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Narrowly averted disaster - FMX warning!

2ndgen

Member
I dodged a bullet!

My total restoration originally had an FMX transmission which I changed out to a AOD with a 3200 stall speed converter. I bought one of the linkage conversion kits and hooked it up to the stock shifter. The FMX shifter is different than the other automatic shifters because the FMX does not have a neutral safety switch - instead it is located in the shifter itself.

When I hooked up the shift linkage I verified the range and put it in park. When I went to fire up the engine for the first time it would not crank and I traced the problem back to a mal-adjusted neutral safety switch. I fixed that and ran the shifter through the gears several times and put it back into park...

What I didn't realize was that the shift linkage was just a bit too long, and after adjusting the neutral safety switch and running the shifter back and forth, the tranny did not go into park; it was in reverse!

I happily started the engine, set the initial timing, worked on the idle mixture, blipped the throttle a few times (yikes! glad I had a loose converter!) all with the front end on jack stands and the rear tires on the ground. To make matters worse the brakes were not plumbed and the parking brake was not connected. (Heck there is no steering wheel and the interior is stripped too!).

I bled the brakes this weekend and lifted the rear wheels to break in the new differential gears. Imagine my surprise when I started the car and saw the wheels spinning backwards! Hmm.. lets see...

no brakes - check
no steering - check
car parked in the driveway behind the Mustang - check
potential drop off jack stands onto detailed front suspension - check

I could just picture myself under the hood blipping the throttle and having the car launch into reverse!!! Note to others - if you use a FMX shifter, double check that your tranny really goes into park!!!

-Rory
 
You don't know ..... YES you do know how lucky you are !!!!
Light a candle and say some prayers.
You could have make a mess out there !!!
 
Wow glad to hear nothing bad happened. So is the C6 and C4 shifter the same with the FMX being a different shifter?
 
both the C4 and C6 use the same neutral safety switch on the trans and the same shifter, the rod is different however, for the C4 and C6.
 
I always say it is better to be lucky than good, and yes I really do say that. :)

fd
 
Well you sure don't have to buy a pair of brass balls, cause it's obvious you already have them by starting the car with no brakes and steering while the rear tires are on the ground :lol Good to hear you didn't get hurt.
 
I was so sure I had it in park! After all I manually verified it when I was under the car puting the new linkage on....

At first I thought "this is great, since the neutral safety switch is in the shifter I don't have to splice any wires!".

Now I am going to create a harness to go from the neutral safety switch on the AOD to the main harness... it may not be as clean but it is certainly much safer.

It makes me wonder what was going on at Ford - the earlier C4s had the neutral safety switches on the transmission; it seems like they "unlearned" something that could have been a huge liability to them. This has nothing really to do with the fact that I swapped in an AOD; the same problem would be present for a FMX with poorly adjusted linkage. And since the shifter is mounted to the body and the engine and transmission are on rubber mounts that can break it seems fairly probable that the linkage could get bent...

-Rory
 
Glad you averted a disaster! I used the pistol grip shifter out of a '98 Thunderbird for my AOD in the '66. It has the side button for "engaging" 4th o.d. gear but I didn't need that part, just the shifter. I like it for sure and it was cheap at the picknpull. I built a console around it...but I don't have any room for the emergency brake pull type lever on the trans hump now... :cry
 
"gwstang" said:
I used the pistol grip shifter out of a '98 Thunderbird for my AOD in the '66. It has the side button for "engaging" 4th o.d. gear but I didn't need that part, just the shifter. I like it for sure and it was cheap at the picknpull. I built a console around it...but I don't have any room for the emergency brake pull type lever on the trans hump now... :cry

Ummmmmm

:WOP

:ecit
 
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