aw4 231 swap.

[rip_1986]

Ok fellas i have a 89 4.0 aw4 231j, well somthing is bound up tight as hell in the t case and can't get it outta 4high tryed beating it out and won't go. I have a 231 out of a 99 xj auto. Will the 231 out of the 99 bolt up to my aw4?

[MuddFoot]

no the spline count is different from one case to the other. 

[Blue XJ]

No it won't, the 89 has a 21 spline input, the 99 has a 23 spline input, also, the outputs are a different style for the rear driveshaft.

[Bensquire]

I am a newbie, so please bear with me on this.  I was checking the specs on the NP231 and it states that it is adaptable to the AW4 for model years 1988-2001.  What am I missing or failing to understand?  

 

Here is a link to the site I was looking at http://www.novak-adapt.com/knowledge/np231.htm

[mvusse]

The AW4 changed from a 21 spline output to a 23 spline output in 1990 or so (not quite sure of the year). So your transmission has a 21 spline output shaft and your transfer case has a 21 spline input shaft. The 1999 transfer case has a 23 spline input shaft that bolts up to newer AW4 transmissions, but not your 1989 one.

 

To make the 1999 one bolt up to your transmission requires replacing the input shaft with a 21 spline one. For one thing, this requires complete disassembly of the case. And then you need to find one because your 1989 input shaft will not work. In 1994 the cut of the gears changed inside the transfer case making your 1989 input shaft incompatible with the 1999 case. On top of there are also different LENGTH input shafts that depend on the transmission it bolts up to.

 

Unless you have easy access to a 1987-1989 (1990?) transfer case to swap in I would start by removing your current case and taking it apart to see where the problem is.

 

Or just remove the front driveshaft and drive your truck in rear wheel drive only until you find the correct transfer case.

[Incommando]

Part of the confusion may be that, IIRC, an AW4 attached to a 242 has always been 23 spline? Or am I misremembering?

[rip_1986]

Ok so looks like i just hve to gut the one to fix the other. Thanks guys

[mvusse]

Ok so looks like i just hve to gut the one to fix the other. Thanks guys

 

As I stated in my last message, you can't. The cut of the gears on your 89 transfer case is different than the cut of the gears in the 99, so the input shaft WILL NOT swap over between the two cases. For the input shaft to swap into a new transfer case, the new case need to be from 1993 or older.

[Rockfrog]

The input gear is splined to the planetary assembly, there is no gear pitch to worry about. The 89 input gear can and will swap into the late model planetary. ONLY the input gear itself (once removed from the assembly).

Only those parts with a gear face (sun, planets, annulus) are of issue and non compatible due to the gear pitch change. The main shafts are compatible, but to use one in the other requires removal or addition of needle bearing depending on how you swap. That's the simple explanation, but the 231 did not really change much over it production. Other than the aforementioned pitch change its all the same parts. Earlier cases did have a brass synchro, whereas the later case did away with it by casting the 'synchro' into the assembly, but again, parts are still cross compatible by using similar generation parts per component assemblies inside the 'case.

Using the 99's output yoke would make it easier, but you can swap the entire rear output housing from the 89 onto the 99 to make it compatible with your current shaft. Front output yokes are the same. Shift lever will be the same XJ to XJ.

[ParadiseMJ]

Really you'd be much better off finding a 90 or pre 90 t-case at a junkyard or on CL.  A quick inspection thru the fill/drain hole should tell you if there is metal in the case and/or if the chain is in decent shape. When I swapped the AW4 into my MJ I got a used case for $60, and slid it right in there. It was the ONLY easy part of the swap.