Transmission swap - C6 to AOD
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Lead Driver
Joined: Apr 2007
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From: Houston
Transmission swap - C6 to AOD
I wanted to ask for a '82 F150 with a 302, C6, and 9" diff, what kind of work am I looking at for swapping in a non computer controlled AOD?
Like wise if I swap in a AOD what rear end gearing should be used to be proper?
I really didn't want to do that as I prefer to keep a C6 but everyone keeps telling me I really need to get rid of the three speed and put a over drive in it and it will liven the truck up a whole lot without having to build a performance engine for it.
Like wise if I swap in a AOD what rear end gearing should be used to be proper?
I really didn't want to do that as I prefer to keep a C6 but everyone keeps telling me I really need to get rid of the three speed and put a over drive in it and it will liven the truck up a whole lot without having to build a performance engine for it.
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Lead Driver
Joined: Apr 2007
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From: Houston
well my big thing is drive shafts and linkage and everything. Will have to cut the drive shaft or change the yoke to swap. Or the linkage is it going to line up right, I can swap in a new prndl for the truck with OD no problem.
Mine is currently a 302, C6, 9" with a 2.92:1 or what ever it was its higher than a 3.00:1. But whats killing my acceleration and performance is the 31" tires I have over the stock 28" tires.
I was originally planning out a 331 or 347 stroker roller build with aluminum heads aftermarket cam and stock 351 CFM motorcraft 2150 carb built to be a street engine. But talking to the engine builder we use at work this past Thursday he said I just need to get rid of that C6 and get a AOD in there so I can run more gearing which will liven that engine up since 302s make their power up high not low.
Mine is currently a 302, C6, 9" with a 2.92:1 or what ever it was its higher than a 3.00:1. But whats killing my acceleration and performance is the 31" tires I have over the stock 28" tires.
I was originally planning out a 331 or 347 stroker roller build with aluminum heads aftermarket cam and stock 351 CFM motorcraft 2150 carb built to be a street engine. But talking to the engine builder we use at work this past Thursday he said I just need to get rid of that C6 and get a AOD in there so I can run more gearing which will liven that engine up since 302s make their power up high not low.
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Joined: Nov 2015
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From: Angier, NC
Back when our trucks were built is was all about MPG so that would put a low number, 3.00 or 2.47, gear in the rear axle.
Now days because of what they have learned they can put a higher number 3.25, 3/55, 3.73 gear in the axle so it will take off from a stop a lot better but then in OD it will get good MPG as the motor should be in the sweet spot.
BTW my 02 Dodge has 3.92 gears and I can tow a 5K trailer in OD at 65 MPH the sweet spot for my motor. With out trailer at 70 MPH get 15-17 MPG.
Dave ----
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Lead Driver
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From: Houston
Yep that is the thing. Ideally what I could do is do math and figure what gear I could run with a AOD so once in OD my final drive ratio would be around 2.90ish like it is right now. That way I will have faster acceleration and better performance and economy since engine isn't working so hard but also still maintain 2000 - 2500 rpm highway speeds.
But this is something I don't want to do unless its simply straight bolt in and if I decide to go back to a C6 I can swap my old one back in if I didn't like it.
But this is something I don't want to do unless its simply straight bolt in and if I decide to go back to a C6 I can swap my old one back in if I didn't like it.
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Joined: Jan 2013
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From: Tonopah, AZ
This is a handy site for playing gear ratios, axle ratios, tire sizes, rpm etc.
https://www.ringpinion.com/calculators/Calc_RPM.aspx
https://www.ringpinion.com/calculators/Calc_RPM.aspx
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Lead Driver
Joined: Apr 2007
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From: Houston
Thanks for the link. Thing is rpm doesn't match up when I put the specs in. Might not have a 2.75:1 axle ratio based off the door tag. But I remember when I cleaned off the tag on the rear axle it said 2 75. Unless the ratio was changed and the original tag was left on. But its saying with the 31" tires with a 2.75:1 with 1:1 trans ratio at 80 mph it should be almost 2500 rpm. For me I recall 2500 rpm being 75 mph for me.
But using a OD auto trans I can run a 3.25:1 axle ratio which will get me around 2000 rpm @ 80 mph.
But using a OD auto trans I can run a 3.25:1 axle ratio which will get me around 2000 rpm @ 80 mph.
Cargo Master
Joined: Aug 2007
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From: New Zealand
The driveshaft lengths are different; the shift indicator in the dash will need a swap (if you want it to be correct) but the number of positions is the same; some flexplates are ok with either trans, but some are not; the shifter linkages were also ok for my swap, but not the brackets holding them onto the transmission....they had to be modified, so did the shifter arm on the side of the trans (different lengths); the AOD will need brackets & a throttle valve cable/rod, but won't need a kickdown linkage, or modulator like the C6 uses.
In itself, the AOD won't help with performance....only a gearing change will do that.
People say that the C6 is heavier & more power-consuming than an AOD, but the AOD is in fact slightly heavier (15lb IIRC) than a C6........& I couldn't detect any performance difference between them (I did with a later manual swap). OD is obviously the big gain.
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Lead Driver
Joined: Apr 2007
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From: Houston
Thanks for the reply. If there is no performance gains to be had going with a AOD from a C6 and changing the 2.75 gears out to match the OD more properly then I will just stick with the C6 I have. Thing works great and doesn't give me any trouble. Wouldn't want to spend $1500 for a rebuilt AOD just to find out only thing Ive gained is lower rpm on the highway which really 2500 at 75 mph is not that bad for me.
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Joined: Jan 2013
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From: Tonopah, AZ
Thanks for the link. Thing is rpm doesn't match up when I put the specs in. Might not have a 2.75:1 axle ratio based off the door tag. But I remember when I cleaned off the tag on the rear axle it said 2 75. Unless the ratio was changed and the original tag was left on. But its saying with the 31" tires with a 2.75:1 with 1:1 trans ratio at 80 mph it should be almost 2500 rpm. For me I recall 2500 rpm being 75 mph for me.
But using a OD auto trans I can run a 3.25:1 axle ratio which will get me around 2000 rpm @ 80 mph.
But using a OD auto trans I can run a 3.25:1 axle ratio which will get me around 2000 rpm @ 80 mph.
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Lead Driver
Joined: Apr 2007
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From: Houston
last time I measured the tires they are 31x10.50-15 and they were just a hair over 31" but as they wear they will be at 31 and then below 31".
On the speed I verified with gps. When my needle is two needle widths below 40 I am doing 40 mph. Same for 30 and 20 ect. So if I place my needle right on 40 mph my GPS says I am actually doing 42 mph. Which is funny cause those police trailers with the speed signs that tells your speed says I am going 50 mph or more when I am sitting on 40 mph on my gauge.
On the speed I verified with gps. When my needle is two needle widths below 40 I am doing 40 mph. Same for 30 and 20 ect. So if I place my needle right on 40 mph my GPS says I am actually doing 42 mph. Which is funny cause those police trailers with the speed signs that tells your speed says I am going 50 mph or more when I am sitting on 40 mph on my gauge.
