Thread: AOD tranny swap
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Old 03-29-2004, 04:41 PM
Daniel Jones Daniel Jones is offline
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> 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
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