Glad to help!! n/m

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Posted by Mavman (IP: 216.12.231.242) on May 26, 2000 at 02:38:34:

In Reply to: Re: Auto Tranny Question....something different. posted by Cowboy on May 25, 2000 at 11:23:05:

: : Just needing some assistance with adjusting the bands and whatever in my 72 C4. I'd bring it back to the tranny shop that I had it rebuilt, but it's a good little drive to get there. Any help/suggestions would be greatful!!!

: Thnx for the info mark, copied this from his page. GREAT info!!

: C4 to AOD Transmission Swap (from Dan Jones, m203253@ws2200.mdc.com)

: --------------------------------------------------------------------

: The C4 to AOD Transmission Swap

: or

: How I Spent My 1994 Christmas Vacation

: by Dan Jones

: As promised, I performed the C4 to AOD transmission swap in my parent's 1971

: Mustang convertible. The reason for the transmission swap was to gain the

: benefits of the AOD's 0.675:1 overdrive gear (lower cruise RPM, increased MPG,

: potentially better acceleration). The car in question is powered by a mild

: 302 (600 CFM Holley, dual plane intake, mild cam, dual exhausts) and, before

: the swap, had a perfectly good C4 transmission. While this is essentially a

: bolt in job, there are lots of little details that you should be aware of to

: make things go smoothly. These details, in no particular order, include:

: Procuring the Transmission

: Extension Housing

: Converter Compatibility

: Gear Ratios

: Working with Aluminum

: Transmission Jack and Jackstands

: Transmission Tunnel Clearance

: Exhaust System Clearance

: Transmission Crossmember and Insulator

: Flexplate Diameter and Balance

: Block Plate

: Nuts and Bolts

: Starter

: Driveshaft and Yoke

: Mechanical Interlocks

: Shifter Operation

: Speedometer Gear

: Electrical Connections

: Throttle Valve Operation

: Hydraulic Fittings

: Dipstick Tube

: Drain Plugs

: Transmission Fluid

: Shift Kits and Transmission Coolers

: To give you an idea of what's involved in a swap like this, I've covered my

: experience with each of these details in the paragraphs below. I've also

: listed some comparative weights, dimensions, and gear ratios at the end of

: this posting.

: Procuring the Transmission

: --------------------------

: If you're pulling the AOD from a car, getting all of the related stuff

: (bolts, electrical connector, dipstick tube, converter, yoke, block plate,

: linkages, levers, shifter, hydraulic fittings, etc.), will make life a lot

: easier. However, we used a transmission purchased from a friend of my Dad's

: who rebuilds transmissions. The price was right ($150 rebuilt), but we

: had to come up with all the bits and pieces. Because of the Christmas

: holiday, getting all the right pieces was harder than usual, but we managed.

: Extension Housing

: -----------------

: When purchasing your transmission, be aware that there are two tailshaft

: lengths used on AOD's. The short model is the one that is closest to the C4

: in overall length. I forgot to measure it but the SVO catalog says it's 10.1"

: long. The catalog also indicates the short extension housing AOD was used in

: all passenger cars except rear wheel drive Lincoln Marks and Continentals (not

: sure about the Town Cars), 2WD F-150 trucks built after 11/81, and 83-85 E-150

: vans. Also, don't confuse the AOD with the AOD-E, which uses electronic

: control. There are also extension housing variations among C4's, with a short

: tailshaft model (6 5/8") used on some pickups and vans. Our C4 was the

: standard tailshaft model (13 1/8") that was used in most most applications.

: Converter Compatibility

: -----------------------

: The AOD transmission and torque converter are a matched pair. The AOD uses a

: hollow two piece input shaft (one shaft inside the other) for lock-up purposes

: and requires a specific torque converter. This arrangement is used to bypass

: the converter torque multiplication in higher gears (60% in third and 100% in

: overdrive) for better fuel economy. This is an attractive feature when using

: a high stall speed converter, since locking up the converter eliminates the

: excessive slippage (and the attendant heat generation, RPM rise, and increased

: fuel consumption) associated with such converters. On the down-side, the input

: shaft is weaker than a similarly sized solid one piece design and you lose the

: torque multiplication effect.

: Gear Ratios

: -----------

: The first three gears of the AOD and C4 are of similar ratio. We were looking

: for longer legs and increased fuel economy so we left our rear end gears alone.

: If better acceleration is the goal, a ring and pinion swap may be in order.

: The beauty of this swap is that the AOD's 0.67:1 overdrive ratio can make a

: 3.73:1 ring and pinion act like a cruising 2.50:1 ratio. Come to think of

: it, we've got some extra 3.50:1 gears so maybe I can talk Dad into swapping

: them in.

: Working with Aluminum

: ---------------------

: Like the C6 and C4, the AOD has an aluminum case so use a never-seize

: compound on the aluminum threads (e.g. bolting the the insulator to the case).

