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Technical '39 ford tranny

Discussion in 'Traditional Hot Rods' started by arvonian, Sep 7, 2013.

  1. arvonian
    Joined: Feb 28, 2013
    Posts: 35

    arvonian
    Member
    from Virginia

    Is there any quick way to tell the difference between a '38 and '39 tranny?
    I was told that the 39 has a stronger case than the 38... One advertized locally as a '39, but would like to be able to verify if I go to look at it.
     
  2. 117harv
    Joined: Nov 12, 2009
    Posts: 6,590

    117harv
    Member

  3. George/Maine
    Joined: Jan 6, 2011
    Posts: 949

    George/Maine
    Member

    The 39 and truck tower will have a 3" fork, the gears are weak not the case.
     
  4. arvonian
    Joined: Feb 28, 2013
    Posts: 35

    arvonian
    Member
    from Virginia

    Thanks guys, this FNG still hasn't found the easy button (search!):confused:
     

  5. The cases are the same. Both years will have a "78" on the case showing it was first used in 1937. The important difference is in the gears. To complicate maters some '39 used the '38 gears so can't just go by the serial number, you need to be sure you get the desired gears and tower. If it is supposed to be a "39, do a search to learn how to identify the correct gears and tower. You can probably find the information you need at http://www.vanpeltsales.com/FH_web/flathead_home.htm

    Charlie Stephens
     
    Last edited: Sep 7, 2013
  6. Andy
    Joined: Nov 17, 2002
    Posts: 4,765

    Andy
    Member

    Take the top off and look at the sychro coller. If the fork groove is at the rear, it has 39 type gears. The top should be marked 81-xxxxx for the interlock style.
     
  7. flatford39
    Joined: Dec 3, 2006
    Posts: 2,800

    flatford39
    Member

    I have a few 78 cases and a recently rebuilt 46 48 transmission. I am going to put those gears into my 78 case as they will be an upgrade because of synchros etc from the 37 39 gears. I am doing this because I want a top shifter. You will need the #81 top shifter with the 3" forks to make this work.
     
  8. arvonian
    Joined: Feb 28, 2013
    Posts: 35

    arvonian
    Member
    from Virginia

    I'm thinking this internet thing just might catch on! Thanks for all of the info.
    Checked my '38 trans., 78-7006 case and 81A-7222 shifter housing. So, I'm thinking that the '39 gears would be an upgrade due to the improved synchros?
     
  9. Dynaflash_8
    Joined: Sep 24, 2008
    Posts: 3,023

    Dynaflash_8
    Member
    from Auburn WA

    Now to throw a wrench in, I put 46 6 cylinder gears in my 39 case.



    Posted using the Full Custom H.A.M.B. App!
     
  10. Carter
    Joined: Mar 18, 2006
    Posts: 1,440

    Carter
    Member

    Pull the top and measure the big fork. If it's 3", you've got the 91A fork and later synchro. If it's 2 7/8", you don't.
    I've never felt it was such a huge deal. Ford three speeds were synchronized on the 2-3 shift from 32 on. The synchro and shifter housing were improved a few times between then and 39, but I always wondered if it was really that big of a deal. I'd imagine a worn out 39 box would shift just as terribly as a worn out 34 box.
    I don't have much trouble shifting the stock gearedB trans in my A.

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  11. 1941coupe
    Joined: Jul 4, 2010
    Posts: 401

    1941coupe
    Member


    the early forks are 2 3/4 later 39 up have 3" forks also the double detent plugs are 5/8 as per mac van pelt site,
     
  12. Carter
    Joined: Mar 18, 2006
    Posts: 1,440

    Carter
    Member

    The 81A top is double detent. Prior to that they were single detent(not counting V8-60). Not all 81A tops have the 3" fork, though.

    Posted using the Full Custom H.A.M.B. App!
     
  13. My '40 coupe has a '40 p/u transmission. Any difference between the '39 pass car and '40 p/u trans.
     
  14. Andy
    Joined: Nov 17, 2002
    Posts: 4,765

    Andy
    Member

    Clutch release shaft different.
     
  15. Fortunateson
    Joined: Apr 30, 2012
    Posts: 4,137

    Fortunateson
    Member

    I have a '46-48 truck tranny and a '40 car tranny with Zephyr gears. Will swappy the Zephyr gears into the truck tranny case be a big deal? It;s going into a '32 5 window with a '40 rear end. I hope the only real big deal will be converting the rear end to open drive or can the '40 torque tube attatchment be used on the 'truck tranny ?
     
  16. Fortunateson
    Joined: Apr 30, 2012
    Posts: 4,137

    Fortunateson
    Member

  17. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    Pretty much all of what you need to buy the right stuff is in this old post: I tore all the tips out of "Consumer's Guide."

    http://www.jalopyjournal.com/forum/showthread.php?t=91515&highlight=39+trans+prices&showall=1

    When talking about the ""39 trans", always be aware that roughly half of TRUE ones, the ones out there with an actual '39 serial number, had the '36-38 type innards and not the late synchro/big fork, and that the type of trans everyone actuall wants can be built out of a wide variety of Ford parts of different years.
     
  18. Andy
    Joined: Nov 17, 2002
    Posts: 4,765

    Andy
    Member

    Also, the true 39 box had a unique clutch arm. It is designed to be used with the odd 39 pedals. I have a dimension hid somewhere if somebody need it.
     
  19. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    Most actual uses will require arm change and change of rear mount to fit chassis in question, and in a tight cockpit like a Model A choice (or bending) of shift lever may be critical.
     
  20. gasheat
    Joined: Nov 7, 2005
    Posts: 714

    gasheat
    Member
    from Dallas

    My friend Andy is a smart guy.
     

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