Automatic Overdrive Transmission for Big Block

[[email protected]]

Hi Everyone! -  

The quick question:  What type of automatic overdrive transmission can I install in a 71 mustang with a 429 engine?

::thumb::  The details:  It's a 71 convertible.  I'm replacing the original 6 cylinder / C4 tranny / 8" 28 spline rear with ------> 429 SCJ (dyno shows 572 HP at 5000 rpm and 617 Ft-lbs at 4600 rpm) / 9" 31 spline rear with N-case, Trac-Lok, with any choice of gear ratio, and the choice of transmission still up in the air.   

:chin: The quandary:  No luck by looking at previous threads.  I have all the "stuff" to make the switch, but haven't decided yet on a transmission.  I have several spare C6 trannies that came with the Cobra Jet engines (R servo and iron tail housing) and can rebuild and install one of these.  But I would rather go with an Automatic Overdrive because, like everyone else in the world, I like both good acceleration and high speeds, and I'm not keen on a manual OD tranny because I like to drink my coffee while I'm driving.  Articles on this subject usually involve trucks and not passenger cars.  Some authors suggest the original Ford AOD or the Ford E4OD, with the latter more often recommended because it's a beefier transmission.  Other articles say the E4OD is too big to fit in a passenger car.   I would rather not go with an overdrive kit for a C6 for various reasons. 

:huh:  The In-depth question:     What's a Ford Lover to do?    :thankyouyellow:

 

[Don C]

Go with a C6 and Gear Vendors overdrive, so you can handle that power.

https://www.gearvendors.com/index.html

 

[Jeff73Mach1]

C-6 and Gear Vendors is the best of both worlds

Stick a 4.30 differential and go from mild to wild with the push of a button

 

[[email protected]]

Thanks for the great lead! Never heard of this option before. I read the web site up and down and all around. The Gear Vendors device is a really interesting concept and looks to be easy to install. Many advantages to this conversion!! But there's a distinct disadvantage that would still make me want to consider a E4OD or an AOD dedicated transmission: This system simply adds on to my old transmission. I still need to rebuild the old one, install all the high performance items, new torque converter, etc. So the final cost will be about $2.5K for the rebuild plus $3K for the Gear Vendors device. So the Gear Vendors route will cost $5.5K to get an automatic overdrive transmission. I can obtain and build a nice E4OD or AOD for just the $2.5 K. I may still consider the Gear Vendors device, but back to the original question - Will an AOD or E4OD with a 429 bell housing bolt pattern fit in a 71 Mustang?

 

[TommyK]

E4OD is a very large trans and may require trans tunnel mods. 4R70W with adapter and an electronic controller is the way to go IMO.

 

[Mister 4x4]

E4OD is a very large trans and may require trans tunnel mods. 4R70W with adapter and an electronic controller is the way to go IMO.

:goodpost:

Both are solid solutions!  ::thumb::

 

[Don C]

An AOD's weak link is the input shaft, due to the mechanical clutch lockup design, which requires the shaft to be hollow so that a lockup shaft can run through it. An AOD that would be strong enough for that motor would require a solid input shaft and eliminating the clutch lockup torque convertor.

You can get an E4OD with a 429 (460) bellhousing. An AOD or AODE/4R70W will require an adapter between the transmission and engine.

The E4OD and AODE/4R70W transmissions will also require an electronic transmission controller.

Not all E4OD transmissions have the speedometer drive gear machined into the output shaft and would require either running an electronic speedometer or an electronic to analog speedometer converter. Not only will an E4OD require transmission tunnel modifications they hang much lower than a C6 or the smaller OD transmissions. You would likely have to use shorty headers from FPA and a custom exhaust to clear it.

All of the transmissions mentioned can be built to handle your engine.

 

[[email protected]]

Great. Thank you everyone for these suggestions. I'm definitely going to look into these two new options (Gear Vendors, 4R70W). I very much like the gear ratios of the 4R70W which are First: 2.84 :1 Second: 1.55 :1 Third: 1.00 :1 Overdrive: 0.70 :1 I don't think it was ever matched up to a 460 engine, hence the need for an adapter.

 

[Don C]

You are correct, the 4R70W was never installed on big blocks. E4ODs evolved from the C6, while the AOD, AODE, and 4R70W evolved from the C4.

Yes, the low first gear for the 4R70W is great. You can also get a wide ratio gear set for the C6, which has a 2.72:1 first gear, not quite as low as the 4R70W, but better than stock,

http://www.ckperformance.com/List/C6/Ford-C6-Competition-Components

 

[Fabrice]

while the AOD, AODE, and 4R70W evolved from the C4.

Oh, thought I've red multiple times that the AOD was actually the grand child of the FMX.

Having both, they do feel/act pretty much the same.

I want also one day to have overdrive on the 429. VG look like the best option, no issues/probs to solve as with a trans swap, they are direct install on the C6.

but man, these things are expensive... pfff

Btw, hijacking a bit the thread with a new question. Why are overdrives ratio's most of the time .7 ?

 

[Ed Raver]

On a personal note, I broke my E4OD   twice    in one year when I first got it in my work truck. It was not abused and Ford was great about replacing it but no more of those for me.   Ed

 

[[email protected]]

Hey Don C, thanks for the great reply. the CK Performance stuff looks great.

 

[Jeff73Mach1]

I see the GV units for C-6's sold on craigslist or marketplace etc fairly regularly. Generally a complete used unit is pretty reasonable (1/3 the price of new) and they are pretty sturdy units.

 

[Don C]

You're welcome. There are a variety of options available, and what's available may help to make the decision on which way to go.

 

[red351]

I use GV so I can keep the toploader and 3.50 rear gears for interstate, other than that, c4/fmx/c6 no

 

[Hemikiller]

Spendy, but if you gotta have an overdrive...

http://www.performanceautomatic.com/news/259/BBF_4R70W_SUPER_COMP.html

 

[Don C]

PA has some nice transmission options, but like you said, spendy.

May as well as go with the 6-speed (my dream transmission)

http://www.performanceautomatic.com/products/ford-racing-transmissions/6r80-transmissions/6r80-street-smart-systems.html

 

[JJU9507]

Old post but you could fit in a 6R 80 really the best transmission out there no drums they will fit. You remove the transmission mount reinforcement from the floor pan and mount a new one from Stiffler‘s outback. adapter plate you can get from Performance automatic Or Bensons adapters. these transmissions are new enough. You can get a used one that’ll work fine, I’m leaning towards this although I would like to put a five speed TKX but that’s a lot more effort to convert to a stick shift since mines an automatic big block 521.