: Also, when working with small aluminum threads (e.g. dropping the pan), I

: prefer a beam-type torque wrench so I can tell when I'm approaching the

: desired torque value. I don't trust the click-type wrenches on the little

: stuff.

: Transmission Jack and Jackstands

: --------------------------------

: Despite its aluminum case, the AOD is no lightweight. I measured 150 lbs

: (without fluid or converter - as measured on Mom's bathroom scale) for the

: tranny and 34 lbs for the converter, so a transmission jack is recommended.

: Get the car up in the air as high as possible to give yourself some room to

: maneuver. We used a pair of stacked railroad ties underneath each front tire

: and a pair of tall jackstands under the rear axle housing.

: Transmission Tunnel Clearance

: -----------------------------

: The AOD is beefier around the middle than the C4, so it uses up more space

: in the transmission tunnel. Our '71 Mustang was designed to swallow a C6

: so there was no problem. It might be tight on cars with narrow tunnels

: (like 65-66 Mustangs), but I'm told they will fit with no problem.

: Exhaust System Clearance

: ------------------------

: No problem here on our particular car (dual exhaust without a crossover).

: We could have installed the AOD without ever touching the exhaust, but we

: decided to unbolt the pipes from the exhaust manifolds for extra working

: room. This will vary from car to car so be prepared for potential exhaust

: work. Since I had the pipes unbolted from the manifolds, I took the

: opportunity to put in new exhaust donuts.

: Transmission Crossmember and Insulator

: --------------------------------------

: The only bit of true fabricating that was required for this swap was the

: transmission mount crossmember. While the AOD and C4 overall lengths are

: within a half inch of each other, the mounting pad for the insulator on the

: AOD is 2 inches farther aft, so the crossmember mounting point needs to be

: moved an equal amount. Whether you need to buy or fabricate a custom cross

: member depends on the car you're swapping the transmission into. On some

: full-sized cars, it's supposed to be as easy as switching to a second set of

: aft mounting holes. However, on most of the unibody cars, like Mustangs, a

: custom mount is required. Since I planned to do the swap over Christmas

: break, in another state, and was spending someone else's money, I decided to

: purchase a custom crossmember, rather than fabricate one. I purchased it

: from Auto Creations, a shop that specializes in overdrive transmission swaps

: into older Fords. Besides the mount, they also sell a throttle valve (TV)

: cable kit and can set you up with miscellaneous parts (block plates,

: flexplates, etc.), if you can't get them locally. They also have a list of

: cars from which you can pirate the linkages (ones that came with carbs or

: throttle body injection and AODs). Their mount retains the stock insulator,

: fit as advertised, and was well made. They were also very helpful when I ran

: into problems with the flexplate, taking measurements for me over the phone.

: Even though they were officially closed over the holidays, they stayed in

: phone contact with me to make sure things worked out. If you're contemplating

: this swap, I suggest you give these guys a call. I've included their number

: and address towards the end.

: Flexplate Diameter and Balance

: ------------------------------

: One of the more important parts of the swap is to choose the proper flexplate

: for your application. The integral bellhousing AOD requires a flexplate with

: 164 teeth (approximately 14 1/4" diameter with an 11 7/16" torque converter

: bolt pattern) for proper starter placement and converter compatibility. The

: C4, however, uses a detachable bellhousing that is matched to one of three

: different flexplate sizes (148, 157, and 164 teeth). The 148 teeth flexplates

: are comparatively rare, having been used in cars like the V8 Mustang II. The

: 157 teeth flexplates were generally used in 289/302 small and mid-sized cars,

: while the 164 teeth flexplates were used in 289/302 full-size cars and

: 351W/351C applications. The C4 164 teeth flexplates and the AOD 164 teeth

: flexplates will physically interchange, but there are two balance weights

: (pre-'81 302's use a 28.2 oz-in balance weight, '81-up 5.0 HO's are 50 oz-in),

: to be concerned with. I haven't had a chance to verify but I think all 351W's

: and 351C's used 28.2 oz-in balance factors. Also, the catalog I looked at

: suggested that 1981 and up non-HO 302's are still 28.2 oz-in (at least to

: 1990). Anyone know for sure? In my case, the flexplate in the 1971 Mustang

: came with 157 teeth and a 28.2 oz-in balance factor, so it required replacing.

