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4R70W AOD Swap Details

59K views 79 replies 18 participants last post by  AndyM 
#1 · (Edited by Moderator)
Here is a summary for those of you considering an AOD. I was initially set on a early non-electric AOD, but quickly decided against it after learning about the benefits of the 4R70W.

4R70W Swap Introduction:
-Updated 3/3/2011

The following is a summary of the installation of a 4R70W into my 1967 Cougar. I was initially set on an early non-electric AOD. After doing some research, I came to the conclusion that early AODs have many weak points. Rebuilt “bulletproof” AODs are available with upgraded parts, but they are very expensive. I was initially looking at a $1,800 rebuilt early AOD. The transmission I was interested in had a wide ratio gear set from a 4R70W. This single upgrade was $300.

I decided to research other, more affordable options. I came across a post discussing the 4R70W transmission. The 4R70W is a computer controlled wide-ratio AOD found in many late model Fords. The wide ratio gearing provides a lower first and second gear to aid in acceleration. Even in its stock form, the 4R70W is a very durable transmission. Unlike the early AOD, the 4R70W already has the good parts.

I was not completely sold on the 4R70W due to the expensive electronics, limited information about the swap, and nonexistent conversion parts. I decided to pursue the 4R70W further after talking to Joe Persad, a member of the All Ford Mustang forum. Joe had already completed the 4R70W swap, and offered to reproduce the conversion parts. I was completely sold after finding many low mile local transmissions for next to nothing. I ended up purchasing a low mile 2002 3.8L 4R70W with torque converter for $200. The transmission even had a 1-year warranty. Keep in mind I was quoted $300 to upgrade a early AOD to wide ratio gearing, and here I purchased an entire wide-ratio transmission/torque converter for $200.

Additional information:
http://www.becontrols.com/tech/tech.htm
http://www.becontrols.com/tech/ch4usedtrans.htm
http://tccoa.com/articles/tranny/index.html

Transmission:
-The conversion requires a 4R70W from a late model 3.8L, 4.2L, 5.0L vehicle.
-1998+ 4R70Ws are recommended due to several mechanical improvements.
-Compatible 4R70Ws are identified by a 2 bolt starter flange. This version will have the proper bolt pattern for small block 289, 302, and 351. See the links above for more information.
-The 3.8L version has one less clutch plate than the 4.2L/5.0L unit. Therefore, the 4.2L/5.0L unit is preferred for high performance engines. However, the 3.8L V6 version is generally less expensive, and easier to find with low miles. Also, the 3.8L version can be upgraded with an extra clutch plate if desired. My research suggests that unlike the early AODs, the V6 4R70W need not be avoided.
-2003 and newer models do not have teeth on the output shaft. Therefore, they cannot support a mechanical speedometer.

Yoke/Driveshaft:
The 4R70W extension housing only accepts a 4R70W slip yoke due to the larger output bushing. You can swap extension housings in order to use a smaller C4, early AOD, or T5 slip yoke. I decided to keep the extension housing and use a 4R70W yoke from a 2002 Crown Victoria P71. The driveshaft had to be shortened to 52” due to the extra length of the AOD.

Flywheel, Block Plate, Starter:
I had to install a larger 164 tooth 28 oz flywheel. I also needed a new block/ inspection plate. These parts were necessary because my previous trans was a small bell housing C4. You may already have the proper parts depending on your application. My aftermarket mini-starter easily bolted to the AOD without any problems.

Cooling lines:
One of the stock cooling lines had to be modified (shortened and bent) to fit the 4R70W. The other line fit fine without modifications. It is highly recommended that you install an aftermarket plate type transmission cooler. I installed a B&M super cooler with braided steel lines.

Torque Converter:
I used the stock 3.8L torque converter. According to my Ford Shop CD, it has a stall speed of 2,207-2,590. Now, I am not sure how Ford determined this number. It is likely calculated as connected to a 3.8L engine.

Transmission Cross Member:
Due to the extra length of the AOD, the C4 cross member cannot be used. I purchased my cross member from Joe Persad, "silver69" from the All Ford Mustang Forum, joepersad@aol.com
Side note, the C4 rubber transmission mount worked fine with the aftermarket cross member.

Electronics:
http://www.becontrols.com

I purchased a Baumann TCS to control the transmission. The TCS allows you to modify the trans shift pattern (and a whole lot more) with a laptop. Pretty cool! The wiring is straight forward with the Baumann full harness. Details are available on the Baumann website. You will also need to install a Throttle Position Sensor (TPS). This takes the place of the TV cable found on early AODs. There are several TPS options. I went with a Holley TPS from Summit Racing. This is the easiest route and bolts right up to most Holley carburetors.

