AOD tranny swap
 

I am currently running a C-4 behind a 351W with 3.5:1 rear gears. Rather than swapping out the rear gears to improve highway mileage I am considering going to an AOD and I have a few questions.

1. What are the advantages/disadvantages of using an AOD lock up as opposed to a non-lock up?

2. Will the trans crossmember have to be moved or modified to accept the AOD?

3. How easy is it to attach the AOD TV cable to a Holley 600 carb?

4. Can I use the B&M Hammer shifter that I currently use or will I have to go to a different shifter? Any modifications or adaptors needed?

Any help or advice would be greatly appreciated.

Tony

hey tony
i've had an aod in my cobra since day one. my reason for using the aod was at the time three operations on my left knee-one since- and i didn't want to worry about trying to shift. it took me three years to sort out all of the problems and get the tranny to work properly. the aod is quite a bit larger than your c-6, although a friend told me that they make a smaller version now. the lock up verses non lock up would depend on what you plan to do with the car. non lock up is easier driveability. the cross member would have to change. you would use a cable to work the tv lever. as for the shifter, i don't think you shoud have any problem hooking it up. i'm using a b-m ratchet type shifter. there are several companies that make aod's. stay away from the electric models. you can have it built to your specs. i bought a used one and had it built to my specs locally by a friend that builds race trannys. to make sure you don't have problems and burn up the tranny you need to have the proper pressure from the tv cable. if you do decide to go this route i'll be happy to offer any help you need. by the way, i have 4:10 gears and can cruise at around 2400 rpm!
paul

Hey Tony
 

I am forwarding an email I receieved from someone who put an AOD in their Cobra. I am contemplating doing the same thing to mine.

Hi Scott

Love that AOD.....best thing I ever did.....but I have to listen to all
those guys at Unique giving me the gears....Bottom line...I gotta drive
it...I gotta enjoy it.....and enjoy it I do.

The AOD came out of a 1980 Mercury Marquis.....complete with the first
engine I put in the Cobra....I was on very tight budget at the time with 3
growing kids having greater needs than the car.
The car cost me $400.00.....transplanted the engine and the AOD straight
into the Cobra.....towed the rest to the junk yard, took off the alloy
whells....sold them for $100.....now have Corbra with complete powertrain
for $300.00.
Of course all worked well as I used the original carb. and linkage.....I
even wired up the 'park' location cut out on the ignition circuit...I used a
sawn off B&M shifter...cut down to 7 inches high...the cable routing comes
to the box from the rear and was a breeze with all the different brackets
B&M supply with their shifter kits.

The AOD , over a period of time got a bit slussy.....not to bad........Then
I had some engine problems.....no sweat.
Took it all out and put in an engine and tranny from a 1986 pick up
truck...this had a C4.
I dumped the old engine BUT kept the AOD.
The C4 did not work for me.....to high in the rev range at cruising
speed....I was used to the low revs when the 4th speed dropped in on the
AOD.
So I had the AOD refurbished and had a simple shift kit put in it just to
firm up the 3/4 change up......Put it back in...dumped the C4........Now I'm
really happy again.
So to answer your question, I would consider the AOD to be stock.
There were NO snags puttting it in....the drive shaft is the same length for
a C4, the splines are the same.
The AOD is actually a very workable solution for a Unique Cobra....it fits
very easily in the tunnel...plenty of room to hook up shift cables and
speedo cables.
By dropping the transmission mount, the box will angle down enough on the
engine mounts that it can be removed real easy.

The Holly hoook ups.....I am certain that I've seen Holly carbs in both the
JEGS and SUMMIT catalogues where they sell a special bracket ( $10 to $15 )
to hook Holly's and Elderbocks up to AOD's.

The only way I can hold the shift on the AOD is either in D1 or D2....the
push it up to the 'D' postion where the 3rd and 4th gears take over.

The good thing about the earlier AOD's is that there are absolutely NO
electronics associated with them....its a lovely manual affair.

I don't care what other 'Cobra' people think about auto. boxes.......I love
mine and will NEVER change to a Manual box.

If there's anything else i can tell you ., please drop me a line.

Enjoy that auto box.........................Mike

> 1. What are the advantages/disadvantages of using an AOD lock up as opposed
> to a non-lock up?

