Hey guys I have a 69 Mach with a 1973 351C. I would l like to switch out the FMX to a AOD transmission. What transmission is the best fit? What will I have to change?

 

I'm not sure what you'll want or need to upgrade internally to cope with a 351C.

But you will want an AOD as opposed to an AODE (electronic), and I can tell you that getting the TV cable installed and adjusted properly takes absolute priority over things like exhaust pipe routing.

Some years ago I swapped an AOD into a '66 (and somebody I know did a similar swap with a lot less success), and I still remember a few of the details ;=)


Norm

 

Mmmm... It's early and I'm forgetting more than I remember, but here's a few details popping into my head. You need an AOD from around 89-90 or later, not earlier due to improvements. You'll need to shorten your driveshaft, modify your rear crossmember or replace it as the rear mount is further back, modify the shift linkage, install a Lokar TV cable set that MUST be adjusted properly. Many folks get scared and over react to this adjustment. The simple Ford way of adjusting it was no slack, not tension at idle. Works fine. The better way is just off zero psi using a gauge. The Lokar kit explains it. Many claim improper adjustment will burn it up in a heartbeat, and this is true, but that's a case of being WAY off, not a few psi. The no slack/no tension production method was the way a few hundred thousand left the Ford plant.

Also, be educated going into this that it's NOT a lockup type converter/transmission. Third and 4th are direct drive due to a separate input which is the same as "locked up", but this isn't a selectable shift as in other transmissions. That just needs clarification before someone else comes in and screws up a whole thread with the wrong info...

 

This guy sells a conversion kit that has just about everything you need. The only other thing I had to buy was a bracket that held the TV cable up top.

http://www.transmissioncenter.org/cl...conversion.htm

 

I have an AOD in my car. Highway gas mileage went from 15 mpg to 20. I have a 3.25 rear end so it cruises at 70 mph at 2000 rpm. Paid for itself.

I didn't have to shorten my driveshaft. I found a shorter yolk and it fixed the problem. Also had to run a stock cast iron header from a mid 70s van on the right side to clear the transmission bulge.

 

Nah you'll want a 4R70W instead of an AOD, then you don't have to worry about the TV cable If you don't want to deal with a Bauman controller you'll want to take the stronger gear set from the 4R70W and put it into an AOD. I'm putting a 4R70W into my 66, it's not a big deal. You have to be careful with headers, not all will clear the wider case. The overall length of an AOD should be very close so you may have to do nothing with the drive shaft or at a most find shorter yoke. There are kits available for this. With a 4R70W you have to shorten the drive shaft and install a new cross member. AOD conversion is easy, 4R70W while also easy does require a little more thought. There is a TON of information on AOD conversions with many step by step threads, google will be your friend. 4R70W conversions not so much but there is still some decent info available. Definitely gets more difficult in smaller cars like my 66.
I went with the 4R70W because I want the controller, I can change the characteristics of the car from a mild street performer, to a track car, to a drag car with a simple download from my laptop. I don't have to worry about setting up my car for single use like I would with a valve body.

 

Either way sounds better strengthwise for a 351C today, but that wasn't an option at the time I was going through this sort of swap (early April of 1994). The AOD in my case only had to put up with a stockish 302, and the car was my daughter's anyway (if it'd been one of mine it'd have got a T5 and a clutch instead).


I got away with modifying the crossmember using 1/8" thick steel strips and there seemed to be plenty of room for a fabbed up a set of duals back from the iron manifolds, but I don't remember anything either way concerning the driveshaft. There was some sort of tinkering required with respect to the P-brake mechanism, which may or may not be an issue with sisco's '69. And a bit more getting the OE 3-speed shifter to work with it (don't remember much here, except that I didn't buy anything).


Norm

 

Yep, forgot that part. I used Doug Thorely headers which didn't fit with the trans bell housing, and I just ground a couple of areas with room to spare. Some claim to have issues with the headers hitting the trans pan so you might look into that, but it didn't apply to mine with the DG headers.

 

My headers cleared the bell housing just fine, but the flanges touched the edges of the transmission pan (both sides). Of course, one side was exactly where the TV cable bracket was supposed to mount to the transmission pan. I had to have the flanges cut off and a pipe welded in to connect the headers to the exhaust pipes. On the bright side - I don't have to worry about that connection leaking.

 

351c Headers from www.fordpowertrain.com will clear the trans no problem.