Controlling a Mopar A518 transmission?

[Galane]

I have a 1941 Hudson pickup hotdrod, looking at swapping in an A518 transmission with overdrive and lockup converter to boost the MPG.

I've seen some control hacks using a couple of pressure switches and a switch on the throttle linkage. Seems a bit crude to me, ought to be room for improvement via more precise control.

Unlike the Ford AOD and GM overdrive RWD automatics that are true 4-speed, Mopar chose to go with a design that is essentially an overdrive added to a normal 3-speed automatic.

That brings the potential of being able to engage the OD in any gear, making it work like a 6-speed.

With some electronic box controlling both the OD and the TC clutch, the shifting would be really smooth and MPG maximized. There is a version of this transmission that only has the OD, no TCC. Then there's the weaker A500 model which isn't tough enough for a V8 without major upgrading.

By the late 90's these transmissions went computer controlled, which would require a very complex and expensive computer to retrofit to older vehicles.

Soooo, any ideas on reading vehicle speed, throttle position and whether or not the brake pedal is in use to control one of these transmissions?

[grswat]

I know a little about these transmissions but I may be stating stuff you already know.

The non computer controlled 518 uses a pressure governor to control shifts. So as you accelerate pressure builds and builds until it reaches a certain point then shifts to the next gear. Added into that is a detent (kickdown) cable attached to the throttle body/carburator. So if you are flooring it it will hold the gear until a different certain point. The brake pedal would only be used to disconnect the tcc.

I know a guy that had made a "6 speed" version you mentioned but unfortunately I have lost touch with him, but I know it used a toggle switch and was pretty crudely controlled and more of a hassle to control imo.

That's about all I know. You could probably find more information at on a Dodge forum site.

[Galane]

Yeah, I've seen posts elsewhere about people rigging up the overdrive to work manually, both with the Mopar version and with the aftermarket Gear Vendors overdrive on a 904 or 727.