Shifter:
The 4R70W originally had a cable shifter linkage. I decided to use a conventional shifter rod at the recommendation of Joe Persad. Joe was in the process of making the shifter components, but the parts were not quite ready when I required them. As a result, I fabricated my own range sensor bracket and shifter rod based on his photos. I used components from a Lokar Column Shift Linkage. Several modifications to the range sensor are required to use a shifter rod. See my Picasa gallery for more information. The shifter rod and range sensor bracket are now available from Joe Persad, "silver69" from the All Ford Mustang Forum, joepersad@aol.com

Exhaust:
The 4R70W is much larger than the C4. As a result, the stock exhaust pipes did not clear the 4R70W. Modifying the H-pipe section would likely provide enough room. The clearance problem gave me an excuse to upgrade to a complete Magnaflow stainless exhaust (and coated headers too). A full exhaust replacement was not necessary by any means, and will not be included in the cost of the conversion. I would recommend having a muffler shop tweak your existing setup.

Speedometer:
I changed the plastic speedometer gear as the speedometer was not accurate. This was due to different number of teeth on the 4R70W output shaft (in comparison to the C4). Again, 2002 is the last year which supports a mechanically driven speedometer.

Other Transmission Modifications:
-There are two machining locators on the top of the trans case toward the rear. They can cause possible clearance issues and should be cut off.
-The filler tube will require minor bending to fit.
-New longer bolts are required to bolt the trans to the motor.

Optional:
-I performed the “J-Mod” which is a shift kit created by Jerry, one of the engineers who designed the 4R70W. The J-Mod includes removing two springs and enlarging several holes in the separator plate. I ended up reinstalling the lower accumulator spring as the 1-2 shift was far too aggressive. I do not recommend the J-Mod unless you like very aggressive shifts.
-I installed a deep, extra capacity TCI pan.

Cost breakdown:
Baumann Controller and Full Harness $550.00
4R70W $200.00
P71 Yoke $40.00
Driveshaft Shortening $90.00
Hawks Racing flywheel $59.99
B&M aluminum plate cooler $58.25
Holley TPS $99.95
Block plates $28.50
Cross member $99.00
Misc Shifter Linkage Parts $60
Estimated cost to modify stock exhaust $100.00
Total $1,385.69

Again, I am not including the unnecessary items such as the braided cooler lines, TCI pan, or Magnaflow exhaust.
You could save a few bucks by using a trans cooler from a late model F-series truck, fabricating a cross member, and so on...
There is a good chance the entire swap could be done for around $1,000 if you spend your pennies wisely.


Driving Impressions:
As of today (3/3/2011), I have put about 600miles on the transmission. The car gets about 15mpg (3.55 rear), but I think it can achieve 18mpg with a few carburetor adjustments, and a lighter right foot. The car is definitely very fun to drive. I think the wide ratio gearing really helps the little 289 feel powerful. I am very happy with my 4R70W choice!



I hope this information is helpful. Photos are available in my gallery.

Good Luck,
 
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#3 ·
I have a few questions. I did an AOD swap in my '66 mustang that has a 351 Cleveland and i'm planning on replacing that with a T5. So was thinking about putting the aod into my '68 Cougar XR7. But then I read your write up and a few others and was considering upgrading to the 4R70W instead. So I was wondering if certain bits and pieces would be that same for the AOD and the 4R70W such as the driveshaft length, the flywheel, and the block plate?

And one more question. I believe you said that you modified the original shifting rod to work for the 4R70W so I'm guessing you kept the original shifter. How did that work because doesn't the 4R have the P-R-N-OD-D-2-1 pattern while the cougar original shifter has a P-R-N-D-2-1 pattern? Just curious how you made it work. Thanks
 
#5 ·
Flywheel and block plate will be the same. You might get by using your drive shaft BUT you would have to either change your yoke (to a larger 4R70W style), or replace the extension housing on the 4R70W to accommodate the smaller early AOD yoke.
Send me a PM with your email. I have an article that might interest you. It was written by a gentleman who replaced his early AOD with a 4R70W. He goes into detail about what does and does not swap.

The pattern on my 4R70W is P-R-N-D-2-1...same as my original. The gentleman who produces the 4R cross members will be producing the 4R shifter rod soon. I am trying to get a hold of one.

4R has an button for the overdrive select/deselect on the shifter.

BTW, you can also use a 4R70W from a 5.0 Explorer/Moutaineer. Lots of those in junkyards, thanks to $4C...
I could only find the 4WD version with the funky extension housing. I imagine a 2WD version is preferred...but good point, I forgot to mention that.

Cougrrcj, out of curiosity can you confirm if the 4R will bolt to a 351C?
 
#4 ·
4R has an button for the overdrive select/deselect on the shifter.

BTW, you can also use a 4R70W from a 5.0 Explorer/Moutaineer. Lots of those in junkyards, thanks to $4C...
 