: Since they both have 164 teeth and 28.2 oz-in balance factors, I was under the

: impression that flexplates from either a 351W w/AOD or early 289/302 w/C4 from

: a full-size car would work. Looking through the books at the parts store

: showed that these were not common part numbers, and listed the 351W part as

: working with an AOT, not AOD, transmission. Not knowing if the AOT indicated

: a subtle variation that I was unaware of, I decided to order the early

: 289/302/C4/full-size part (OEM D1AZ-6375-A, Saginaw XF15). This turned out to

: be a mistake. When we put the converter and transmission up to the engine for

: a fit check, the modeling clay we had put in the crank pilot showed the

: converter snout was barely making contact. Apparently there is a difference

: in flexplate depth. It all would have bolted together and the starter may

: have even managed to reach the flexplate teeth, but there would have been no

: support for the converter and the starter would have eventually chewed up the

: flexplate. Procuring a 351W/AOD flexplate over the holidays turned out to be

: an ordeal (dealers wanted 14 days), but it was required for proper converter

: snout to crank pilot placement, while retaining the proper diameter and

: balance. We finally found a transmission supply house that had the right

: piece. We put the 351W/AOD next to the early 289/302/C4/164 teeth part and

: there was a difference in height. Since then I have checked some aftermarket

: catalogs and they show the same part number for both applications, so buyer

: beware. The part we finally obtained was from Sealed Power and corresponded

: to OEM E0AZ-6375-A (164 teeth flexplate, 28.2 oz-in balance factor, 351W

: with AOD applications). If you're swapping an AOD onto an '81 or later 5.0,

: you'll need the AOD flexplate (164 teeth, 50.0 oz-in balance factor, for 5.0

: with AOD applications). I think the OEM part number for the late 5.0/AOD

: is E2AZ-6375-A, but I didn't verify this. In a pinch, you could swap (weld)

: balance weights between flexplates to get the proper balance factor. If you

: choose to do this, remember that the balance factor is a moment of inertia

: (distance time mass) so keep the product of the distance from the weight to

: the center of the flexplate and the balance weight (plus any additional weld

: weight) equal to a constant (either 28.2 or 50.0 oz-in).

: Block Plate

: -----------

: A block plate (the thin stamped sheet metal plate that fits between the engine

: block and transmission housing) which matches the large AOD bellhousing is

: also required. This plate provides the correct starter location and engagement

: depth for the torque converter snout in the crank pilot (assuming you have the

: right flexplate). We used one from an early 289 full-size application (C4

: with the large bellhousing).

: Nuts and Bolts

: --------------

: The bosses on the AOD bellhousing are thicker than those of the C4, so longer

: bolts are required. We didn't have enough of the proper length (2 1/8 to

: 2 1/4" long bolts), so we cut down a few longer bolts to get the desired

: number of threads. Use a stiff piece of wire as a gauge to make sure they

: don't bottom out. You can re-use the C4 torque converter nuts on the AOD

: converter but it's a good idea to use new ones since these tend to round off.

: Also be aware that the AOD is a mixed standard transmission, despite what the

: METRIC embossed into the pan may imply. Some bolts are metric, others are not.

: Generally, the tranny internals are metric, but the places where the tranny

: connects to the car (insulator, hydraulic fittings, speedo-drive, etc.) are

: not.

: Starter

: -------

: The original starter was retained and aligned properly.

: Driveshaft and Yoke

: -------------------

: When we first put the the yoke into the tranny, it appeared we would need to

: shorten the driveshaft by an inch or so. This was unexpected since the AOD

: is only a 1/2 inch longer than the C4. Upon closer investigation, it became

: apparent the yoke was the problem. We had to trim the C4 yoke to get it to

: fit properly. The AOD yokes must be a bit shorter, so pick one up if you can.

: Mechanical Interlocks

: ---------------------

: The '71 Mustang has a mechanical interlock which locks the shifter into park

: whenever the ignition key is in the lock position. I'm not sure what year

: this first appeared on Fords, but I know my '66 doesn't have it. You could

: bypass the interlock but we kept it functional. This required removing the

: TV/shifter shaft assembly from the AOD (involves dropping the pan and filter).

: Using the original C4 lever as a guide, we cut a spare lever and welded it on

: the shaft. This caused a problem since we were unable to remove the small

: circular grommet that seals the end of the concentric cylinders of the

: TV/shifter shaft assembly without damaging it. The C4 has a rubber O-ring

: in this area but the AOD uses a special formed piece which, like the flexplate,

: wasn't easy to find over the holidays ("Sure we've got one but you'll have to

: buy the $119 rebuild kit to get it").

: Shifter Operation

: -----------------

: We retained the C4 floor mounted shifter in the Mustang. Eyeballing the AOD

: and C4 shift levers, it looked like the hole in the AOD shift lever would need

: to be moved a bit so we welded up hole and drilled a new one. Once everything

: was assembled, we adjusted the linkage to get proper engagement of the gears

: and interlocks, but the pointer was off. It turns out the hole was probably

: in the right spot to begin with. I believe there is a quite a bit of

: variation in Ford shift levers (especially between floor and column mounted

: shifters, but also between body styles), so this will need to be checked on a

: case by case basis.

: Speedometer Gear

: ----------------

: The speedometer driven gear assembly from the '71, including bolt and retaining

: clip, slipped right into the AOD. I didn't get a chance to verify the ratios,

: but the speedometer operated normally. There may be some variation (seven and

: eight teeth gears?) with the AOD drive gear (the gear inside the tailshaft

: housing), so you may have to change driven gears for proper calibration.

: Electrical Connections

: ----------------------

: The AOD uses a four pin electrical connector for the reverse/backup lamps and

: neutral sensing switch. We didn't get one with our tranny, so we soldered

: some wires on and used a liquid rubber compound to insulate. If you end up

: soldering, be careful not to melt the plastic housing that holds the pins in

: place.

