C4,C5 or AOD which do you prefer?

Reply Subscribe

Thread Tools

Search this Thread

Jan 16, 2005 | 02:21 PM

desertdave35

Thread Starter

More Turbo

Joined: Oct 2004

Posts: 621

Likes: 2

From: Marana, AZ

C4,C5 or AOD which do you prefer?

I have a 1970 F-100 with a 302 and a C-4 tranny. When the engine is done it will be putting out 275+ HP. I want a good solid tranny that will hold up. I've contimplated using the C-5 or AOD because of the overdrive abilities to save on gas when I cruise long distance. Or do I just rebuild the C-4 that I have. I heard that in 1970 they changed the C-4 to a larger sline input shaft and is stronger than the earlier C-4 models. Do we have any tranny builders here who can testify to what is the best way to go?

Jan 16, 2005 | 03:48 PM

ATC_250SX

Posting Guru

Joined: Nov 2003

Posts: 1,071

Likes: 1

From: Concord, New Hampshire

I would go with a C-6, maby new or rebuilt, or a junkyard one, there supposed to be the strongest automatic ford tranny, and ive heard that there bullet proof, but as for the A0D, never heard much good about them, along with the E40D, and ive never heard of a c-5.

Jan 16, 2005 | 04:26 PM

desertdave35

Thread Starter

More Turbo

Joined: Oct 2004

Posts: 621

Likes: 2

From: Marana, AZ

I thought about the C6 but doesn't have the overdrive option that I'm looking to get.

C5: This transmission was used from 1982 to 1986 in both the Rangers and F-series pickups. The case length and gear ratio is the same as the C4, except the oil pan on the C5 has a hump in it and the oil pan for the C4 is flat.

Jan 16, 2005 | 05:30 PM

ATC_250SX

Posting Guru

Joined: Nov 2003

Posts: 1,071

Likes: 1

From: Concord, New Hampshire

well Dose the c-4 have an OD option? i was just thinking the c-6 because of the durability of the tranny, Thats what i have in my 87 f-150 and i love the thing, tows great, and loves the backroads, not to bad on the interstate but OD would be nice.

and thanks for letting me know about the c-5, i guess you learn new things everyday.

Jan 16, 2005 | 08:00 PM

hdgapeach

Elder User

Joined: Jan 2004

Posts: 767

Likes: 1

From: Franklin, GA

The only way I know of to gain overdrive with a C4, C5 or a C6 is to purchase one of those aftermarket overdrive units and add it on behind the tranny, mucho dollars and more, with the driveshaft modifications. A C4 assembled with quality parts can be built to hold up to around 450hp. Same for the C6 up to nearly 700hp. Don't know of anyone, nor have I read any literature concerning beefing up a C5, but I have "heard" plenty of negative comments concerning it. If you truley want an overdrive, swapping in an overdrive tranny with adaptions to make it fit would be the way to go, simpler and more economic. (Just my opinion, of course.)

Jan 17, 2005 | 05:15 AM

desertdave35

Thread Starter

More Turbo

Joined: Oct 2004

Posts: 621

Likes: 2

From: Marana, AZ

I know I will not get the overdrive option with the C4, But to my understanding, correct me if I'm wrong, the C5 has a lockout torque convertor, which in a sense is like having overdrive isn't it? I know the C5 was introduced as the improved C4 with better oiling capabilities and a bigger torque convertor. Then the AOD was supposed to be the improvement over the C5. I guess what my questions is which tranny would be the choice of you muscle car owners, would it be worth it to sacrifice a little power for the overdrive in the AOD or just stick with what I got and keep the 26 spline C4 and give it a stage 3 shift improvement.

Jan 17, 2005 | 08:07 PM

SoCalDesertRider

Postmaster

Joined: Dec 2002

Posts: 3,959

Likes: 9

From: USA

The torque converter lock-up of the C5 is only worth about 300 rpm drop versus your C4 if the torque converter in your C4 is good. The AOD has a 0.67 overdrive ratio, which is really high. At 65 mph, the rpm drop would be about 880 rpm with a 0.67 overdrive ratio, assuming a 3.55 axle ratio and 29" tires. If you want lower rpms at higher speeds, the AOD is the way to go. You can also build the AOD with a lower first and second gear from the later model AODE/4R70W, which is 2.84/1.55 -vs- 2.40/1.47 stock for the AOD and 2.46/1.46 for the C4, so you get more torque for pulling from a stop as well as lower rpms at cruise once it shifts into overdrive. The lower ratio gear sets are available from Ford Racing and Sumitt Racing. They sell lower ratio gear sets for the C6 as well. 3rd gear is left unchanged, 1.00:1, in all the autos. Assuming you will be building whichever trans you put in, the AOD would be a good one to build because of the overdrive. I don't think I'd bother with the C5 if you already have a C4. For a non-overdrive auto, I would build a C6 for it, although the C4 may be fine with it.