The lock up gives better fuel economy, a lower cruise RPM, and probably
runs a bit cooler. You can also run a little higher stall speed convertor
with the lock-up than you might otherwise, as the slippage goes away upon
lock-up. The biggest downside is that the input shaft is not solid and
is therefore weaker. The lock-up uses a solid shaft within a hollow shaft
that can break if you have enough torque and traction.

> Will the trans crossmember have to be moved or modified to accept the AOD?

Yes. The mount is farther aft. Dimensions in the attached post.

> 3. How easy is it to attach the AOD TV cable to a Holley 600 carb?

You'll need a special bracket and throttle valve cable. You can also
adapt the linkage from the donor car. If you can find an old variable
venturi carb car with AOD, you can rob that set-up. If your time is
worth much, there are kits ready made for the purpose.

> the aod is quite a bit larger than your C-4, although a friend told me
> that they make a smaller version now.

There are length variations to be aware of. I've done the AOD swap a couple
of times and the second time I used a Licoln Town AOD. Turns out the
Town Car tailshaft housing was about 3/4" longer than the Mustang AOD I'd
used previously. The rear mount is in the same place, so the only impact
is on the length of the driveshaft.

> stay away from the electric models.

The AOD-E is an electric valve body version of the AOD and requires a
computer for control. Karl Baumann makes a stand-alone computer for
that purpose if not running a Ford EEC-IV or EEC-V. The AOD_E recieved
a number of heavy duty upgrades, so is worthy of consideration. Also,
no TV cable problems.

> The Holly hoook ups.....I am certain that I've seen Holly carbs in both
> the JEGS and SUMMIT catalogues where they sell a special bracket ( $10
> to $15 ) to hook Holly's and Elderbocks up to AOD's.

I think you're confusing the Ford kickdown linkage brackets. The AOD's
don't use that. They use a throttle valve which requires a different
set-up (available from several places including Windsor-Fox and Total
Performance) and are closer to $75 than $15. Be aware the throttle valve
adjustment is critical. It's better to start with the shifts on the hard
side, rather than the soft side as the slippage in a soft shift can cause
trouble. I tried to adapt a kickdown rod arrangement but it never proved
satisfactory. Also, Ford used a rubber grommet at the cable connection.
If that grommet falls out, it can toast the transmission in just a few
miles. That happened to my dad and to a friend's dad. Requires a
complete rebuild.

> Any help or advice would be greatly appreciated.

I tried attaching a detailed write-up I did when I swapped an AOD in place
of a C4 in a 1971 Mustang but it was too long for the forum. An old version
is out on the web at:

http://www.mustangsandmore.com/ubb/D...C4AODswap.html

Your Cobra will be different but the steps to consider are the same.
Don't try to use a 5.0L flex plate, as the balance will be wrong:

Balance Factor Information
--------------------------

1981-and-up 5.0L - 50.0 oz-in
Pre-1981 289/302 - 28.2 oz-in
351W and 351C-400 - 28.2 oz-in

Also, the pin wiring sequence is:

4 Pin Wiring Sequence (AOD)
---------------------------

#33 W/PK (AOD Neutral safety)
#32 R/LB (AOD Neutral safety)
#140 BK/PK (AOD Back-up lights)
#298 P/O (AOD Back-up lights)

Dan Jones

Tony - Been down this road. You might look at the C6 thread by Keane in the 429/460 engine talk section of Club Cobra. In my eyes you've already got the best core there is for a rebuild, with that C4 together on a Cobra. My advice to you is to think small, not bigger. MUCH smarter that way.
cobrashock

Here's what you need for the holley.
 

I just put an AOD in my dad's '67 galaxie. The advice you've gotten so far is great, tv cable setting is critical, in my case I wanted about 1/8" more pulled out than slack. Be sure before you drive the car you have no slack at least (and do this after you have adjusted your idle speed). I bought a lentech valve body and non-lockup converter (lentech recommended) and have been real satisfied with them.

Ford Tranny Talk Had This Thread.

I used the Lokar TV cable setup but that didn't have the correct geometry with the Holley Carb.

Then from Sonnax.com get the following parts;

The Sonnax Holley lever is p/n: AS2-02K
The TV cable corrector is p/n: AS1-01K

Once you have those parts in place you can use wide open throttle as your baseline for the TV cable, you may want to go a little tighter than that even.


You can order the sonnax parts online here

Also my AOD was an '85 from a T-bird and it did not require shortening the drive shaft at all. All I did for mount was reverse the factory mount, I have no idea on yours. Most likely yours will have to move back an inch or two.


Good luck, Chuck