: Throttle Valve Operation

: ------------------------

: The AOD does not use engine vacuum and a modulator valve to sense load.

: Instead, a throttle valve is used which moves proportional to throttle pedal

: travel. Unlike a kick-down rod, the TV linkage has to operate throughout the

: full travel. This is one of the most important parts of the swap to get

: right. Failure to do so will cause poor shift quality and can ruin the

: transmission. When adjusting the linkage, it is safer to err on the side of

: hard shifts. There are a several ways of implementing the TV linkage. A rod

: arrangement was used on AOD cars equipped with carbs and TBI while a cable was

: used on SEFI cars. We were planning on getting the linkage off a variable

: venturi (VV) carb from a local junkyard that had a stack of them, but they

: had recently tossed them all out. We ended up adapting the kick down rod to

: serve as the TV linkage. The trick is to ensure the proper range of travel of

: the transmission TV lever for the entire carburetor throttle range. We had

: another AOD equipped car to look at to get the proper lever orientation and

: ratios. You also need a way to adjust the linkage to vary shift feel.

: Alternatively, you could adapt a TV cable from an EFI application or purchase

: one of Auto Creation's TV cable kits. For more information on alternatives, I

: suggest you get a copy of the May 1990 issue of Super Ford magazine. The

: article "A-OK AOD" contains a sidebar on adapting the AOD to non-stock

: applications. Ignore the part about your stock flexplate and block plate

: working just fine and pay close attention to the linkage descriptions.

: Hydraulic Fittings

: ------------------

: The hydraulic fittings on our AOD were larger than those of the previous C4.

: After the existing lines were trimmed to their proper length, two adapter

: fittings (1/4" (ID) pipe, 5/16" (OD) tubing) were used to mate the fittings

: on the transmission lines to the AOD case. I believe the lines on our car

: were not original since they looked like new and had quite a bit of excess

: length. They were also harder than any factory line I've dealt with. Even

: though we used the proper tubing benders and double flair tools, the lines

: were very hard to work with.

: Dipstick Tube

: -------------

: With a minor bending of the the attachment bracket, the AOD dipstick tube went

: in easily. The AOD tube proved to be shorter than the C4 tube and ended up in

: close proximity to the export brace, so a long neck funnel was required to fill

: the transmission. Of course, this will vary from car to car.

: Drain Plugs

: -----------

: One thing I forgot to do was to install a drain plug kit when I had the pan

: off. B&M makes an inexpensive kit that, along with our stock converter's

: drain plug, would make it very easy to do complete fluid changes.

: Transmission Fluid

: ------------------

: AOD's take a lot of Dextron-II transmission fluid (the C4 used type F). The

: Chilton's we checked for capacities quoted 24 pints (12 quarts) for a totally

: dry transmission like ours.

: Shift Kits and Transmission Coolers

: -----------------------------------

: This particular car is not subjected to much abuse so we didn't install a

: shift kit or auxiliary transmission cooler. To begin with, we'll simply

: adjust the TV linkage to give firmer shifts and see how it works out.

: For performance applications, the guys at Auto Creations recommend a Karl

: Baumann shift kit and the Thunderbird C-servo upgrade. Because we might be

: putting an AOD behind my brother's 351W and a friend's 351C-2V, I did some

: research on AOD durability and performance modifications. There are several

: things that should be done to an AOD, if you want it to live behind a high

: performance engine. It may be several weeks before I can get to it, but I'll

: try to post a summary of my findings.

: Unfortunately, I haven't had a chance to drive the car yet, since I had to get

: back to St. Louis. I left the car up on jackstands, with the wheels spinning

: in all gears. I'll get some time behind the wheel the next time I'm in Ohio.

: While there are lots of little details (and a couple major ones), this is

: definitely a do-able swap, especially if you get all the related parts from

: the same car. I've included all the variations that I am aware of, but

: remember YMMV. As a reference, I've included some comparative C4 and AOD

: dimensions and weights, plus a bunch of gear ratios. Email me with any

: corrections or additions you may have. Also, before I sign off, allow me to

: thank all of you who responded to my request for AOD information.

: Cheers,

: Dan Jones

: m203253@ws2200.mdc.com

: P.S.

: I'm going to send a copy of this posting to Auto Creations and ask them for

: any input they might have. I'll post any additional info at a later date.

: Based upon my positive experience with them, I'm going to work with them on

: a couple of other swaps in the future. When I mentioned I was going to post

: this write-up to the list, they said they'd give me a break on prices for any

: referrals so tell Dave I sent you. They can be contacted at:

: Auto Creations

: 19201 Meadowvale Rd.

