no help either, saying most of the "older" pickups and blazers got crushed while scrap prices went up last year. Good luck and let me know if you find an extra shifter/console!

This post has been edited by Cummins ZR2: Jan 30 2009, 05:30 PM

[TrailTamer]

has you looked in car-part.com? thats where i found mine, it took me to search and making a few calling and i found mine in 1 hour, so id think should be same thing for you. i got it in WI BTW

[Cummins ZR2]

has you looked in car-part.com? thats where i found mine, it took me to search and making a few calling and i found mine in 1 hour, so id think should be same thing for you. i got it in WI BTW

Bastard! You got the last one, LOL. Yes I have tried car-part.com. That's where I got all the #s for recyclers in the area. I had a few that checked in their yards but largely was just told what I posted...Nothing that old...Or I got "they didn't put floor shifters in that new of truck". I was like you retard you have a listing for a floor shift t-case...Lots of places cut off the cables to get the t-cases out too.

One of these days I'll sit down and call around for an hour again.

[TrailTamer]

yeah, i hate that too, when they dont know what they're saying or what im saying. if still no luck, probably want to go to your local junk yards to physically walking through the yard to locate whatever you will need so you wont miss out a easy grab as they dont know what you're asking.

[Kristian]

Ok first off get yourself an older case of of a pre 94?(I think). The older cases will have the wide chain and will probably have a 6 gear planetary assembly but thats not why you want it. Its a fixed front output case that should allow you to use a first gen drive-shaft with u-joints on each side. Not only will the case be stronger but the front drive-shaft will be stronger as well. This will also help with front drive-shaft angles should you ever go SFA.

Wires:
You Do Not Have To cut anything on the 236 Harness. The Speed sensor wires for the rear output (tacse) are actually part of the transmission wire harness. If you feel around on top of your tcase/transmission you will find the wires that go from the transmission wire harness and run inside the tape on the tcase harness. Once those are free of the tcase harness they can be adapted/spliced into the speed sensor on the 231.

Delete the 236 harness:
To remove the 236 harness simply unplug/unclip all of the connectors from the 236 and the large connector found inside the engine compartment near the master cylinder. Once its free on both ends you will have to remove a bell housing bolt to free a metal harness hold down strap. Once thats down the entire thing can be deleted/removed from the truck.

Drilling:
Once the old console is removed you will find a few divots in the sheet-metal marking where you need to drill. You will need to drill a very large hole for the cable grommet. This is much easier with a right angle drill and a short/cut down hole saw. You can clean up the hole with a sanding bit so long as you use a slightly smaller hole saw. I used some thick rubber washers to help seal my bolt hols, inserting the bolts from under the rig through the rubber washers.

Cutting/Modification:
The front of the console will need to be trimmed to fit the 2nd gen dash. You may (Jeremy Didn't) also need to trim the bottom of the console to fit the floor.

Rear support bracket:
The rear support bracket will need to be changed. I found the bracket from the 2nd gen console could be used with modification. The top will have to be drilled for the sheet metal screws of the 231 console. The bracket will also need to be cut down and shortened. I pounded the bracket flat in the middle and cut out a section of metal to shortened the bracket. I then used some thin aluminum to clamp the bracket back together (no welder)


-Kristian (feel free to PM me)

[nmetankzr2]

TrailTamer: thanks for taking the time to write to my post..

Would a '97 t-case work?

and my truck is floor shifted... and i have breifly read thru that link you posted, thanks again... i will probably have more questions soon

[nmetankzr2]

thanks to Kristian as well ... you guys rock!! lol

[TrailTamer]

i think we need to go over Miles's house to beat him up to make a nice write-up LOL J/K

kristian probalby described better than me. however i didnt do ANY splicing or wiring work with mine, i just plug it in and go.

97' will works yes.

[TrailTamer]

mine came out of a 96' S-10

[Kristian]

mine came out of a 96' S-10

I bought a 96 also. BUT, As I said before, the older 231s have alot more to offer and If I had to do it again I would have purchased one with a fixed front output. Im working on converting my 96 to fixed front output/HD chain atm (collecting parts) I will also be installing a gen one driveshaft (if I wheel it before the SFA goes in)

This post has been edited by Kristian: Jan 30 2009, 06:18 PM

[nmetankzr2]

if i get the one out of a 97 can a swap in the wider chain??

[TrailTamer]

I bought a 96 also. BUT, As I said before, the older 231s have alot more to offer and If I had to do it again I would have purchased one with a fixed front output. Im working on converting my 96 to fixed front output/HD chain atm (collecting parts) I will also be installing a gen one driveshaft (if I wheel it before the SFA goes in)

good idea on upgrading on them. i didnt on mine i just threw it in there. but i will upgrade if i manage to break this one (stretch another chain as i did with the np-236)

[Kristian]

if i get the one out of a 97 can a swap in the wider chain??

Yes, But why? You save money and time by getting the right case the first time AND it should have a 6 gear planetary.

[nmetankzr2]

yes that is true.... but i was just thinking if i couldnt get one with the wider chain already in it.. then is it possible to upgrage the chain to the wider one...

also i figured if i get one im probably gunna open it up anyway and upgrade the weak points if there are any... what would be the weak points in this t-case???

[nmetankzr2]

from what i can see there is the vaccuum switch on the t-case (w/ the three vac connection) on the NP231... how would you set that up?

[01blaZeR2]

i have the console and t case from a 96 but will be finding a wide chain model before i do the swap. I actually have an extra console if anyone needs one. Its from an auto and is the light interior color but its painted black. I bought a 95 manual console from ebay to use as my interior is black. the paint will come right off with the right solvent and leave you with the factory color.

[nmetankzr2]

my other question is.... what do i do about the front diff pin the accuator connect to... would i have to put in a posi-lock set-up???