1971 FMX to AOD Conversion

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Joined
Apr 19, 2014
Messages
48
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Location
Utah, USA
My Car
1971 Spring Edition Coupe
(dressed up as Mach 1) full gauges,
351 Cleveland
Edelbrock Manifold Holley 4 Barrel, Jacobs Ignition system
I have the AOD transmission and looking for the best conversion kit. I have a 1971 coupe, 351C engine and the FMX transmission. Any advice on where to buy the best conversion kit for my specific need.

Thanks Tom



 
MY understanding is you don't need to buy the whole kit. Here is a write up on converting a 71-73 from an FMX to an AOD out of an 89 Mustang on another forum. I converted from an FMX to a T5 and did the research and found the kits out there for that were way over priced and included unnecessary items.

http://forums.vintage-mustang.com/vintage-mustang-forum/584241-71-73-aod-swap-how.html

This is also a good write up on this forum,,,,

https://www.7173mustangs.com/thread-fmx-to-aod-swap-complete-report?highlight=aod+conversion

 
It's like the AOD was made too fit. Cooler lines and drive shaft and your good to go.

 
I swapped an AOD from an '89 5.0 into mine, and all I really needed was the cooling lines, a new output shaft, adapter U-joint (AOD output shaft to factory driveshaft), a .27 oz balanced flex plate, and modify the FMX tranny mount to clear the AOD's valve body/pan.

I was lucky that a buddy pulled his AOD in favor of a T-5, and gave me everything except the TV/Throttle Cable mount up-top on the intake manifold and the output shaft, which he used for the T-5 conversion.  

I made an adapter harness (FMX/AOD hybrid) and used the AOD's factory shifter as well.  I suppose I should've shortened the driveshaft by about an inch, but it's in there with no issues whatsoever at factory length.  I tried a similar mounting bracket (pictured on the page in the link below), and it didn't fit right, so I just notched the FMX bracket instead.

Here's the place I used to research parts, and wound up buying the output shaft: https://transmissioncenter.org/shop/deluxe-aod-installation-kit-for-1965-to-1973-mustangs/  

I made the parts guy at O'Reilly Auto Parts look up the right U-Joint to fit (damned if I remember the part number now, though).  I also ordered a speed sensor with the 19-tooth speedo cable gear from Transmission Center as well, to go with my 3.00:1 rear gears.  Works like a champ, and I'm turning around 1750 rpm on the freeway at 70-ish mph. I'd also ordered some cooling lines from Classic Bend, but they were for the FMX (before I scored the AOD). Since Dave left the lines on the AOD (just clipped 'em loose from the car), I cleaned 'em up, cut to length, and used pipe clamps & flexible cooling lines to go between the FMX lines and what was left of the AOD lines. So far, so good.

Hope that helps!

 
MY understanding is you don't need to buy the whole kit. Here is a write up on converting a 71-73 from an FMX to an AOD out of an 89 Mustang on another forum. I converted from an FMX to a T5 and did the research and found the kits out there for that were way over priced and included unnecessary items.

http://forums.vintage-mustang.com/vintage-mustang-forum/584241-71-73-aod-swap-how.html

This is also a good write up on this forum,,,,

https://www.7173mustangs.com/thread-fmx-to-aod-swap-complete-report?highlight=aod+conversion

Thanks, both articles very helpful

 
I swapped an AOD from an '89 5.0 into mine, and all I really needed was the cooling lines, a new output shaft, adapter U-joint (AOD output shaft to factory driveshaft), a .27 oz balanced flex plate, and modify the FMX tranny mount to clear the AOD's valve body/pan.

I was lucky that a buddy pulled his AOD in favor of a T-5, and gave me everything except the TV/Throttle Cable mount up-top on the intake manifold and the output shaft, which he used for the T-5 conversion.  

I made an adapter harness (FMX/AOD hybrid) and used the AOD's factory shifter as well.  I suppose I should've shortened the driveshaft by about an inch, but it's in there with no issues whatsoever at factory length.  I tried a similar mounting bracket (pictured on the page in the link below), and it didn't fit right, so I just notched the FMX bracket instead.

Here's the place I used to research parts, and wound up buying the output shaft: https://transmissioncenter.org/shop/deluxe-aod-installation-kit-for-1965-to-1973-mustangs/  

I made the parts guy at O'Reilly Auto Parts look up the right U-Joint to fit (damned if I remember the part number now, though).  I also ordered a speed sensor with the 19-tooth speedo cable gear from Transmission Center as well, to go with my 3.00:1 rear gears.  Works like a champ, and I'm turning around 1750 rpm on the freeway at 70-ish mph.  I'd also ordered some cooling lines from Classic Bend, but they were for the FMX (before I scored the AOD).  Since Dave left the lines on the AOD (just clipped 'em loose from the car), I cleaned 'em up, cut to length, and used pipe clamps & flexible cooling lines to go between the FMX lines and what was left of the AOD lines.  So far, so good.

