Auto box update /options .

Ramrodfunk

I've been on the internet lately researching either a rebuild of my tired aw71 or replacement.

My research has shown that variations the aw 70/71/72 was used by many makers under different part number up until 2005 in a Miata/Mx5. Most are differenciated by the out put shaft and bell housing. Some bell housings are not removable I believe.

Firstly, could I put an aw72 in a 240 if I change the out put shaft?

Could I source an aw72LE (A44DE/03-72LE),L=lock up and E= Electronic, from a Kia Sportage '98-'02 and install that into a 240?

I believe the "E" gives the box the ability to be used like a manual similar to my XC60' s "sports mode" shifter. There is a guy that makes that sports shifter addition for other manufacrurer's cars in the states.

It seems do-able in theory. Any insights. I thought it would be an interesting discussion anyway.

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Major Ledfoot

Ramrodfunk Firstly, could I put an aw72 in a 240 if I change the out put shaft?

There's no need to change the output shaft. An AW72L from a 16V engine is the same external physical dimensions as any AW70 or 71. IIRC, the 72L has a 1310 flange. Flange changes are just a bolt and R&R. But the 72L was set up for a 16V engine that has its peak torque at about 4000 RPM.

If you already have an AW71L, it's worth rebuilding. The 71L is factory rated up to 240 Nm - plenty for a mild +t or any NA road use. As far as slushboxes go, they're pretty solid and reliable, especially when well maintained, and are even pretty tolerant of abuse. (Wonder how much ramrod wants to do a rebuild? Heh, I need a couple done....)

OTOH if you want to go crazy with a different auto box, you might be better off finding the redblock bellhousing for an old, dead BW35 or BW55 (which unbolt from the transmission) and getting somebody to cook you up an adapter plate between the BW35/BW55 pattern and something else. You'll need someone very good to do that; tolerances are critical.

ramrod

As these transmissions are a specialty of mine I will chime in

Does your current transmission need a rebuild? Or, what is it doing to make you want to replace it?

Ramrodfunk

ramrod My wagon was ok last time I drove it, 5yrs ago but my '91 240 sedan' s is tired, slips and shudders.

I mostly want to discuss upgrading aw7*'s much like people ungrade to T6 manual boxes etc.

jamesinc

I ran a 72L behind a B23 for a while and I didn't love it. As @Major Ledfoot says, it's setup for the torquier 16V motor. Important to use the correct diff ratio too although if you're replacing another AW7x then you should be fine.