#10 ·
Yes, about 80% happy.

I am fighting with the electronics a little bit. The TCS controller allows you to do just about anything…problem is the instructions do not clearly explain the many different functions. The adjustable converter clutch is especially perplexing. It will take some time to get everything dialed in correctly…

I do like 4th gear, the wide ratio gear set, and the fact that it doesn’t leak from 83 different places as my C4 did.

Keep in mind I have driven it maybe 5 times. I will post back after I drive it more. It's just too darn hot to be driving around with my AC currently not working (that should be fixed tomorrow).
 
#7 ·
SBF bellhousing pattern is SBF bellhousing pattern - now flexplates might be an issue since the Explorer's is 50oz, but I would imagine that any 5.0/5.8 28oz AOD flexplate would work for a 351C providing the converter bolt pattern is correct.
 
#8 ·
BTW, if you source a Crown Vic 4R, remember that police cars (P71 in VIN) and Town Cars used a 1" longer tailshaft housing
 
#12 ·
Email sent.

Just to address question about 4.6L 4R70W...you will want a 5.0/3.8/4.2 only
Baumann said:
The bell housing pattern is different for a 4.6L or 5.0L/3.8L/4.2L engine and the two are incompatible. The two case types can be distinguished by looking at the starter flange area. If the starter has three attaching bolts, the case fits only 4.6L engines. A two-bolt starter indicates a 5.0L/3.8L/4.2L compatible case (casting number may begin with "F4ZP", not available before 1994).
http://www.becontrols.com/tech/ch4usedtrans.htm
 
#17 ·
Well it seems to have more get up and go which I credit to the wide ratio gears.

I have not calculated the mileage yet. Again, I have not driven it much since the AC was out.

I was doing about 11mpg before...
 
#18 · (Edited)
Update: The 4R70W is working well. I am finally happy with the tune. :)

To update my original post, I do not recommend removing the lower accumulator springs according to the J-MOD. The 1-2 shift was especially violent and would chirp the tires at any throttle position. It was far too aggressive for my liking. I ended up pulling the pan and reinstalling the 1-2 accumulator spring which helped greatly.

Current Calibration:


The next step is to calculate my MPG...and fix my belt light which as you can see does not shut off (bad relay)...
 
#20 · (Edited)
Just a FYI in case it wasn't mentioned earlier - The gear ratios of most ford three-speed automatics are 2.40. 1.45 and 1.00. AODs have the same ratios, but with the addition of the .67 overdrive. The 4R70W has ratios of 2.84, 1.55, 1.00 and a .70 o/d.

The 4R70W was developed so cars could use an even lower rear gearset for economy, yet still have the get-up-and-go with the low-torque motors like the 4.6L in a heavy car like the Crown Vic, Explorer and Expedition or the V-6s that are used in smaller cars and trucks. The wide-ratio gearing of the 4R70W makes a performance car out of just about anything.

First gear in 4R70W is 2.84:1 instead of the normal Ford auto trans 2.40:1. Looking at the two numbers, you'd think that is not all that big a deal, but the difference is 18%. In other words, it makes a 3.55 rear end feel like 4.19s off the line, yet you have the 1:1 Third gear, and you still have a respectable overdrive ratio that makes those same 3.55s act like 2.48 'highway' gears on the open road. With today's more common stock gearing of 2.73s, the effective First gear is 3.22 off the line, and a extremely low 1.91 o/d effective gear on the open road - great for CAFE fuel mileage!!!
 
#23 ·
Yup, the wide ratio gearing coupled with my 3.55s really gives the car some get up and go. I am very happy with the outcome.

As I mentioned before, I was quoted an additional $300 to upgrade a early non-electronic AOD to a wide ratio gear set….and here I paid $200 for the entire 4R70W transmission with torque converter.

James, I will be at Bill's place on Saturday. My family is having a retirement dinner for my dad that evening so I will likely have to leave by 5:00... Hope to see you there.
 
#21 ·
Just ran across this thread for the first time. Excellent work Joe! Love modern technology applied to our vintage cars! :beer:

Regards,

Bob
 
#22 ·
Joe, glad to see you back enjoying your cat. Are you going to be at Bill's Saturday?

I still have to get my settings dialed in but my experiance matches Joes. Last summer to and from the prowl I averaged 21 miles to the gallon with 3.55 rears. Compare that to Mistress running a 289 with 3.0 gears getting 14. Altough the previous prowl when I had 3.0 and the FMX I still got better mileage by 2 or 3.
 
#25 ·
That is true, but I was in the $1,800 range when I priced out a "built" early AOD (wide ratio) with converter.

$1,800 > $850 ($200+$650)

I know I am comparing apples and oranges here as one is rebuilt and one is used...plus they do not have the exact same internals, but still.