Hope that helps!
Thanks for the feedback.  Lots of good information coming from the forum.

 
OK,  the conversion is complete. I had a local shop perform the work.  I picked up the car yesterday!

Couple of questions to anyone who might know the answers:

1- The connection from the transmission to the steering column was not reattached.  I had to tie up the end so I could remove the key. Is that a problem? Is there a way to make it functional again?

2-The stock shifter worked, but it nows read 'N' when in drive. Can that be corrected?

3- Is there a way for me to determine that the transmission is shifting properly. Driving it home from the shop (about 25 miles), it seems to be shifting quickly to OD  and the gas pedal becomes hard to push. I understand the setting of the TV cable needs to be done correctly or damage to the transmission can occur.  How can I be assured it is? 

Thanks for any advice.

Tom

 
#2, isn't this the job of your local shop to test if shifter is well aligned?

#3, on my t-bird 93 (and was same on 91) the trans will not go OD if bellow +-60 kmph (+- 37 mph) reached and if you do not ask much of the engine.

gas pedal hard to push,

Its a cable, so there should be no change, unless you have something on the throttle body that is "hard" connected to the trans. Like a kickdown lever or cable.

 
Last edited by a moderator:
1- You'll probably have to make your own shift lever or add to the existing lever so you have a point to connect the lockout rod to.

2- Where do park, reverse, neutral, and L show on the indicator? Are you sure it's going into park? The shift rod probably needs adjusting and I'm betting the rod isn't connected to the shift lever the correct distance from the shift lever shaft.

3- Something is definitely not right, may be the way the TV cable is connected, may be to the wrong location, or not adjusted correctly. You really shouldn't feel any difference in the throttle pedal when driving.

I wouldn't drive it much, until you get a reliable and knowledgeable mechanic to look at it, obviously the one that installed it didn't finish the job correctly. There's more to it than just bolting the transmission in.

One of my favorite slogans - "If you want it done right do it yourself".

 
If it's shifting too quickly and going into OD below 40mph, the tension on the TV Cable is too low (I made the same mistake when I first installed mine).  Mine was because I had the bracket for the TV cable too close to the carb, so there was a little bit of slack in the cable.  When I moved it back slightly and added a few millimeters of tension to the cable, then it wanted to run up to 2800-3000 rpm before shifting into the next gear - no matter how fast I was going.  When I backed off the tension and set the cable to absolute zero/neutral (no tension, no slack), it's all perfect.

I read an article about how the factory set the tension on TV cables: they would put the cables into the throttle/TV cable bracket, adjust the slider so there was zero tension & slack, the clip the TV cable adjuster into place... no pressure gauge settings needed (since they didn't actually run the cars on the assembly line).  This is how mine was done, since I had the factory cable along with the rest of the factory stuff, I'd left the adjuster alone and moved the bracket around.  Since I set the cable into pretty much the same position as the factory would've done it, everything's now working correctly.

I would check that and give it a quick drive.  If it doesn't help, then definitely take it back to the shop.

Also, I used the factory '89 Mustang shifter on mine, so the letters were all jacked up.  I just rubbed 'em off the rest of the way and got some stick-on letters from Hobby Lobby. I drove it for a long time not even worrying about the letters, since the transmission's pretty standard - all the way forward is Park, next is Reverse (which can be slid into Neutral, which can be slid into Drive (w/Overdrive), then 2nd and 1st at the end (which can both be slid back into 2nd, the Drive from 1st).

The ignition lock-out on my steering column is to the left... I'd planned on zip-tying it up and out of the way (but never got around to it) - I never hooked mine back up because I forgot what that rod was for and kind of lost it after a few years of working on other stuff.  Worse case scenario, if you have any issues of the key not working as a result of the lock-out ring rotating back into the key lock position, just grab the ring on the column and rotate it back to 'disengaged.'  It won't affect anything else except the key lock, which will just make you scratch your head for a minute until you remember to rotate it back to 'disengage.'  Unless someone as more information on its functionality, I don't see it as a safety issue or anything like that - more of a nuisance since you can't just remove the piece.

 
1- You'll probably have to make your own shift lever or add to the existing lever so you have a point to connect the lockout rod to.

2- Where do park, reverse, neutral, and L show on the indicator? Are you sure it's going into park? The shift rod probably needs adjusting and I'm betting the rod isn't connected to the shift lever the correct distance from the shift lever shaft.

