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9inch and flathead with original tranny?

Discussion in 'The Hokey Ass Message Board' started by hotrod-kenny, Oct 19, 2008.

  1. hotrod-kenny
    Joined: Oct 16, 2007
    Posts: 270

    hotrod-kenny

    Hi Does any of you guys use a flathead, original trans and modern style rear axle? what ratios do you run? what did you do with the torque tube?

    I have a 46 ford coupe with a french flathead 46 trans and banjo with 3.55:1 ratio. But I still want to get better highway speed and low rpm. Thinking about using a 8" or a 9" ( or some GM axle ) with like a 2.90:1 or something.

    When i Changed from 3.71:1 to 3.55:1 I noticed a small difference in rpm at higway speed and 1 st gear is still useable for cruising. But i want lower rpm still.

    I know a t-5 would be the best way to go, but we dont have a lot of them here in Norway, and just changing the axle would be easier and cheaper.
     
  2. R Pope
    Joined: Jan 23, 2006
    Posts: 3,310

    R Pope
    Member

    To keep the '46 trans you need the tailpiece off a pickup, it converts to an open drive.
     
  3. lowsquire
    Joined: Feb 21, 2002
    Posts: 2,564

    lowsquire
    Member
    from Austin, TX

    9 inches absorb quite a few of your precious flathead hp as well..
     
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  4. Use a larger diameter rear tire!!!!!!!!
     
  5. d_Seymour
    Joined: Sep 28, 2006
    Posts: 75

    d_Seymour
    ALLIANCE MEMBER
    from Michigan

    Find a nice T5 transmission
     
  6. hotrod-kenny
    Joined: Oct 16, 2007
    Posts: 270

    hotrod-kenny

    ok. thanks guys.
     
  7. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,410

    Flat Ernie
    Tech Editor

    You have many options.

    You can convert both your early Ford tranny & banjo to open drive, but that gains you nothing but a driveshaft & new rear suspension.

    You can convert your early Ford tranny to open drive and swap in an 8" or 9" and new rear suspension.

    You can convert your banjo to open drive and swap in a T5 (best choice, IMO).

    You can run taller tires (won't gain much RPM reduction).

    When you go to open drive, you will have to redesign the rear suspension. W/O the torque-tube, something else must take the rotational force of the rear - either parallel leafs or some sort of linkage.
     
  8. sidevalveguru
    Joined: Nov 1, 2008
    Posts: 56

    sidevalveguru
    Member

    Are GM 10-bolts common there?
    Should be strong enough, & consume less power to turn.
    Downside is that crownwheel changes must be made in the housing.
     
  9. Retrorod
    Joined: Jan 25, 2006
    Posts: 1,998

    Retrorod
    Member

    We run a 3.00 gear in our 8BA roadster on 28" tires...originally with the Ford three speed, it's a light car and that ratio seemed to be just fine. Since we changed to the T-5 a year ago we are satisfied that the 3.00 is still the perfect ratio even with the overdrive. The car will cruise all day long at 65 mph. That '46 is a lot heavier so I would think that maybe about 3.25 might be better.....the 3.00 would be a bit much.
     
  10. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,208

    Shaggy
    Member
    from Sultan, WA

    Time for a Quickchange!!
     

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