: Elk River, Mn 55330

: (612) 441-5567

: C4 and AOD Dimensions

: ---------------------

: Overall Length (bellhousing to tailshaft housing end, flat-to-flat):

: AOD - 30 3/4"

: C4 - 30 1/4"

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Comments:
: : : Just needing some assistance with adjusting the bands and whatever in my 72 C4. I'd bring it back to the tranny shop that I had it rebuilt, but it's a good little drive to get there. Any help/suggestions would be greatful!!! : : Thnx for the info mark, copied this from his page. GREAT info!! : : : C4 to AOD Transmission Swap (from Dan Jones, m203253@ws2200.mdc.com) : : -------------------------------------------------------------------- : : The C4 to AOD Transmission Swap : : or : : How I Spent My 1994 Christmas Vacation : : by Dan Jones : : : As promised, I performed the C4 to AOD transmission swap in my parent's 1971 : : Mustang convertible. The reason for the transmission swap was to gain the : : benefits of the AOD's 0.675:1 overdrive gear (lower cruise RPM, increased MPG, : : potentially better acceleration). The car in question is powered by a mild : : 302 (600 CFM Holley, dual plane intake, mild cam, dual exhausts) and, before : : the swap, had a perfectly good C4 transmission. While this is essentially a : : bolt in job, there are lots of little details that you should be aware of to : : make things go smoothly. These details, in no particular order, include: : : : Procuring the Transmission : : Extension Housing : : Converter Compatibility : : Gear Ratios : : Working with Aluminum : : Transmission Jack and Jackstands : : Transmission Tunnel Clearance : : Exhaust System Clearance : : Transmission Crossmember and Insulator : : Flexplate Diameter and Balance : : Block Plate : : Nuts and Bolts : : Starter : : Driveshaft and Yoke : : Mechanical Interlocks : : Shifter Operation : : Speedometer Gear : : Electrical Connections : : Throttle Valve Operation : : Hydraulic Fittings : : Dipstick Tube : : Drain Plugs : : Transmission Fluid : : Shift Kits and Transmission Coolers : : : To give you an idea of what's involved in a swap like this, I've covered my : : experience with each of these details in the paragraphs below. I've also : : listed some comparative weights, dimensions, and gear ratios at the end of : : this posting. : : : Procuring the Transmission : : -------------------------- : : If you're pulling the AOD from a car, getting all of the related stuff : : (bolts, electrical connector, dipstick tube, converter, yoke, block plate, : : linkages, levers, shifter, hydraulic fittings, etc.), will make life a lot : : easier. However, we used a transmission purchased from a friend of my Dad's : : who rebuilds transmissions. The price was right ($150 rebuilt), but we : : had to come up with all the bits and pieces. Because of the Christmas : : holiday, getting all the right pieces was harder than usual, but we managed. : : : Extension Housing : : ----------------- : : When purchasing your transmission, be aware that there are two tailshaft : : lengths used on AOD's. The short model is the one that is closest to the C4 : : in overall length. I forgot to measure it but the SVO catalog says it's 10.1" : : long. The catalog also indicates the short extension housing AOD was used in : : all passenger cars except rear wheel drive Lincoln Marks and Continentals (not : : sure about the Town Cars), 2WD F-150 trucks built after 11/81, and 83-85 E-150 : : vans. Also, don't confuse the AOD with the AOD-E, which uses electronic : : control. There are also extension housing variations among C4's, with a short : : tailshaft model (6 5/8") used on some pickups and vans. Our C4 was the : : standard tailshaft model (13 1/8") that was used in most most applications. : : : Converter Compatibility : : ----------------------- : : The AOD transmission and torque converter are a matched pair. The AOD uses a : : hollow two piece input shaft (one shaft inside the other) for lock-up purposes : : and requires a specific torque converter. This arrangement is used to bypass : : the converter torque multiplication in higher gears (60% in third and 100% in : : overdrive) for better fuel economy. This is an attractive feature when using : : a high stall speed converter, since locking up the converter eliminates the : : excessive slippage (and the attendant heat generation, RPM rise, and increased : : fuel consumption) associated with such converters. On the down-side, the input : : shaft is weaker than a similarly sized solid one piece design and you lose the : : torque multiplication effect. : : : Gear Ratios : : ----------- : : The first three gears of the AOD and C4 are of similar ratio. We were looking : : for longer legs and increased fuel economy so we left our rear end gears alone. : : If better acceleration is the goal, a ring and pinion swap may be in order. : : The beauty of this swap is that the AOD's 0.67:1 overdrive ratio can make a : : 3.73:1 ring and pinion act like a cruising 2.50:1 ratio. Come to think of : : it, we've got some extra 3.50:1 gears so maybe I can talk Dad into swapping : : them in. : : : Working with Aluminum : : --------------------- : : Like the C6 and C4, the AOD has an aluminum case so use a never-seize : : compound on the aluminum threads (e.g. bolting the the insulator to the case). : : Also, when working with small aluminum threads (e.g. dropping the pan), I : : prefer a beam-type torque wrench so I can tell when I'm approaching the : : desired torque value. I don't trust the click-type wrenches on the little : : stuff. : : : Transmission Jack and Jackstands : : -------------------------------- : : Despite its aluminum