C6 to AOD swap - F150online Forums

Pre-1997 Models

C6 to AOD swap


Old 04-26-2007, 07:33 AM
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C6 to AOD swap

How do you guys feel on a swap like this? I understand that the AOD is not nearly as strong as the C6, but I dont tow or anything like that. I just feel as if the C6 is killing my gas mileage since its a 3-speed. Right now my truck is pretty bulletproof it seems with the 300 along with the C6.

I dont think It would be to hard of a swap, the AOD isnt electronicly controlled. What all is needed for the swap?

So basically, the only reason I would be doing this is to help my gas mileage. I get 11 around town, and 14-15 on the highway. On the highway, this thing screams especially with the 300, which isnt a high rever. Also I have 2.73 gears.
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Old 04-26-2007, 07:41 AM
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With 2.73 gears, the AOD may not give you what you're looking for. With a 0.67:1 OD you're only going to be turning about 1400 RPM at 65 MPH. That's a bit too low and may cause the engine to lug. If any engine can work at that kind of RPM it's a 300, but I doubt it
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Old 04-26-2007, 07:53 PM
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I was curious about my whole RPMs thing, so today I checked what I am currently at. At 65 mph I am turning about 2200-2300 RPMs. If the 300 could work at 1400 rpms, is there a significant difference of gas consumption between 2300 and 1400 rpms?

I dont know if this matters or not, but I have 31" tires also.
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Old 04-26-2007, 09:09 PM
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It matters.
That 1400 figure (actually 1420) was for 29" tires which roll at about 722/mile. Your 31s roll at more like 680/mile so at 65 you're going to be turning about 1350 RPM. I strongly suspect that you're below the point where your 300 is going to deliver either drivability or economy, but I may be wrong.

My 96 with the original 3.08 gears and an E4OD (0.71:1 OD) and stock tires turned 1685 at 65. It delivered 19.5 MPG highway but it had some drivability issues (downshifting too much because of not enough gear or lugging if it failed to downshift.) Your taller gears and the dlightly taller OD of the AOD would be worse and might not return equivalent fuel economy.

EDIT: either your tach or your speedo is off; at 65 you should only be turning a skosh over 2000 with those tires

Last edited by StrangeRanger; 04-26-2007 at 09:40 PM.
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Old 04-27-2007, 09:45 PM
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Between the "highway gears", the AOD's deep overdrive, and the larger tires you may get better mileage, but get to 60 sometime within 10 minutes. The 300 is a torquey motor, but that's asking quite a bit. Don't even think about hauling.

Lugging around with the pedal floored will not save any gas versus an easy cruise at a higher RPM. It will also put a lot more wear and tear on the motor from the constant max load. Even the slightest incline would cause a downshift since the motor would immediately bog down, bringing your revs up.

My old truck with a 300 and a 5-speed and 3.08 gears would average around 16mpg straight highway, closer to 9 or 10 around town. That manual had a .8:1 overdrive gear. It didn't have a tach, but I'd guess revs were somewhere around 2200 or so at highway speeds.

I doubt you would get much of a MPG increase with the swap. You're trading revs(hp) for "lug"(torque).

If you're looking to get a more fuel efficient vehicle, either look into a newer used truck possibly with the 4.6 or if you need a commuter some used econobox just to run to work and back. You can swap and tune one of those trucks all day long, but you're never going to get good mileage. They're big trucks with big motors, sucking gas comes with the territory.
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Old 04-28-2007, 10:13 AM
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You guys all brought up points that I never even thought about. I guess that idea is out the door, ill just have to suck it up and deal with the gas mileage. I could never get rid of this truck. I have had it since I was 15, I am now 20 and it runs the same it did then. Thanks alot
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Old 04-28-2007, 12:09 PM
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If you are in the mood to do a bit more work...

1) Put in the AOD and see if it works for you. It may just be what you're after. BTW, the adjustment of the "TV cable" is critical on the AOD; if you get it wrong, the tranny will burn up in minutes. Get a good shop manual on the care, feeding and adjustment of the beast before you attempt the swap.

2) If the swap doesn't do what you want, swap your ring and pinion to a numerically higher ratio. I'd guess that a 3.27 or possibly 3.55 would give you both the fuel economy that you're after and a nice boost in performance. Cruising RPM @ 65:

Your present setup: 2010
Swap in the AOD: 1350
Change R&P to 3.08: 1520
Change R&P to 3.27: 1615
Change R&P to 3.55: 1750
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Old 05-01-2007, 06:00 AM
Join Date: Sep 2005
Location: Murfreesboro, TN
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If you have th 2.73s stick with the C-6 or if you have your heart set on teh AOD, get at least a 3.27 gear to keep some towability.....
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