Wiring the A-518

[Tony Urwin]

I have swapped a 318 and a new A-518 from Mopar Performance into my 1948 Plymouth. I used the 2-wire A-518, the one without the lockup t/c.

I am looking for a way to power the overdrive at highway speed. I have seen several posts in the forum that suggested Jet Performance or Intermotive as companies that offered this type of switch, but I called them both with no luck.

Does anyone have a solution other than a toggle switch on the dash?

B & M has a speed-adjustable switch for lockup torque converters that might work, but I would rather not be a pioneer if someone has already worked this out.

[JVMopar]

That's how the OD is on the Dakota's. Mine had the button right on the dash.

[Tony Urwin]

Right, but that button was wired through the Dakota's computer. When you retro-fit an A-518 to an older car like my street rod, the cheap and easy way to wire the overdrive is with a toggle switch on the dash. The 2-wire overdrive like mine has 2 wires- power and ground. If you hook up a toggle switch, you don't want to engage the overdrive until 3rd gear, and you have to remember to switch it off when you come down from highway speeds. Not very convenient.

What I want is a speed-adjustable switch that will engage the overdrive at about 55-60 mph, then automatically turn it off when I slow to 55. All that was done by your Dakota's computer.

I need an aftermarket solution that I can wire to the speed sensor on my transmission and set to the proper speed. They are available for Chevies, of course, but as always, tracking down Mopar stuff is a little harder.

[JVMopar]

Mopar muscle or mopar action did a swap to a A518 in a b-body. I wonder how they did it?

[concord997]

Tony, I'm trying to get the same info, for my 52 ply. I have the 518, 88-92 tranny and and mine looks like 3 wire, hook-up. MY POINT, keep me informed, on what you find, and I'll do the same. Great post.....Don

[Tony Urwin]

Check out the B & M website at www.bmracing.com. In the products section you can find a controller called a convertor Lockup Control. Looks to me like it should work, but they weren't real helpful when I called them. The sales guy kept saying, "But this is for a Chevy!"

[John Kunkel]

A simple way to control the OD is to find the centrifugal switch pictured below, it was used extensively in the seventies for emission controls. The switch screws on the speedo connector in the tailhousing and grounds the wire at approximately 40 mph.
One pin on the transmission connector is wired to the ignition switch, the other pin wires to the centrifugal switch. The OD will engage at about 40 and drop out at about 30-35. A toggle switch in the power wire can be used to override the centrifugal switch.

[Tony Urwin]

Thanks very much for your input, John. Two questions, if you don't mind:

1) Is this switch universal for most Mopars from the seventies? If not, which models should I crawl under?

2) Do you think this shift point is high enough? Shifting to overdrive at too low a speed might be a drag (no pun intended).

Again, thanks for helping!