case, the AOD is no lightweight. I measured 150 lbs : : (without fluid or converter - as measured on Mom's bathroom scale) for the : : tranny and 34 lbs for the converter, so a transmission jack is recommended. : : Get the car up in the air as high as possible to give yourself some room to : : maneuver. We used a pair of stacked railroad ties underneath each front tire : : and a pair of tall jackstands under the rear axle housing. : : : Transmission Tunnel Clearance : : ----------------------------- : : The AOD is beefier around the middle than the C4, so it uses up more space : : in the transmission tunnel. Our '71 Mustang was designed to swallow a C6 : : so there was no problem. It might be tight on cars with narrow tunnels : : (like 65-66 Mustangs), but I'm told they will fit with no problem. : : : Exhaust System Clearance : : ------------------------ : : No problem here on our particular car (dual exhaust without a crossover). : : We could have installed the AOD without ever touching the exhaust, but we : : decided to unbolt the pipes from the exhaust manifolds for extra working : : room. This will vary from car to car so be prepared for potential exhaust : : work. Since I had the pipes unbolted from the manifolds, I took the : : opportunity to put in new exhaust donuts. : : : Transmission Crossmember and Insulator : : -------------------------------------- : : The only bit of true fabricating that was required for this swap was the : : transmission mount crossmember. While the AOD and C4 overall lengths are : : within a half inch of each other, the mounting pad for the insulator on the : : AOD is 2 inches farther aft, so the crossmember mounting point needs to be : : moved an equal amount. Whether you need to buy or fabricate a custom cross : : member depends on the car you're swapping the transmission into. On some : : full-sized cars, it's supposed to be as easy as switching to a second set of : : aft mounting holes. However, on most of the unibody cars, like Mustangs, a : : custom mount is required. Since I planned to do the swap over Christmas : : break, in another state, and was spending someone else's money, I decided to : : purchase a custom crossmember, rather than fabricate one. I purchased it : : from Auto Creations, a shop that specializes in overdrive transmission swaps : : into older Fords. Besides the mount, they also sell a throttle valve (TV) : : cable kit and can set you up with miscellaneous parts (block plates, : : flexplates, etc.), if you can't get them locally. They also have a list of : : cars from which you can pirate the linkages (ones that came with carbs or : : throttle body injection and AODs). Their mount retains the stock insulator, : : fit as advertised, and was well made. They were also very helpful when I ran : : into problems with the flexplate, taking measurements for me over the phone. : : Even though they were officially closed over the holidays, they stayed in : : phone contact with me to make sure things worked out. If you're contemplating : : this swap, I suggest you give these guys a call. I've included their number : : and address towards the end. : : : Flexplate Diameter and Balance : : ------------------------------ : : One of the more important parts of the swap is to choose the proper flexplate : : for your application. The integral bellhousing AOD requires a flexplate with : : 164 teeth (approximately 14 1/4" diameter with an 11 7/16" torque converter : : bolt pattern) for proper starter placement and converter compatibility. The : : C4, however, uses a detachable bellhousing that is matched to one of three : : different flexplate sizes (148, 157, and 164 teeth). The 148 teeth flexplates : : are comparatively rare, having been used in cars like the V8 Mustang II. The : : 157 teeth flexplates were generally used in 289/302 small and mid-sized cars, : : while the 164 teeth flexplates were used in 289/302 full-size cars and : : 351W/351C applications. The C4 164 teeth flexplates and the AOD 164 teeth : : flexplates will physically interchange, but there are two balance weights : : (pre-'81 302's use a 28.2 oz-in balance weight, '81-up 5.0 HO's are 50 oz-in), : : to be concerned with. I haven't had a chance to verify but I think all 351W's : : and 351C's used 28.2 oz-in balance factors. Also, the catalog I looked at : : suggested that 1981 and up non-HO 302's are still 28.2 oz-in (at least to : : 1990). Anyone know for sure? In my case, the flexplate in the 1971 Mustang : : came with 157 teeth and a 28.2 oz-in balance factor, so it required replacing. : : Since they both have 164 teeth and 28.2 oz-in balance factors, I was under the : : impression that flexplates from either a 351W w/AOD or early 289/302 w/C4 from : : a full-size car would work. Looking through the books at the parts store : : showed that these were not common part numbers, and listed the 351W part as : : working with an AOT, not AOD, transmission. Not knowing if the AOT indicated : : a subtle variation that I was unaware of, I decided to order the early : : 289/302/C4/full-size part (OEM D1AZ-6375-A, Saginaw XF15). This turned out to : : be a mistake. When we put the converter and transmission up to the engine for : : a fit check, the modeling clay we had put in the crank pilot showed the : : converter snout was barely making contact. Apparently there is a difference : : in flexplate depth. It all would have bolted together and the starter may : : have even managed to reach the flexplate teeth, but there would have been no : : support for the converter and the starter would have eventually chewed up the : : flexplate. Procuring a 351W/AOD flexplate over the holidays