Swapping a C4 for an AOD Issues ?

[JAFHR]

I've looked through the archives and haven't found too much info. I'm sure it's there somewhere, but I'm gonna ask anyways.

I blew my C4 and was talking to someone about why I don't put in a non electronic AOD. The way I understand it, it would need to shorted the the rear drive shaft and lengthen the front. Other then that would this fit without an adaptor or ? What am I looking at in order to install it. Is it worth it. I'd certainly like to have overdrive.

Thoughts ?

 

[bronconut73]

4R70W with a US shift or Baumann controller is where its at Bud.
The Ford AOD just isn't near as strong as the 4R70W.

No adapter at the engine but you need one for the Dana20. If you were to run an NP205 TC it would bolt right up to that tranny, no adapter needed. BC has a partial Cross member kit for the 205. Just another option. The 205 is wide. Dual exhaust is tougher....not impossible but tougher.

 

[blubuckaroo]

Personally, if I were faced with replacing both the tranny and transfer case, I would probably use the GM 700R4 tyranny and the GM transfer case.
Reason?
First is the 700R4 has a better low gear.
Second, it cheaper.
Third, it'seems just a better tyranny.
And it fits too.
Fourth, it fits an LS motor without any adapter at all.

 

[crutch]

From someone who went the AOD route thinking I would save some money over the 4R70W and would be easier, it has ended up costing me way more money then I thought. Bought a used one that was supposedly rebuilt, I took it to a transmission shop before I installed and ended up needing a rebuild which is fine but the TV cable pressure setting is a PITA depending on the carb and linkage you are using. I would highly recommend evaluating the 4R70W. I wish I would have taken others advise to get a stronger transmission, better first gear ratio and greater control of shift points,

 

[garberz]

I'd stick with the C4, overdrive is nice, but you'd really have to want it. I cruise mine all day long at 3000 rpm. Gives me 60-65 mph. The AOD has the same 1-3 gear ratios as the C4, it's not as strong, you need an adapter for the t-case, fab a rear crossmember, drive shaft mods, and linkage mods. Lots of cost involved for just an overdrive gear. Stick with the C4, or go with a worthwhile upgrade (4R70w) if you're looking to spend that kind of money. The C4 is cheap to rebuild.

Mark

 

[Broncobowsher]

As mentioned above, 4R70W is a way better option for an overdrive automatic over the AOD.

Will you need an adaptor? Yes. As long as you get the right case to start with (2-bolt starter, small block bolt pattern) it will bolt to your engine just fine. But the transfer case is more difficult. Couple options to keep the Bronco T-case but they all take adaptors. And the modern chain drive transfer case you may find, that won't work as it is too wide to fit in the frame rails.

Just because you put an overdrive transmission in, can you even use it? While you may think you are turning a lot of RPM on the highway most people don't have enough gearing to use the overdrive. The Bronco is not a Mustang or even a late model pickup. There is a LOT of drag, rolling and wind. It takes HP to shoot the brick down the road and punch through that drag. To get that HP you need a bit of RPM. A pretty good generic target is 2000 RPM at 60 MPH. You need to go through the RPM/gear/speed calculator to see what works for you. In short, expect to need axle gears as well as the new transmission for that overdrive to work. The good part is those low gears make driving around town and running anything off-road so much more fun. Don't fear the gear. Anyone who says the high gears are fine has not enjoyed the pleasure of what a low set of gears can do and is probably living in denial.


Best option, just get the C4 rebuilt. Unless you have plans to build it correctly to accept the overdrive it isn't a good choice.

 

[Faster Eddie]

As mentioned above, 4R70W is a way better option for an overdrive automatic over the AOD.

Will you need an adaptor? Yes. As long as you get the right case to start with (2-bolt starter, small block bolt pattern) it will bolt to your engine just fine. But the transfer case is more difficult. Couple options to keep the Bronco T-case but they all take adaptors. And the modern chain drive transfer case you may find, that won't work as it is too wide to fit in the frame rails.

Just because you put an overdrive transmission in, can you even use it? While you may think you are turning a lot of RPM on the highway most people don't have enough gearing to use the overdrive. The Bronco is not a Mustang or even a late model pickup. There is a LOT of drag, rolling and wind. It takes HP to shoot the brick down the road and punch through that drag. To get that HP you need a bit of RPM. A pretty good generic target is 2000 RPM at 60 MPH. You need to go through the RPM/gear/speed calculator to see what works for you. In short, expect to need axle gears as well as the new transmission for that overdrive to work. The good part is those low gears make driving around town and running anything off-road so much more fun. Don't fear the gear. Anyone who says the high gears are fine has not enjoyed the pleasure of what a low set of gears can do and is probably living in denial.


Best option, just get the C4 rebuilt. Unless you have plans to build it correctly to accept the overdrive it isn't a good choice.

This is on point!


Sent from my iPhone using Tapatalk

 

[Broncos n' VWs]

I couldn't have said it any better than BroncoBowsher. Most of his opinion and tried and true expertise helped sway me on my 4R70W conversion over 9 years ago. I did the swap and I haven't regretted it one bit. I say you either rebuild the C4 and bullet proof it or look into the 4R70W conversion.

 

[rguest3]

JAFHR - What percentage of your driving is at highway speed? (65+)

I have 2 Broncos that will rarely see over 60MPH. Both have C4s. No reason to change them to AOD of choice. With correct Tire/Gear combo maybe you won't need to change either???

 

[sanndmann3]

I would go 4R over the aod. I got rid of my C4/Dana 20 because I kept breaking the 20s. Didn't want to buy an Atlas so 4R/205 it is... Had to build a custom cross member and shorten the rear drive shaft. Already had the edis fuel injection so just had to turn on the trans programming. Glad I went that route...