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Thread: Where to start for manual to auto conversion

  1. #1

    Default Where to start for manual to auto conversion

    I'm thinking of making the swap from manual to auto. I knew deep down I should have just waited to find an auto bronco, but I fell in love with a 3 speed manual (before driving it). Is this a complicated swap? I see C4 trannys on CL but they aren't from broncos. Whats the best way to go about this? Currently have 3.50 gears, 33s, stock 302. Way down the road, I plan on re-gearing to 4.11s and 35s. This will be a street bronco. What is the best auto tranny for my setup, and what's the easiest way to accomplish? Budget is around 1500-2000, and that would include a shop doing it. I'm sure there are ways to cut costs, but if ease of finding parts and reliability is effected, I don't mind spending more. Thanks!

  2. #2
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    Default Re: Where to start for manual to auto conversion

    C4 is probably the easiest, but I hear good things about the AOD. Being a mostly street rig, overdrive is nice.
    1970 Bronco
    My build thread

  3. #3
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    Default Re: Where to start for manual to auto conversion

    You need to swap the pedal assembly and you can either swap in an auto transmission steering column or install a floor shifter for the auto. If you go with the floor shifter there are a couple things you can do to ditch the 3 on the tree shifter that's on the column now.
    1975 Ford Bronco: 105" wheelbase, King 14" c/o shocks, King 2" air bumps w/ Duff arms, 4 link rear w/ coils. Fuel injected 408W, ZF 5 speed/NP 205 and Dana 60/70 axles with 5.13 gears and ARB's, 41.5/13.5R17 Pitbull Rockers on 17" Raceline Monsters.

  4. #4
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    Default Re: Where to start for manual to auto conversion

    Just an fyi, Chip,our host for the spring bash on the 21st has a complete C4 setup that he just pulled out of his Bronco. The 289 and C4 are being replaced with a John Deere and NV4500. he's asking around $600 for it, complete motor plate to t/c adapt.
    72 sport/exp.,TBI 302,NP435,4.56 Powrlok/ARB in Full Width's.5.5" CAGE lift w/arms,2'' bl,37's, rescued from the concrete jungle (L.A.) NEVER DONE!!! Sold to buy a Boat, Now Broncoless.....Ah wait, 79 in the boneyard, does that count??
    Now it's fast water,smooth women and cold beer!!

    ALL MY DRINKING BUDDIES HAVE A SEVERE BRONCO PROBLEM !!!


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  5. #5

    Default Re: Where to start for manual to auto conversion

    You don't need to swap the pedal assembly. You can remove the clutch pedal pretty easily. If you do a floor shifter, it's also easy to remove the column shifter. A C4 from a Bronco will be the easiest and cheapest swap.

  6. #6
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    Default Re: Where to start for manual to auto conversion

    Quote Originally Posted by gddyap View Post
    You don't need to swap the pedal assembly. You can remove the clutch pedal pretty easily. If you do a floor shifter, it's also easy to remove the column shifter. A C4 from a Bronco will be the easiest and cheapest swap.
    I changed my 77 from an auto to a manual (5spd)... My nieghbor down the street wanted an auto instead of a manual... we traded straight across. Looks like you have a list of parts already from your Classic thread. What Gil said above is the best way to go.

    POPS that is a screaming deal from Chip...
    Last edited by 904Bronco; 04-13-2012 at 09:55 AM.
    1968 Plain Jane Lubr, Explorer EDIS EFI, 4R70W, a daily driver!
    2009 Grabber Orange Mustang GT for fun!
    1971 Project Bronco.....

  7. #7
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    Default Re: Where to start for manual to auto conversion

    I would do an overdrive. You will never regret it. I personally would spend the money for a 4R70W (AODE) from a 5.0 ford Explorer and couple it with a Baumann Optishift controller. By far not the cheapest solution, but one of the best since you can hook a lap top to it and customize it to your liking. Longer transmission which puts the transfer case back 4 or so inches. Some report needing a 1" body lift. Some clearance the floor, but with as clean as your rig is I wouldn't do it. I plan do machine a 1" body lift down to 1/2-5/8, trim the cross member that hits transfer case. And since I need a custom trans mount anyway, I also plan to lower the trans a little too. I just don't want a 1" body lift with stock bumpers. Driveline modifications needed also.

    A middle option is the AOD. Its not electronically controlled and uses a TV (throttle velocity) cable attache to the carb linkage. If this isn't adjusted peoperly you will fry the trans. Longer trans too requiring same mod as above.

    If you are looking to do it on the cheap, then the C4 package is the way to go but I bet you will wish you had the overdrive. This is a bolt in swap.

    You will also need a floor shifter or a shifter column for all the options listed.
    I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it. TJ

  8. #8
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    Default Re: Where to start for manual to auto conversion

    Quote Originally Posted by gddyap View Post
    You don't need to swap the pedal assembly. You can remove the clutch pedal pretty easily.
    Or you could just cut it off with a zip wheel.
    I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it. TJ

  9. #9

    Default Re: Where to start for manual to auto conversion

    Quote Originally Posted by Delta 4 Wheel View Post
    I would do an overdrive. You will never regret it. I personally would spend the money for a 4R70W (AODE) from a 5.0 ford Explorer and couple it with a Baumann Optishift controller. By far not the cheapest solution, but one of the best since you can hook a lap top to it and customize it to your liking. Longer transmission which puts the transfer case back 4 or so inches. Some report needing a 1" body lift. Some clearance the floor, but with as clean as your rig is I wouldn't do it. I plan do machine a 1" body lift down to 1/2-5/8, trim the cross member that hits transfer case. And since I need a custom trans mount anyway, I also plan to lower the trans a little too. I just don't want a 1" body lift with stock bumpers. Driveline modifications needed also.