Now, my story might be different if I had access to cheap cores, and could rebuild a transmission myself.:)
 
#28 ·
...Now, my story might be different if I had access to cheap cores, and could rebuild a transmission myself.:)
Joe,

Just a few words hopefully of inspiration. Way back when I was 17-18 and my first car, a 68 Toyota Corona lost reverse, I became a trans rebuilder - by necessity. I never looked back and I have built numerous transmissions - manual and automatic since. These were built by men and can be fixed by men, that is my philosophy. You can do anything really, given the will and the skill. No, not everyone has the latter, but given the right attitude, you can do amazing things. This works for me, it's one of the mnay spices of life that I really enjoy. Learn something every day, how fun is that? A lot.

Regards,

Bob
 
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#26 ·
The trickiest part of the WR-AOD is getting the overall endplay within tolerance. Had to buy the select-fit thrust washer 'kit', and made sure to use all of the the other 4R70W thrust washers since they're different than AODs... Of course, both transmissions use lip-type seals on the servo pistons and clutch pack pressure plates, so you need the proper installation tools. The installation tools ran about $35, the A++ servo was $110, hardened input shaft was $135, rebuild kit was $85, bands were another $45, bushing kit another$... You get the picture.

When the weather breaks, I'll be yanking either the engine or trans so I can send my torque converter back to the manufacturer for a 're-stall' to 3200 - $85+shipping. I gotta get this 4000-pound street-driven brick into the 12s! LOL!!

 
#27 ·
The converter for me almost cost more than the transmission. I did a combination of both you. I had the transmission rebuilt with all the good stuff a 2800 converter and a TCI Controller. The baumann wasn't available at the time. Priced out though it was almost a wash between a built AOD and the 4R70W. I think the difference was less than a $100.00. Another good thing is when I finally get off my @ss and get some new gauges I can switch to electronic w/o and adapter and the computer will interface seemlessly for EFI.

Just have to go play on the computer a little to make it perfect. I'll see you tomorrow Joe
 
#29 ·
^^^What he said^^^

Back in the stone age (1978), the trans went bad in my '73 Buick Electra. I ended up paying a shop $600 to rebuild the trans in a car that only cost me $1100... From then on, I started doing them myself. Most of the time it was just a matter of replacing seals, along with the clutch pack friction and steel plates. The worst part of the job was getting the trans out of the car past the rusty exhaust, and working with the car on jackstands in the driveway, etc...

Then I found a local place that did budget replacements for $125 carry-out or $200 installed, with a 2-yr warranty! I couldn't rebuild a TH350 for that if I found the intermediate sprag was toast (the cause of most TH350 demise)! They got a lot of my work, just because of the installation hassles. They had the lifts and I was still laying on my back in the driveway... The problem was that they wouldn't touch a car with aftermarket trans mods. So, back to the driveway I went...

Now I'll just go over to the junkyard and get a core trans ($25 at most) if I don't have one already, and take my time rebuilding that one so my car isn't on jackstands in the driveway or garage for a week or longer while I chase down pieces-parts.
 
#30 ·
Yeah, I am all for doing as much work possible myself. In fact, the car has never been to a mechanic of any kind. I even do my own alignments. I typically tell people that I did everything but paint the car, and the paint is the only part I am not happy with.

I will certainly consider rebuilding my own transmission if the need arrives.

Thanks,
 
#32 ·
not to go good or bad , but my opinion, if your going to go with a full on 4r70w with elctronic controls , why not just efi the car and be done with it? using a setup from a 94-95 gt mustang will net you all the needed hardware! + you get acess to all that cool laptop tuning abiltys to make it run the way you want it to
justin
 
#33 ·
With my 27" tall tires, I'm using a 21-tooth 'purple' speedo gear. BUT, you have to remember that AOD output shafts had either a 7- or 8-tooth gear built into them. I *think* 4R70Ws all have seven tooth drive gears... So.... the driven gear you need is dependent on the teeth on your output shaft.

Check out these links -

you'll have to scroll down for the Ford section (sorry) ;)
http://www.transmissioncenter.net/speedometer_calibration_______va.htm

and then there is this one that will calculate the gear you need based on drive gear, rear end ratio and tire diameter:
http://www.sccoa.com/faq/speedgr.html
 
#34 · (Edited)
Edit:
Thanks! Looks like it has a 8 tooth output shaft.
8-Output, 26.40 Tires, 3.55 = 21.7

I currently have a orange (20).

jk69cat, I would like to…but I keep telling myself to drive and enjoy the car as is. I have to stop taking the damn thing apart.

The car has been on the road for 2-years and I have driven it 800miles…Must drive, not take apart. :)
 
#36 ·
There is someplace that makes 'Black' 22-tooth speedo gears. BUT the teeth are so thin that they wear out quickly (~15k miles).
 
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