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Technical What auto tranny

Discussion in 'Traditional Hot Rods' started by johnrfray, Nov 14, 2019.

  1. What automatic tranny are you guy s putin behind your 48 flathead truck
     
  2. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 9,214

    mgtstumpy
    Member

    Down here I've seen C4s and Toyota Cressida OD automatics. Flat attack down here also does a kit for a C4 auto. Here's the Toyota OD kit, http://www.flatattackracing.com/cressida.html

    PS Less parasitic drag with a Toyota when compared to an AOD, a C4 would be comparable to a C4 however you have OD with the Toyota auto.
    upload_2019-11-15_8-24-44.png
     
    Last edited: May 13, 2020
    anthony myrick likes this.
  3. 40Standard
    Joined: Jul 30, 2005
    Posts: 5,963

    40Standard
    Member
    from Indy

    I like a turbo 350 tranny
     
  4. FrozenMerc
    Joined: Sep 4, 2009
    Posts: 3,092

    FrozenMerc
    Member

    Hard to beat the Ford C4. Unless you are in need of an Overdrive, then the Ford AOD works well if you have a well built flathead. Most stock flatheads have a hard time pulling an OD, especially in a truck with a less than optimal drag coefficient.
     

  5. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 6,250

    Ebbsspeed
    ALLIANCE MEMBER

    I don't have a 48 flathead truck, so......
     
  6. For a automatic behind a flathead you would be hard pressed to find anything that works better than the good old C-4. HRP
     
  7. I am a big fan of the turbo 400 in a truck, but not behind a flatty. They take too much torque for a flatty to spin and still perform.

    In a flathead truck (any year) if I was going to use an automatic I would use a Ford C4. Easily adaptable to almost anything, lots of pieces to beef one up if need be, small light and not a resource hawg.
     
    Chavezk21 and 1934coupe like this.
  8. 1934coupe
    Joined: Feb 22, 2007
    Posts: 5,051

    1934coupe
    Member

    I'm a GM guy and a 400 fan but I'm also smart, if the Ford and flat head guys recommend a C4 that's what I would do in an instant. No sense in reinventing the wheel.

    Pat
     
    Chavezk21 likes this.
  9. Flathead Dave
    Joined: Mar 21, 2014
    Posts: 3,959

    Flathead Dave
    ALLIANCE MEMBER
    from So. Cal.

    C4 behind my Flathead.
     
  10. What year c4
     
  11. What year C4 ?
     
  12. Flathead Dave
    Joined: Mar 21, 2014
    Posts: 3,959

    Flathead Dave
    ALLIANCE MEMBER
    from So. Cal.

    Mine is a 1967-70

    There are a few adapter kits on the market. I purchased mine from Speedway, $400. Others are up to $800.
    Check them out to see what suits you.
     
    porknbeaner likes this.
  13. They have not really changed much since '64. I would look for a newer one just because it is more likely to have some life left in it.

    I had one in a '68 Torino that was about indestructible. I went to a big block and sold the Windsor and tranny to another guy who wore out a couple of small blocks with it.
     
  14. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 4,214

    ekimneirbo

    A few things to think about.
    When you run the large heavy duty transmissions like a 400 Turbo or comparable, they will take a lot more HP to operate and a flathead normally doesn't have excess hp to waste.

    A three speed automatic will have a higher first gear, so you may need to use a lower geared rear end to have decent acceleration......not talking race acceleration. That will in turn affect driveability if you get on the xway. Nothing is more annoying than driving somewhere with an engine running a high rpm.

    An overdrive of almost any type will give you a lower (higher numerical ) first gear, AND an overdrive gear for the xway..........making your vehicle much more pleasant and efficient.
    You get better low speed acceleration and lower cruise rpms on the xway.

    Given the lower power numbers of a flathead I think the most enjoyable transmission will be a lighter duty overdrive transmission. I think one of the biggest decisions any builder makes is what transmission he puts in the car. Many people don't want to drive to shows because they don't have good over the road capability. Take your current daily driver and get on the xway and hold it in 3rd gear for a few miles and see the difference OD makes.
    https://www.speedwaymotors.com/Flathead-V8-to-Ford-AOD-Transmission-Conversion-Kit,25353.html

    Looks like an easy to make adapter or can probably buy just an adapter if you can get your own tranny.
     
    Last edited: Nov 16, 2019
  15. I'm considering going down this auto road more and more and am curious to know who has successfully used the Ford AOD or the Cressida AOD and what chassis mods were required?
     
  16. C4s in both the truck and FED. rebuilt right here in own garage.........did use Flat-O-Matics torque converter and adapter kits though.....
     

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