FMX swop for AOD

@MaddMike
Regarding your question for the shifter. If of any use. For the AOD swap from an FMX, there are 2 important points for the shifter to fit perfectly.
First on the trans side, you need make sure the lever is on top as otherwise P becomes 1. Not sure if the 4r70w was mounted in different vehicles with the lever down as for the older AOD, but doesn't hurt to check before install the trans as you'd then need inverse it, and to do that, you're better off the car.

Then there is the matching dial issue. On an FMX, to go thru each gear travels the lever travels more linear distance than on an AOD.
So in order to have both the dial inside matching each gear and have the travel distance you have 2 choices. Alter the lever so the radius from its pivot to the hole that connects to the rod gets bigger or smaller (this way the linear distance of the rod increases or decreases), Or alter the lever of the shifter itself.
I went for the latter, as it would be easy to redo in case my calcs were wrong...

What I did is simply measure the travel distances at the dial (in car) and at the base. (right top on pict) and projected the travel distance of both the lever on trans of my FMX and the AOD. Using basic math to have the perfect match for the lever, (or even more simple, a compass if you work at scale 1 to draw the circle from the distance lines), I needed move the pivot up by +- 3cm. As its a S shape and it was on the fold, I have cut it and welded it back with the offset. As a result, the dial inside matches all gears and all the safety switches mechanism remains unchanged and works as with the FMX.

I don't know if for the 4r70w it's more easy to alter the lever on the trans vs adapt the shifter, but if you want perfect match inside for the dial, you will have to go thru similar work if you want to keep the original shifter.

May sound complicated, but once you're in it will all make sense and you'll see its easy

mrgmhale said:

The AOD neutral safety/backup lamp switch it totally different. I ordered a pigtail connector for an AOD, and spliced in the wires from our original C4 neutral safety/backup lamp/ignition interlock switch wiring. Here is a YouTube video showing how I did that for our 1973 Mach 1 AOD transplant project last year:




Following is the s\description from that YouTube video, which includes where I got our pigtail, and the part #:

For our 1973 Mustang C4 to AOD swap project I needed to get the original vehicle wiring to work with the AOD Neutral Safety/Backup Lamp Switch. The AOD came with its own Neutral/Backup Switch installed, but the old C4/FMX/C6 Neutral/Backup Switch connector does not plug into the AOD switch directly.

I ordered an AOD Neutral/Backup Switch pigtail from Summit Racing.I then spliced the AOD pigtail wires into the old C4 Neutral/Backup Switch wiring harness. The resulting pigtail with the C4 harness end can now be plugged into the Mustang wiring harness.

The part # for the AOD pigtail from Summit Racing is RFW-PG057:

https://www.summitracing.com/parts/rfw-pg057

Click to expand...

mrgmhale said:

Where does the original wiring come from,

Click to expand...

mrgmhale said:

The AOD neutral safety/backup lamp switch it totally different. I ordered a pigtail connector for an AOD, and spliced in the wires from our original C4 neutral safety/backup lamp/ignition interlock switch wiring. Here is a YouTube video showing how I did that for our 1973 Mach 1 AOD transplant project last year:




Following is the s\description from that YouTube video, which includes where I got our pigtail, and the part #:

For our 1973 Mustang C4 to AOD swap project I needed to get the original vehicle wiring to work with the AOD Neutral Safety/Backup Lamp Switch. The AOD came with its own Neutral/Backup Switch installed, but the old C4/FMX/C6 Neutral/Backup Switch connector does not plug into the AOD switch directly.

I ordered an AOD Neutral/Backup Switch pigtail from Summit Racing.I then spliced the AOD pigtail wires into the old C4 Neutral/Backup Switch wiring harness. The resulting pigtail with the C4 harness end can now be plugged into the Mustang wiring harness.

The part # for the AOD pigtail from Summit Racing is RFW-PG057:

https://www.summitracing.com/parts/rfw-pg057

Click to expand...

Where does the original wiring come from? All I have is wiring that goes into the shifter. Is that supposed to be cut? The FMX had no wiring going into it that I can find.

Thanks!

jakosaur said:

Where does the original wiring come from? All I have is wiring that goes into the shifter. Is that supposed to be cut? The FMX had no wiring going into it that I can find.

Thanks!

Click to expand...

On my c4 the original NSS was bolted to the driver side of the tranny at the shift shaft. I used the c4 NSS wiring to splice into the AOD pigtail. The part # and vendor in purcased from is provided in the YouTube video description. The video link is in the one pdf file I attached to my prior posting in this thread. I am on my iPhone, otherwise I would open the pdf file myself and provide you the link and vendor info in this reply. I am pretty sure I got the AoD NSS pigtail from summit racing. The video is worth tracking m down and watching (Listed in the “parts and vendor” pdf I attached previously in this thread). It is a fairly simple thing to do. If your NSS is mounted inside your floor shifter (some were) you can still use that switch’s harness to splice the pigtail into so the vehicle main harness is not modified.

jakosaur said:

Where does the original wiring come from? All I have is wiring that goes into the shifter. Is that supposed to be cut? The FMX had no wiring going into it that I can find.

Thanks!

Click to expand...

If you have the original NSS, whether it was located in the shifter housing or the Side of the tranny, you can use the wiring on the switch side of the NSS that then connects to the main harness. If you do not have a NSS you “could splice directly to the vehicle wiring harness, but personally I would prefer to not do that. I suggest buying a new NSS and use the wiring to its plug to splice into, so you can then push that NSS into the vehicle harness after aoikicing it into the AOD pigtail as Shaun in the video I provided in a reply previously in this thread.

I hope that clarifies the way I feel is best to handle the NSS adaptation to the AOD. If not just let me know via this thread or email me at [email protected].

I did find it eventually: inside the car! The NSS for the FMX wires into the shifter housing, so my understanding is that there's no need to wire into the AOD. I have the original AOD pigtail if I need it, but unless the transmission needs to be wired in for some reason, it should all work without the transmission installed. Am I crazy?