Manual to Auto swap

[bryans87MJ]

OK I am looking into doint a trans swap on my 87 MJ 2.5L motor. Now I know with newer motors you need to get the trans computer but on the olders like an 87 did they actually have the computer?

 

Just starting my research now to be ready for the swap this winter.

[mjeff87]

If you want to swap an AW4 in it, you'll need the TCU and the underhood wiring harness it attaches to, as well as a different throttle body that has the second TPS output for the TCU. AW4's came stock behind 2.5's from 87-89 but were a very rare option. You can use a 4.0 AW4 trans body, but you'll need the specific bellhousing for the 2.5/AW4 combo, plus the torque converter. Jerry (tjbliley) and I found out the hard way that the 4.0 torque converter doesn't work.....he ended up getting a new 2.5 specific TC from a place up in PA.

 

I'm not sure if the TF 904/909's are computer controlled.

 

Jeff

[Pete M]

Be prepared that the auto will suck precious horsepower from the 2.5L. There's a reason why they were a rare option and a reason that the factory trucks came with 4.56 gears.

[oldjeep]

Most 87 MJ with auto would have had a 904 in it, not an AW4. I've got an AW4 in my YJ behind a 2.5L, doesn't really suck that much power.

 

Be aware that the 2.5L used a different TCU also, the shift points are higher. Using a 4.0L TCU with a 2.5L would really make it dog as the engine would never get up into it's power band. I've still got an extra 2.5L TCU if you wind up needing one. My aw4 is full manual so I don't run a tcu.