Transmission

[oly24]

I would like to know what would be the best,easiest and cheapest automatic overdrive transmission and transfer case to install in a 75 EB? Plus what would be the best doner vehicle. Thanks for any help. I am installing a 1988 mustang EFI Right now if this matters or helps

 

[broncnaz]

Probably a AOD with the stock EB t-case. Most of the other swaps require control boxes to allow them to run so the price increases but they can be better choices in the end. Check out the tranny swaps section it should give you a idea of whats involved.

 

[Broncobowsher]

Best, easiest and cheapest are usually 3 different things.

Best (fairly easy and not cheap) would be a 4R70W with an aftermarket transfer case such as a Stak or Atlas.

Easiest is to use a 2WD transmission and leave off a transfer case. 2WD hack job. But it would be nearly pointless.

I will simplify it to 2 transmissions. AOD and 4R70W. The quick and cheap way to mount either is to use an NP205 transfer case behind a factory 4WD transmission. AOD is cheaper way and the 4R70W is a better transmission. Both can be done without opening the transmission. Keep in mind you are liiking at a 15 to 20 year old AOD which had poor engineering in the early ones. The 4R70W is in the 5 to 10 year old range.

Any way you cut it requires driveshaft modification.

My recomendation for a low buck, quality transmission swap. 4R70W from AWD Explorer V8 ('96 to '01 5.0 V8 only), Late 70's NP205 (can't hurt them as long as there is oil in them).

All overdrive swaps will require a miniumu of extensive modification of the transmission crossmember or fabrication of a new one.

Be warned this will quickly become a repeat debate thread over transmissions. There are also other factors like how good of a tranmsission do you want? You can pick up a $50 junkyard bomb from an '85 F150, drop it in and hope it lasts a month behind a 5.0 mustang engine all the while it short shifts as the governer springs are for a truck engine and the torque compensation is for a 2 barrel carbed gutless wonder.

There are countless threads on this. Many writeups in the tech section as well.

And while we are at it, what size tire and what axle gears are you planning on running? An overdrive may be pointless for you anyway unless you regear your axles. Most of the mid to late 70's seam to have 3.50 gears in them. That gear and an overdrive don't work together too well unless you are looking at running stock tires sizes. Even with 4.10 gears an overdrive isn't going to be any good over about a 31" tire.

Expecting massive fuel economy gains? don't.

 

[oly24]

Thanks for the info not sure what to do I have an aod from a 88 mustang I bought the whole car for $450 and thought I might be able to use the transmission with the engine. Oh the bronco has 4:10 gears and the tires will either 31 or 32

 

[fordguy]

you will have to have an adapter for the stock D20. AA makes them. Are you going to run the efi? If I found the aod cheap enough I would not mind running it. The adapter kit is around 500 dollars I think.

 

[fordguy]

with the aod and 31.5s you would be at about 1900 rpms at 65mph

 

[oly24]

yes. I bought the mustang for $450 dollars good strong engine I know the guy I bought it from he sold it two months ago to one of his friends and the guy smashed into a telephone pole still runs good and shifts fine so I figured for $450 I couldn't lose. I will take all of the EFI parts and wiring and what ever else I want and then part it out to get back some of my money.

 

[fordguy]

here is the adapter http://72.20.96.178/commerce/ccpc10...aod-to-bronco-dana-20-ada-50-2704-50-2704.htm
It can be found cheaper. If i found a donor that cheap I would get the adapter and run the aod until it needed a rebuild. Good luck. Did you see the RK wiring harnesses, he does speed density and Mass Air. Is your SD or MA?

 

[oly24]

It is speed density. The transmission was rebuild two years ago so that it could handle the poor from the engine I was told some thing about the clutches being upgraded or something like that. Was not listening to every detail!

 

[needabronco]

Run your AOD, and keep an eye out for a junk 4R70W and grab it for the low gear set. When you AOD dies swap out the gears for a cheap upgrade. Tom's has the adapter kit for less than $500, and a 'bolt up' crossmember for around $180 to make life easy... Note if you have the whole car you already have 80+% of your swap.

 

[oly24]

what vehicle did the 4R70W come with

 

[needabronco]

V8 Explorers, 1997 and newer mustangs ( you want the V-6 trans(2-bolt starter), not the 4.6(3-bolt starter). There are many many others, in fact, I think there still being used in new Fords. Incedentally I remember seeing a 4R70W planetary gear set on ebay for around $50 a couple of days ago.... Good luck.

 

[PaulS]

You can swap the gears into the AOD if you do it properly.

 

[Hazegray]

I have the AOD in mine and was told (by the transmission shop that rebuilt mine) that you have to get into the transmission to swap in the output shaft from the AA adapter for the D20. True or not? Don't know, but you may want to ask AA that question to verify.

 

[needabronco]

Yes, you have to completely disassemble an AOD to install the adapter. From what I can tell it can be as simple as a disassemble/reassemble job. If you have the book, and right tools, and pay attention I don't think it would be too bad. If it needs a rebuild or has problems I would add a kit at that time and/or take it to a shop for the rebuild. You can always try it and if you get lost, then take it to a shop. I plan to atleast attempt to do mine myself.

 

[Incognito]

check out this site for options

http://www.high-impact.net/transmission_and_gear/vehapp_early_bronco.htm#AutoTransConversionOptions

 

[Broncobowsher]

I have the AOD in mine and was told (by the transmission shop that rebuilt mine) that you have to get into the transmission to swap in the output shaft from the AA adapter for the D20. True or not? Don't know, but you may want to ask AA that question to verify.

A little more then just get into it. You need to completely gut it. The whole transmission is built off the output shaft. Every moving part inside the transmission has to come out to access that shaft.

 

[PaulS]

Yep! the output shaft is the last thing that comes out of the case.
This is not something the average back yard mecanic has the tools or skill to do. Consult a professional.

 

[oly24]

what if I use a transmission and transfer out of a 89-90 full size bronco would this fit ?

 

[Broncobowsher]

what if I use a transmission and transfer out of a 89-90 full size bronco would this fit ?

This question comes up about every 2 weeks. I guess it is time again.

No. It will NOT fit. The frame on an early Bronco is too narrow. If you find a NP205 to replace the late model transfer case then that has been made to work.