AOD swap? And why not

[Gatordog]

I am doing a frame off restoration on my 73, and was going to have the C4 rebuilt. Then I noticed lots of people are running the ford AOD instead. The cost for having the C4 rebuilt and buying a strong AOD from JEGS is nominal. My question is other than a custom transmission mount from Broncohut, what else is needed? Like transfer case adapter, shifter for transmission and shifter for T-case, custom length axles? I would really like a overdrive transmission, since this Bronco is going to be a daily driver

 

[bronconut73]

4R70W not the AOD.

It is stronger, better gear spread.
It will be cheaper in the long run.

You can run a Ford NP205 then you won't need the adapter but you will need cross member mods and drive shaft mods.

 

[Broncobowsher]

You don't want the AOD, the 4R70W is where it is at.
Local transmission shop will do it for much less than mail order. Also they can install the tailshaft and tail housing bolt the bronco D20 right up.
What gears are you running now? What size tire? Are you planning on regearing as part of this transmission swap? Because you will probably need to and have not thought of that part of the budget. Most Broncos are not set up gearing wise to accept an overdrive. Just too tall of a gear.

 

[doran4x]

You can use the 4R70W gears in the AOD case if you don’t want to run a computer to control shifting. The late model 4R70W, 1998 and later, is the better transmission. Ford improved on the design and strengthened the internals.


Sent from my iPhone using Tapatalk

 

[Steve83]

To use an AOD, I had to stack a few washers & grind a couple of holes into the original crossmember, which was bolted in a few inches back, requiring d'shaft changes.


https://www.supermotors.net/registry/media/70487


https://www.supermotors.net/registry/media/71779


https://www.supermotors.net/registry/media/608095

It worked perfectly for more than a decade, and probably still is for the new owner.

 

[englewoodcowboy]

I like both the AOD and 4R70W. I can tell you after doing a few the pros and cons of different gear ratios are so negligible for a DD use there really is no real noticeable difference. I run an AOD in my bronco and it is built to handle 500HP and I was cheaper than going 4R because I did not have to buy a computer. I also did not upgrade the gears, it simply was not needed and the old school of thought, yes the AOD was notorious for burning up the OD clutch however with a proper build, increasing line pressure and clamping force, they hold up just fine under high performance. Now the biggest difference is $600 give or take is not going to sway you is the 4R can be programmed for your shift points etc. The AOD is mechanical and they all have to be worked out at the time you are selecting components and building it and there is little to no adjusting it afterwords. That is what you really need to ask yourself, do you want to really dial it in or can you save some $$ and live with a decent transmission. For my customers I push them to the 4R simply because most only understand the cars they drive today and want their bronco to behave as close as possible. For the who are mechanical and understand the older tech and want simplicity, then the AOD is a great foundation.

 

[Gatordog]

I will be running 31 in tires, don’t know my gears. I really don’t want a computer, and the JEGS AOD is rated for 450hp. If the C4 want be making the motor scream at highway speeds (75) then it sounds like I don’t need a overdrive.

 

[bronconut73]

Figure out your axle gears Bud,

That's the first step for ya.

 

[englewoodcowboy]

Figure out your axle gears Bud,

That's the first step for ya.

Agreed. For 31's you need to look at 4.11 with an AOD because it has a healthy OD. That would put you turning 2089 RPM's at 70mph. Would be a damn good runner at that. If you stayed with a C-4 and stock 3.50 gears, you will be turning 2806 RPM's at 70. It won't hurt the motor but it will be wound up going down the road.

 

[Broncos n' VWs]

I've ran 33 inch tires with 4.56 gears and it was decent. I went to a 35 inch tire and with the 4.56, overdrive is borderline tolerable. You need to figure out your gear ratio in your axles. If you are running stock gearing (3.50) then you need to remedy that before thinking about the overdrive transmission. 31 inch tires and a 4.56 would be just about right with the OD.