    A middle option is the AOD. Its not electronically controlled and uses a TV (throttle velocity) cable attache to the carb linkage. If this isn't adjusted peoperly you will fry the trans. Longer trans too requiring same mod as above.

    If you are looking to do it on the cheap, then the C4 package is the way to go but I bet you will wish you had the overdrive. This is a bolt in swap.

    You will also need a floor shifter or a shifter column for all the options listed.
    Thanks guys. If my plan is to go 4.11s and 35s, would I benefit from overdrive? I'm still learning all the gear stuff, but my understanding is that setup is like stock. Keep in mind this is a street bronco rarely going above 60-65. Plus I'm looking to keep it as close as 2K in cost as possible and that's including labor.

    Hey POPS, that does seem like a great deal... I have to work on the day of the bash, how to I get ahold of Chip? Thanks!

    Still entertaining the idea of overdrive...

  10. #10

    Default Re: Where to start for manual to auto conversion

    Quote Originally Posted by gddyap View Post
    You don't need to swap the pedal assembly. You can remove the clutch pedal pretty easily. If you do a floor shifter, it's also easy to remove the column shifter. A C4 from a Bronco will be the easiest and cheapest swap.
    Hey, that pedal piviot shaft can be stuck in there for life! I've hung off my press trying to get them out before giving up and cutting them off.
    So far I'm 2 out of 3 I've had to cut off.
    Mark Harris
    71 Bronco, 9 inch, 60, c4, Stak 3 speed, and 42 inch balloons.

  11. #11

    Default Re: Where to start for manual to auto conversion

    Hey guys- been reading a lot about the 4r70w. Seems likes it's a lot of work with extra parts, but well worth it. Realistically, how much $ would it take including labor?
    Last edited by guidoverduci; 04-13-2012 at 07:28 PM.

  12. #12
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    Default Re: Where to start for manual to auto conversion

    Quote Originally Posted by guidoverduci View Post
    Thanks guys. If my plan is to go 4.11s and 35s, would I benefit from overdrive? I'm still learning all the gear stuff, but my understanding is that setup is like stock. Keep in mind this is a street bronco rarely going above 60-65. .
    With that setup at 65 you would be at about 2165 rpms (higher with converter slippage). With and AOD overdrive ratio of .67 that would put you at about 1450 before slippage. All I know is 1450 rpms will be a lot more quiet inside rig!

    What I would do (even if it means saving more money for longer) is get 4.56's or 4.88's with an overdrive. That thing would kick ass.
    I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it. TJ

  13. #13

    Default Re: Where to start for manual to auto conversion

    Also...Can someone chime in on what the C4 is like with 33s and 3.50 gears, or 35s and 4.11s... Stock 302. How's the power, fun to drive still or sluggish? RPM range when cruising 60-65 or city driving? Reason I'm asking is I've been reading threads that say go 4r70w over C4 and do it right the first time but I'm assuming at least double the cost, Is the c4 really that bad?

  14. #14
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    Default Re: Where to start for manual to auto conversion

    Quote Originally Posted by guidoverduci View Post
    Also...Can someone chime in on what the C4 is like with 33s and 3.50 gears, or 35s and 4.11s... Stock 302. How's the power, fun to drive still or sluggish? RPM range when cruising 60-65 or city driving? Reason I'm asking is I've been reading threads that say go 4r70w over C4 and do it right the first time but I'm assuming at least double the cost, Is the c4 really that bad?
    A tired stock 203 will suck but I think your rig looks fresh. It will run better with 4.56 gears for sure.

    http://www.wildhorses4x4.com/categor...o_Transmission

    Do the math yourself for any combination with the chart above and this list. I'd do it for you, but I have had a few Pale Ales.
    I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it. TJ

  15. #15
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    Default Re: Where to start for manual to auto conversion

    Quote Originally Posted by guidoverduci View Post
    Also...Can someone chime in on what the C4 is like with 33s and 3.50 gears, or 35s and 4.11s... Stock 302. How's the power, fun to drive still or sluggish? RPM range when cruising 60-65 or city driving? Reason I'm asking is I've been reading threads that say go 4r70w over C4 and do it right the first time but I'm assuming at least double the cost, Is the c4 really that bad?
    No the C4 is not that bad, it is a bomb proof small block tranny... But it does not have an overdrive and these trucks were built when gas was cheap and the hwy RPM's will be high.
    If you do an AOD then you need to find a tranny, take it apart (say rebuild) to replace the rear output shaft with the $700.00+ dollar AA kit. Then you need to hook up the gear shifter somehow (floor or column) and connect the TVS cable to the Carb. Do not forget adding a tranny cooler and running the lines, redoing the driveshafts, maybe rebuilding the D20, use an auto tranny starter, find cover plate, flex plate, etc. This will be specialized labor, someone who understands Broncos and transmissions.

    As far as the 4r70w, maybe someone can chime in on that cost...

    You have stated that you are not mechanical and a new Bronco owner, so you will have to pay an hourly rate for someone to do all this work. That is what is going to drive up the cost of your project.

    How about driving the summer with the three speed, enjoy the Bronco, fix the little things. Continue to research this change, make a plan, chase down parts, save money, and make changes next winter. Sorry for the unsolicted .02

    Doug
    Last edited by 904Bronco; 04-13-2012 at 09:02 PM.
    1968 Plain Jane Lubr, Explorer EDIS EFI, 4R70W, a daily driver!
    2009 Grabber Orange Mustang GT for fun!
    1971 Project Bronco.....

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