Transmission question

[Thepepenator]

I have a 1992 Mj that I am looking to make 4x4. I bought an 89 Mj Transmission and T-case for a decent price that I was thinking of putting it on my 92. I was doing more research and I found out that from the 90's the speedometer now is electronic. (Or something like that) 

Will putting this transmission mess with my speedometer? If so, what can I do to get it to work properly? 

 

I know its possible to convert a AW4 to 4wd if you change the output shaft and adapt the t-case, will this be a bit easier or more convenient?

The reason I am thinking of this is because I would like to keep my mj as close as possible to what it came like originally, and my transmission has way less miles. 

 

 

 

I would appreciate any of y'alls jeepxperience :) 

[DirtyComanche]

Use your flexplate.  The speedo drive adapter from your 2wd trans 'should' work on the tcase you bought.  If not the parts are readily sourced from an XJ.  With a 4wd the speedo is driven off the tcase so it still functions correctly in low range.

[87MJTIM]

I'd be concern if the 89 is a BA10.  That was the year Jeep switched from the BA10 to the AX15.

 

If it is a BA10, the tcase will not bolt to an AX15.  The tcase behind the BA has 21 splines, the tcase for the AX has 23 splines.

[Green Mesa XJ]

You don't want to try to convert the transmission to 4wd, it's more involved than just swapping the casing around.

 

I think the 89 aw4 and 231 are the 21 spline and in 1991 they became 23 spline. There might be some harness differences for the plugs on the 89, but a aw4 is very similar all the years they used it with minor changes like plugs and spline count where the transfer case attaches.

 

Far as the speedometer goes I believe you just need to get the speed sender for your year and the right gear for the transfer case.

I don't think the the case changed much, I'm rebuilding a 1992 231 case to go in a 1985 XJ with a speedometer cable, I'm swapping. the speed gears from a 1988 np231 into the 1992 np231 case. I'm also putting in a ax15, but it's all still a work in progress.

 

Might be able to swap the sender and gear off the transmission if the parts are the same, I'm guessing the gear will probably not be interchangeable, don't know about the sender though the plug should be the same 2wd or 4wd.

 

I'm sure somebody who's done the swap will give you all the details you need to look out for.

 

 

Edit : slow posting somebody is already filling in the details.

 

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[Thepepenator]

I'd be concern if the 89 is a BA10.  That was the year Jeep switched from the BA10 to the AX15.

 

If it is a BA10, the tcase will not bolt to an AX15.  The tcase behind the BA has 21 splines, the tcase for the AX has 23 splines.

Well its an automatic so it is an AW4 

[Thepepenator]

You don't want to try to convert the transmission to 4wd, it's more involved than just swapping the casing around.

 

I think the 89 aw4 and 231 are the 21 spline and in 1991 they became 23 spline. There might be some harness differences for the plugs on the 89, but a aw4 is very similar all the years they used it with minor changes like plugs and spline count where the transfer case attaches.

 

Far as the speedometer goes I believe you just need to get the speed sender for your year and the right gear for the transfer case.

I don't think the the case changed much, I'm rebuilding a 1992 231 case to go in a 1985 XJ with a speedometer cable, I'm swapping. the speed gears from a 1988 np231 into the 1992 np231 case. I'm also putting in a ax15, but it's all still a work in progress.

 

Might be able to swap the sender and gear off the transmission if the parts are the same, I'm guessing the gear will probably not be interchangeable, don't know about the sender though the plug should be the same 2wd or 4wd.

 

I'm sure somebody who's done the swap will give you all the details you need to look out for.

 

 

Edit : slow posting somebody is already filling in the details.

 

Sent from my iPhone using Tapatalk Pro

How do i check to see what gear ratio my t-case has? 

[Thepepenator]

Use your flexplate.  The speedo drive adapter from your 2wd trans 'should' work on the tcase you bought.  If not the parts are readily sourced from an XJ.  With a 4wd the speedo is driven off the tcase so it still functions correctly in low range.

Would the speedo drive adapter just bolt up, or will i have to find some adapter for it? 

[DirtyComanche]

I forgot, the TV cable is different between 87-90 and 91+.

[Green Mesa XJ]

 

You don't want to try to convert the transmission to 4wd, it's more involved than just swapping the casing around.

 

I think the 89 aw4 and 231 are the 21 spline and in 1991 they became 23 spline. There might be some harness differences for the plugs on the 89, but a aw4 is very similar all the years they used it with minor changes like plugs and spline count where the transfer case attaches.

 

Far as the speedometer goes I believe you just need to get the speed sender for your year and the right gear for the transfer case.

I don't think the the case changed much, I'm rebuilding a 1992 231 case to go in a 1985 XJ with a speedometer cable, I'm swapping. the speed gears from a 1988 np231 into the 1992 np231 case. I'm also putting in a ax15, but it's all still a work in progress.

 

Might be able to swap the sender and gear off the transmission if the parts are the same, I'm guessing the gear will probably not be interchangeable, don't know about the sender though the plug should be the same 2wd or 4wd.

 

I'm sure somebody who's done the swap will give you all the details you need to look out for.

 

 

Edit : slow posting somebody is already filling in the details.

 

Sent from my iPhone using Tapatalk Pro

How do i check to see what gear ratio my t-case has?

the transfer case is set from the factory, ratio is on the tag. To get the speedometer accurate you chose the gear that best corresponds to your tire size.

 

Hang on I'll be home in a bit. I'll get a picture of what the speedo gears look on The transfer case.

 

 

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[DirtyComanche]

 

Use your flexplate.  The speedo drive adapter from your 2wd trans 'should' work on the tcase you bought.  If not the parts are readily sourced from an XJ.  With a 4wd the speedo is driven off the tcase so it still functions correctly in low range.

Would the speedo drive adapter just bolt up, or will i have to find some adapter for it? 

 

 

Should just go onto the existing drive gear in the tcase.  Unless there is different styles that aren't the same, but I don't think so.  You can test fit it by removing it from the truck and trying it on the tcase, it will be obvious if it works or not.

[Green Mesa XJ]

I'm not sure what the aw4 2wd sender and gear look like.

I've got a picture of what the 92 np231 transfer case looks like to give you an idea of what you'll need to set it up on yours

 

1992 np231 speedometer sender and gear.

 

1992 np231 indicator switch

 

And here is what the gear looks like in general, different color indicate which ratio it is and which tires size it corresponds with. I don't recall which one this is, it was at hand is all.

 

The setup on the 1989 transfer case should look like this

 

With a vacuum switch for the indicator and to engage the CAD on a disconnect axel (which you should avoid when you add a front axel to yours.)

 

 

If I've confused anything please feel free to correct the record.

 

 

 

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[DirtyComanche]

The cable drive to signal converter in the first picture can be unscrewed from the drive gear assy and put onto the other tcase, and I believe the 2wd trans used the same setup.

 

Somebody like Hornbrod that knows his truck intimately could answer that for sure.