 

[KeithKinPhx]

Went with the 4R70W and doing the install as part of the restoration. Liked the fact that gears 1-3 match the old 3 speed manual and you get the bonus 4th gear as OD. Running the 289 with FiTech 400. Not super mechanically inclined so tuning the AOD is not something I will mess with. Plus if you don't like a shift point (up or down) you can change on computer. Although it cost more I like the flexibility of the 4R70W.

Repainted engine bay, adding AC, Lizardskin and new seats. May be while before it sees the road. Videos on YouTube under Rising Phoenix Bronco

 

[Bart]

I have an AOD built with the AODE first and second gear ratios. That is 2.84 vs 2.46 and 1.54 vs 1.20 (something). I also purchased a valve body from Len Tech in Canada. That valve body gives me shift control of 1st, 2nd & 3rd on the shifter with electric overdrive on the dash. I run 5.13 gears with detroit locker in the rear and selectable OX locker up front. My transfer case(S) are a New Process 203 stacked in front of a 205. That gives me low, medium and high range. For more than 7+ years I've wheeled it HARD through Moab, Utah, Rubicon, Fordcyce Creek, Dusy Ershirm and all around Arizona, and Big Bear in commifornia without an ouch of trouble. I know a guy who works building transmissions at a Ford dealer and he builds them on the side too. I love my setup. With the overdrive I can still drive my 5.13s on the highway. If you're interested I can put you in touch with friend.

 

[Gatordog]

Sounds good, I will be using this Bronco more for the street so I wanted a transmission that can cruise all day at highway speeds without a screaming motor. I also want to avoid computers, it sounds like a hybrid transmission is the best. An AOD case with upgrades sounds go to me.

No rush, I am still disassembling and degreasing. Next week I will get a Explorer motor and then take the body to a body shop that will repair the rusty bits

 

[Bart]

On a side note, I have another stock AOD done and waiting to be installed in my '75 EB Ranger. When I get some free time that is. With 4.11 gears it should be a great all around rig with nice off road manners. I'm going to order another Len Tech valve body also. If you decide to go with the Len Tech valve body don't let them talk you into a NON lockup torque converter. It'll boil the ATF on the highway. Voice of experience speaking here.
It also looks like we have something else in common. I see by your signature you have a 2000 7.3 PSD dually. I also have a 2002 7.3 PSD dually. That's my tow monster. I pull a 40' 5th wheel toy hauler. Wanna bet what's inside? Bronco of course. Loaded to the gills but the big Ford doesn't care.
One place we differ on is your "never ride" motorcycle. You can't keep me off my 2011 Harley Electra Glide.

 

[American180]

Here's a nice chart showing the RPM change per tire size and gear ratio. You could do the math to figure the change with overdrive.

 

[Gatordog]

Yes sir, you just can’t get better than a old 7.3, they just run. I added a 6.0 trans cooler and that really helps.

I would like the transmission setup you have, but there is no transmission shop within 100 miles I would trust. I could go with the newer one if needed.

I still need to go to the you pull it and get the Explorer 5.0, they have 3 with no frontend damage. I will be pulling the engine with front brackets. What other parts should I pull from the Explorer?

 

[Hazegray]

I've been running an AOD for over 10 years, nada a problem. With a 351W, 33 inch tires, 4.11 gearing, it does not lack power on the highway or around town. That being said, my AOD shifts rather quickly through the gears, 1-2-3 up to 40mph, then into OD around 45 mph.

 

[Bart]

Here's a nice chart showing the RPM change per tire size and gear ratio. You could do the math to figure the change with overdrive.

Nice chart overdrive is in the .66 or .67 range so an final drive rpm should be multiplied by that figure. Also with a lock up torque converter there is no slippage as noted on the chart. In my case, my 5.13s equate to 3.38. That's an rpm change from 3200 rpms down to the 2,000-2,000 rpm range. Yes, that's where my tach is at 65 mph.