turned out to be : : an ordeal (dealers wanted 14 days), but it was required for proper converter : : snout to crank pilot placement, while retaining the proper diameter and : : balance. We finally found a transmission supply house that had the right : : piece. We put the 351W/AOD next to the early 289/302/C4/164 teeth part and : : there was a difference in height. Since then I have checked some aftermarket : : catalogs and they show the same part number for both applications, so buyer : : beware. The part we finally obtained was from Sealed Power and corresponded : : to OEM E0AZ-6375-A (164 teeth flexplate, 28.2 oz-in balance factor, 351W : : with AOD applications). If you're swapping an AOD onto an '81 or later 5.0, : : you'll need the AOD flexplate (164 teeth, 50.0 oz-in balance factor, for 5.0 : : with AOD applications). I think the OEM part number for the late 5.0/AOD : : is E2AZ-6375-A, but I didn't verify this. In a pinch, you could swap (weld) : : balance weights between flexplates to get the proper balance factor. If you : : choose to do this, remember that the balance factor is a moment of inertia : : (distance time mass) so keep the product of the distance from the weight to : : the center of the flexplate and the balance weight (plus any additional weld : : weight) equal to a constant (either 28.2 or 50.0 oz-in). : : : Block Plate : : ----------- : : A block plate (the thin stamped sheet metal plate that fits between the engine : : block and transmission housing) which matches the large AOD bellhousing is : : also required. This plate provides the correct starter location and engagement : : depth for the torque converter snout in the crank pilot (assuming you have the : : right flexplate). We used one from an early 289 full-size application (C4 : : with the large bellhousing). : : : Nuts and Bolts : : -------------- : : The bosses on the AOD bellhousing are thicker than those of the C4, so longer : : bolts are required. We didn't have enough of the proper length (2 1/8 to : : 2 1/4" long bolts), so we cut down a few longer bolts to get the desired : : number of threads. Use a stiff piece of wire as a gauge to make sure they : : don't bottom out. You can re-use the C4 torque converter nuts on the AOD : : converter but it's a good idea to use new ones since these tend to round off. : : Also be aware that the AOD is a mixed standard transmission, despite what the : : METRIC embossed into the pan may imply. Some bolts are metric, others are not. : : Generally, the tranny internals are metric, but the places where the tranny : : connects to the car (insulator, hydraulic fittings, speedo-drive, etc.) are : : not. : : : Starter : : ------- : : The original starter was retained and aligned properly. : : Driveshaft and Yoke : : ------------------- : : When we first put the the yoke into the tranny, it appeared we would need to : : shorten the driveshaft by an inch or so. This was unexpected since the AOD : : is only a 1/2 inch longer than the C4. Upon closer investigation, it became : : apparent the yoke was the problem. We had to trim the C4 yoke to get it to : : fit properly. The AOD yokes must be a bit shorter, so pick one up if you can. : : : Mechanical Interlocks : : --------------------- : : The '71 Mustang has a mechanical interlock which locks the shifter into park : : whenever the ignition key is in the lock position. I'm not sure what year : : this first appeared on Fords, but I know my '66 doesn't have it. You could : : bypass the interlock but we kept it functional. This required removing the : : TV/shifter shaft assembly from the AOD (involves dropping the pan and filter). : : Using the original C4 lever as a guide, we cut a spare lever and welded it on : : the shaft. This caused a problem since we were unable to remove the small : : circular grommet that seals the end of the concentric cylinders of the : : TV/shifter shaft assembly without damaging it. The C4 has a rubber O-ring : : in this area but the AOD uses a special formed piece which, like the flexplate, : : wasn't easy to find over the holidays ("Sure we've got one but you'll have to : : buy the $119 rebuild kit to get it"). : : : Shifter Operation : : ----------------- : : We retained the C4 floor mounted shifter in the Mustang. Eyeballing the AOD : : and C4 shift levers, it looked like the hole in the AOD shift lever would need : : to be moved a bit so we welded up hole and drilled a new one. Once everything : : was assembled, we adjusted the linkage to get proper engagement of the gears : : and interlocks, but the pointer was off. It turns out the hole was probably : : in the right spot to begin with. I believe there is a quite a bit of : : variation in Ford shift levers (especially between floor and column mounted : : shifters, but also between body styles), so this will need to be checked on a : : case by case basis. : : : Speedometer Gear : : ---------------- : : The speedometer driven gear assembly from the '71, including bolt and retaining : : clip, slipped right into the AOD. I didn't get a chance to verify the ratios, : : but the speedometer operated normally. There may be some variation (seven and : : eight teeth gears?) with the AOD drive gear (the gear inside the tailshaft : : housing), so you may have to change driven gears for proper calibration. : : : Electrical Connections : : ---------------------- : : The AOD uses a four pin electrical connector for the reverse/backup lamps and : : neutral sensing switch. We didn't get one with our tranny, so we soldered : : some wires on and used a liquid rubber compound to insulate. If you end up : : soldering, be careful not to melt the plastic housing