94 Tranny into 87? Confused...

So after searching I'm a little confused...
I have an 87 4.0- AW4-NP231 Combo.
My 231 Bombed and while deciding what to do for a new one I came across a 94 donor vehicle for $400. Will that Tranny-Tcase combo drop into mine without any mods? Will my computer and wiring harness plug right in. I read something about 4 pulse versus 1 pulse... but I'm not sure what year that changed.

any help would be appreciated

Jeremy

I think the 4 pulse started in 1998. Someone please correct me if I'm wrong.

More importantly, you need to check the spline count. There was a 21 spline and 23 spline.

I'm willing to trade my 21 spline input shaft out of my 1995 NP231 for your 23 spline if you need

CaliGold said:

More importantly, you need to check the spline count. There was a 21 spline and 23 spline.

Click to expand...

I believe mine (87xj) is a 21 spline between the Tcase and the tranny... but if I take the 94's Tranny and Tcase together, will I have trouble matching it to my 87 4.0 & computer...

MJR runs a 95 computer on his 88 jeep and tranny, so it can't be that hard to adapt. PM him and he can give you exact details I'm sure.

just swap t-case input shafts

tomcat said:

just swap t-case input shafts

Click to expand...

Sometime around that year they changed how the helical gears are cut in the transfer case, the input shafts may not be interchangable.

The 23 spline aw4 has a slightly lower overdrive too, which may be a bit more desireable - and the mid 90's TCU's downshifted with less throttle iirc, which can be desirable on the highway with big tires.

If you're swapping the whole transmission/transfer case combination, then you don't need to worry about the spline counts on the transmission as they are at the tail end of the unit.

Jeremy, it'll work. You'll need to swap out the 94's speedo housing (electrical) to the 87's mechanical housing. It's one bolt holding the housing to the transfer.

Keep the 94 trans/transfer together for no issue with spline counts. Computer and plug are compatible.

I run an 88 trans/transfer in my 94.

Thank you John B.
That may sway me to go that route instead of spending lots of money on my busted 231...

The 87 TCU will work just fine with the 94 AW4. The sensor changes happened in 98. The spline count isn't an issue if you are grabbing the xfer case with it. The 4th gear ratio changed from 0.75 to 0.705. That won't bother the TCU although you may notice the 4-3 shifts are a few hundred rpm different than before.

I wanted to update this thread for future searchers.
I just completed putting the 94 Transmission AND T-Case into my 87. It all worked well. I did swap the Speedo Housing and I did use the 94's tranny cable which seems longer, but works fine. but everything else stayed the same. I did use the 94's tranny cable, which seems longer, but works fine. The 94's drain plug was a mother to get off, but thew t-case was nice & clean inside. I did swap my 87's T-case output shaft into the 94 (Because I have a Hack N Tap and I wanted to keep the 94's shaft intact for a better SYE kit in the future)

Drove it today and all seems well. The only problem right now seems to be getting the linkage for the T-case right. I can't get 2h, and 4l at the same time. I'm sure I just need to find that sweet spot. I also took the time to replace those top two inverse torque star bolts that are a mother to get out of the top of the engine/tranny.

I think that's everything. Hopefully it keeps working... time will tell.

Thats good to know, I'm going to need to do this soon as well. My trans is toasted and I need a 23 spline output.

I have a 91 XJ 4X4 and the tranny is going. How do I know if I have a 21 or a 23 spline tranny?

doclouie said:

I have a 91 XJ 4X4 and the tranny is going. How do I know if I have a 21 or a 23 spline tranny?

Click to expand...

You should be 23 spline.. but you should remove the transfer and count just to verify.

That is what I thought until I saw the following website:

http://www.lunghd.com/Tech_Articles/Transmission_and_Transfer_Case/Transfer_Case_ID_Project.htm

My transfer case Assy No is 5300 8209 and the Serial No 123 902.

There is a transfer case with numbers higher than both my assembly number and serial number and it has a 21 spline. That is why I am a bit nervous about just purchasing a 23 spline tranny to find that I really need a 21. I am just hoping that someone out there knows a way I can tell how many splines it is without pulling out the trans.

If you find a good deal on a good transmission grab it. You could always just swap the transfer case input gear to the spline you need to match the new trans.