Yes sir, you just can’t get better than a old 7.3, they just run. I added a 6.0 trans cooler and that really helps. I keep mine in the garage and only comes out to work. It's not a daily driver/grocery getter. The EPA bastards killed the 7.3. When I talk with other diesel owners that tow I ask them "if they were going to tow something large would they want to use a 351 Windsor (6.0 litre) or a 460 (7.4 litre). I rest my case.

I would like the transmission setup you have, but there is no transmission shop within 100 miles I would trust. I could go with the newer one if needed.

Where do you live? Transmission can be shipped. My friend (Bud) builds a killer unit. Years ago he built my trans, then not so many years ago I changed from the Dana 20 to the 203/205 combo. This required Bud to gut the transmission to change the output from the 20 to a different 203 setup. He stated that "knowing what I do with my Bronco, I expected to replace a lot of parts. He told me after returning it that it looked like he had just built it" ​

I still need to go to the you pull it and get the Explorer 5.0, they have 3 with no frontend damage. I will be pulling the engine with front brackets. What other parts should I pull from the Explorer?

Is the Explore the donor for the trans? If so, I'd also try to get the cooler lines and torque converter for sure. Does your Bronco have a column or floor shift? Are you going to stay with the same shifter or change to the other style. I imagine the donor has a column shift the won't do much good. Do a little research to see if the starter motors and flex plate (aka drive plate or fly wheel) are the same. EB are 164 teeth the starter and the flex plate need to match. Also, very important is the AOD control for pressure. You might be able to use the rod from the throttle body to the trans (not the shifter but in the same place) IF you are running a similar fuel injection system. If you're carburator or after market EFI then you'll need a cable from Locar. Not sure of the spelling of their company though. They make cables for everything.

I've been running an AOD for over 10 years, nada a problem. With a 351W, 33 inch tires, 4.11 gearing, it does not lack power on the highway or around town. That being said, my AOD shifts rather quickly through the gears, 1-2-3 up to 40mph, then into OD around 45 mph.

From what friend "Bud" tells me the shift in o.d is about right. That's controlled by the throttle pressure cable I mentioned above.

 

[englewoodcowboy]

I've been running an AOD for over 10 years, nada a problem. With a 351W, 33 inch tires, 4.11 gearing, it does not lack power on the highway or around town. That being said, my AOD shifts rather quickly through the gears, 1-2-3 up to 40mph, then into OD around 45 mph.

You can safely increase TV pressure to swing all of the shift points up. I have mine set at light throttle, approx 1/4 input where it shifts 1-2 at 12mph, 2-3 at 32 and it holds 2 in that range up to 30 mph letting off it does not shift to 3rd which is very nice for light trails gravel roads etc. and 3-4 at 50mph. My only complaint is when I built the transmission I installed the second stage shift correction kit as it said for towing and truck use. My 1-2 shift is very firm, all other gears are very nice shifts so when it is time to do a service and I have the pan off, I will be doing some re-calibrating to lighten the 1-2 shift. Knowing what I know now, the stock shift correction would have been more than sufficient.

 

[Gatordog]

Is the Explore the donor for the trans? If so, I'd also try to get the cooler lines and torque converter for sure. Does your Bronco have a column or floor shift? Are you going to stay with the same shifter or change to the other style. I imagine the donor has a column shift the won't do much good. Do a little research to see if the starter motors and flex plate (aka drive plate or fly wheel) are the same. EB are 164 teeth the starter and the flex plate need to match. Also, very important is the AOD control for pressure. You might be able to use the rod from the throttle body to the trans (not the shifter but in the same place) IF you are running a similar fuel injection system. If you're carburator or after market EFI then you'll need a cable from Locar. Not sure of the spelling of their company though. They make cables for everything.


From what friend "Bud" tells me the shift in o.d is about right. That's controlled by the throttle pressure cable I mentioned above.

The Explorer is a donor for the engine. I will need to buy a AOD transmission and what ever adapters are needed if any, I would like to keep the factory column shifter if possible. I plan on running a carburetor, so no computer

Send me your friends information or a quote on AOD with adapter for the stock transfer case.