that holds the pins in : : place. : : : Throttle Valve Operation : : ------------------------ : : The AOD does not use engine vacuum and a modulator valve to sense load. : : Instead, a throttle valve is used which moves proportional to throttle pedal : : travel. Unlike a kick-down rod, the TV linkage has to operate throughout the : : full travel. This is one of the most important parts of the swap to get : : right. Failure to do so will cause poor shift quality and can ruin the : : transmission. When adjusting the linkage, it is safer to err on the side of : : hard shifts. There are a several ways of implementing the TV linkage. A rod : : arrangement was used on AOD cars equipped with carbs and TBI while a cable was : : used on SEFI cars. We were planning on getting the linkage off a variable : : venturi (VV) carb from a local junkyard that had a stack of them, but they : : had recently tossed them all out. We ended up adapting the kick down rod to : : serve as the TV linkage. The trick is to ensure the proper range of travel of : : the transmission TV lever for the entire carburetor throttle range. We had : : another AOD equipped car to look at to get the proper lever orientation and : : ratios. You also need a way to adjust the linkage to vary shift feel. : : Alternatively, you could adapt a TV cable from an EFI application or purchase : : one of Auto Creation's TV cable kits. For more information on alternatives, I : : suggest you get a copy of the May 1990 issue of Super Ford magazine. The : : article "A-OK AOD" contains a sidebar on adapting the AOD to non-stock : : applications. Ignore the part about your stock flexplate and block plate : : working just fine and pay close attention to the linkage descriptions. : : : Hydraulic Fittings : : ------------------ : : The hydraulic fittings on our AOD were larger than those of the previous C4. : : After the existing lines were trimmed to their proper length, two adapter : : fittings (1/4" (ID) pipe, 5/16" (OD) tubing) were used to mate the fittings : : on the transmission lines to the AOD case. I believe the lines on our car : : were not original since they looked like new and had quite a bit of excess : : length. They were also harder than any factory line I've dealt with. Even : : though we used the proper tubing benders and double flair tools, the lines : : were very hard to work with. : : : Dipstick Tube : : ------------- : : With a minor bending of the the attachment bracket, the AOD dipstick tube went : : in easily. The AOD tube proved to be shorter than the C4 tube and ended up in : : close proximity to the export brace, so a long neck funnel was required to fill : : the transmission. Of course, this will vary from car to car. : : : : Drain Plugs : : ----------- : : One thing I forgot to do was to install a drain plug kit when I had the pan : : off. B&M makes an inexpensive kit that, along with our stock converter's : : drain plug, would make it very easy to do complete fluid changes. : : : Transmission Fluid : : ------------------ : : AOD's take a lot of Dextron-II transmission fluid (the C4 used type F). The : : Chilton's we checked for capacities quoted 24 pints (12 quarts) for a totally : : dry transmission like ours. : : : Shift Kits and Transmission Coolers : : ----------------------------------- : : This particular car is not subjected to much abuse so we didn't install a : : shift kit or auxiliary transmission cooler. To begin with, we'll simply : : adjust the TV linkage to give firmer shifts and see how it works out. : : For performance applications, the guys at Auto Creations recommend a Karl : : Baumann shift kit and the Thunderbird C-servo upgrade. Because we might be : : putting an AOD behind my brother's 351W and a friend's 351C-2V, I did some : : research on AOD durability and performance modifications. There are several : : things that should be done to an AOD, if you want it to live behind a high : : performance engine. It may be several weeks before I can get to it, but I'll : : try to post a summary of my findings. : : : : : Unfortunately, I haven't had a chance to drive the car yet, since I had to get : : back to St. Louis. I left the car up on jackstands, with the wheels spinning : : in all gears. I'll get some time behind the wheel the next time I'm in Ohio. : : While there are lots of little details (and a couple major ones), this is : : definitely a do-able swap, especially if you get all the related parts from : : the same car. I've included all the variations that I am aware of, but : : remember YMMV. As a reference, I've included some comparative C4 and AOD : : dimensions and weights, plus a bunch of gear ratios. Email me with any : : corrections or additions you may have. Also, before I sign off, allow me to : : thank all of you who responded to my request for AOD information. : : : Cheers, : : : Dan Jones : : m203253@ws2200.mdc.com : : P.S. : : : I'm going to send a copy of this posting to Auto Creations and ask them for : : any input they might have. I'll post any additional info at a later date. : : Based upon my positive experience with them, I'm going to work with them on : : a couple of other swaps in the future. When I mentioned I was going to post : : this write-up to the list, they said they'd give me a break on prices for any : : referrals so tell Dave I sent you. They can be contacted at: : : : Auto Creations : : 19201 Meadowvale Rd. : : Elk River, Mn 55330 : : (612) 441-5567 : : C4 and AOD Dimensions : : --------------------- : : : Overall Length (bellhousing to tailshaft housing end, flat-to-flat): : : AOD - 30 3/4" : : C4 - 30 1/4"

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