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1987 transmission swap


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  • 1 month later...

I've been researching this swap for my 87 2wd.

 

There were a couple of changes to the AW4 over the years.

 

87-90 the AW4 came with a deeper overdrive (0.705:1) but it has a 21 spline output shaft.

91-96 is plug and play compatible.  But the overdrive dropped to 0.75:1.  The up side is that they went to a stronger 23 spline output shaft.

 

The output speed sensor for 87-96 is the same so it will plug into the computer and work the same.  For all intents and purposes the 87-96 are easy to interchange as long as you get the transfer case with the right input spline count to match the transmission.

 

1997 is a crossover year.  They changed the plug on the transmission itself.  It is otherwise compatible with the earlier 87-96.  Swapping one in is just a matter of splicing a couple of wires to change the plug over.

 

98-01 they changed the output speed sensor (4 pulses per revolution instead of 1) and added an input speed sensor.  The computer was changed to account for this.

 

For any swap, you'll need to hook up the computer.  Fortunately, all that entails is swapping the engine bay wiring harness, including the part that fishes through the firewall and plugs into the transmission computer that lives under the dash.

 

 

My plan, that I'm working on getting parts for this week, involves an engine bay harness from a Renix equipped automatic 4x4 XJ, along with the throttle body and computers.  I'm also looking at an AW4 out of a 95 so I get the stronger tail shaft.  I'll need to make sure I get the right TV cable (from the throttle body to the transmission) to match my Renix throttle body.  And I'm sure I'll need a couple of pieces/parts that I haven't thought of.

 

I could take advantage of the opportunity to swap over to HO fuel injection and just get a 91-95 donor (or deal with OBD2 with a 96-01) and it would still work.  But I can keep my costs down if I don't swap much on the engine.  And besides, Renix makes plenty of torque where I use it.  I don't need a slight boost of top end horsepower that the HO gives me.

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