3- Something is definitely not right, may be the way the TV cable is connected, may be to the wrong location, or not adjusted correctly. You really shouldn't feel any difference in the throttle pedal when driving.

I wouldn't drive it much, until you get a reliable and knowledgeable mechanic to look at it, obviously the one that installed it didn't finish the job correctly. There's more to it than just bolting the transmission in.

One of my favorite slogans - "If you want it done right do it yourself".
Thanks for the feedback. it is definitely going into park. The movement between the difference gears i.e. P, R etc is much shorter on the AOD vs my FMX. I'll see if adjusting the shift level rod makes a difference. 

The shift lever for the lock out will not fit on the AOD. Fabricating a new one may be the solution.

 
If it's shifting too quickly and going into OD below 40mph, the tension on the TV Cable is too low (I made the same mistake when I first installed mine).  Mine was because I had the bracket for the TV cable too close to the carb, so there was a little bit of slack in the cable.  When I moved it back slightly and added a few millimeters of tension to the cable, then it wanted to run up to 2800-3000 rpm before shifting into the next gear - no matter how fast I was going.  When I backed off the tension and set the cable to absolute zero/neutral (no tension, no slack), it's all perfect.

I read an article about how the factory set the tension on TV cables: they would put the cables into the throttle/TV cable bracket, adjust the slider so there was zero tension & slack, the clip the TV cable adjuster into place... no pressure gauge settings needed (since they didn't actually run the cars on the assembly line).  This is how mine was done, since I had the factory cable along with the rest of the factory stuff, I'd left the adjuster alone and moved the bracket around.  Since I set the cable into pretty much the same position as the factory would've done it, everything's now working correctly.

I would check that and give it a quick drive.  If it doesn't help, then definitely take it back to the shop.

Also, I used the factory '89 Mustang shifter on mine, so the letters were all jacked up.  I just rubbed 'em off the rest of the way and got some stick-on letters from Hobby Lobby.  I drove it for a long time not even worrying about the letters, since the transmission's pretty standard - all the way forward is Park, next is Reverse (which can be slid into Neutral, which can be slid into Drive (w/Overdrive), then 2nd and 1st at the end (which can both be slid back into 2nd, the Drive from 1st).  

The ignition lock-out on my steering column is to the left... I'd planned on zip-tying it up and out of the way (but never got around to it) - I never hooked mine back up because I forgot what that rod was for and kind of lost it after a few years of working on other stuff.  Worse case scenario, if you have any issues of the key not working as a result of the lock-out ring rotating back into the key lock position, just grab the ring on the column and rotate it back to 'disengaged.'  It won't affect anything else except the key lock, which will just make you scratch your head for a minute until you remember to rotate it back to 'disengage.'  Unless someone as more information on its functionality, I don't see it as a safety issue or anything like that - more of a nuisance since you can't just remove the piece.
Thanks for the response. My biggest concerns is how it is shifting. I'll try your suggestion and let you know how it works. I am concerned the transmission shop does not know how to adjust the TV cable correct.

Tom

 
It sounds like the shift rod is connected too close to the shifter shaft on the shift lever on the transmission. Did you use the Lokar shift shaft and lever with the slot in the shift lever?

 
It sounds like the shift rod is connected too close to the shifter shaft on the shift lever on the transmission. Did you use the Lokar shift shaft and lever with the slot in the shift lever?
AOD_under_hood.jpg


Don / et all.  Please see attached picture. It is the set up for the Carb and knick down. I don't see any change from my original set up. I expected to see a Bracket and TV cable. 

With this set up, I assume there is no way to adjust the shift pattern.........correct?

Tom

 
You would have to adjust the shifter linkage and pattern under the car, on the transmission.

Did you give them a TV cable to install? Or tell them to, and they charged you for one?

It looks to me like they cobbled together something from your FMX to use as the kickdown, which obviously does not work.

 
I would suggest that you stop driving or even running in Park in the driveway immediately. I knew of a couple people who smoked their AOD transmissions without the proper cables and adjustments. I would also suggest a Lokar cable set up if the factory type is not handy.

Thanks, Jay

 
I agree with Jay, knowing now that they didn't use the right set-up.  The TV Cable is a MUST for an AOD... the shift-shaft, not so much.  Seeing the shift-shaft there instead of a TV cable explains pretty much all of your problems.

Good luck!

 
I completed the swap.  I am enjoying the cursing in overdrive!  So, only issue is the back up lights. Any suggestions on how to hook them up?

Thanks Tom

 
TFowler,

The back up light switch is internal to the transmission on the AOD. It is above the selector shaft and has a 4 plus wire connector. I am sure you can google for a wiring diagram for a late 80's or early 90's mustang to figure what wires needed to make the B/U lights work with your mustang harness.

thanks, Jay

 
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