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1950 ford speedo to turbo 400 trans?

Discussion in 'The Hokey Ass Message Board' started by bamboozelor, Mar 29, 2011.

  1. bamboozelor
    Joined: Dec 10, 2008
    Posts: 24


    is it possible to make the speedo work? I've searched the net for hours and found nothing. I have a 1950 ford 4 door with a turbo 400 trans. Is there a cable made to mate the 2? any tricks anyone knows?
  2. badshifter
    Joined: Apr 28, 2006
    Posts: 3,293


    You have to get one made. You will have to run a gear reducer in between to correct the speed reading. The drive on the chevy spins faster than the speedo of the ford. I had North Hollywood Speedometer do mine locally for my 50 Ford. Check if you have any local speedo shops in your area.
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 47,499


    how about using a chevy cable? Doesn't the speedo end use the standard 5/8" threaded fitting? I could be wrong about this, but I'd look into the easy way first.

    And you can either get a ratio adapter, or put the right gears in the trans so you don't need the adapter. They all work on 1000 revs per mile, you can find the gear info on the TCI transmission web page
  4. e1956v
    Joined: Sep 29, 2009
    Posts: 1,622

    Alliance Vendor

    Speedometer end is standard 5/8s 18, trans end 7/8s 18. Call a local speedo shop and you can have one made just give them the length you need.

  5. ericl1951
    Joined: Nov 16, 2009
    Posts: 84


    What you need is Napa # 615-1606 BK. or try pioneer CA-3004 (might be cheaper).
  6. yes , CA 3004 for a 83" long cable
  7. bamboozelor
    Joined: Dec 10, 2008
    Posts: 24


    AWESOME!!!!!!! thanks guys!!!
    I'm going to try the ca3004 first. at first I don't care if it reads exactly correct the car is still a primered turd anyways. I'll just have someone tell me when I'm going 60 and see what the speedo reads there then go off that.
    then when I fix everything else I'll look into making it read correct (if the speedo still works?)
  8. like squirrel said I went to NAPA & got a cable the Lenght I wanted
    to hook up to my 50 Merc & Powerglide Trans
    and if there is a Trans Shop near by he can set you up with the right trans Gears
    Just my 3.5 cents
  9. bamboozelor
    Joined: Dec 10, 2008
    Posts: 24


    anone know how to figure out which drive gear is in the trans without removing the tailshaft?
    and ideas what factory rear end gears I have int a 50 ford 4 door sedan that originally came with a flathead 8 and 3 on the tree?

    I don't need the speedo exact but it would be nicer it it was a bit closer. right now it reads 70 MPH at about 50-55
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 47,499


    you might be able to count the teeth on the drive gear, jack up the vehicle, put the rearend on stands, then pull the driven gear and sleeve out of the trans. wipe off the drive gear as best you can, put a mark on one tooth with a sharpie. put it in neutral, turn the driveshaft slowly and count teeth till you get back to your mark.

    The metal gears are pressed on, it's fun pulling them, the special puller helps. The plastic gears are held in with a spring clip. Early 400s used the metal gears, later ones used plastic.

    also the driven gears are not all the same size, the sleeve has number on it for which gears it fits, like 33 34 35 36 or something. been a while since I looked at one. If you need a driven gear that has more teeth than the sleeve you have, you'll need the right sleeve for it.

    The easy way out might be to get a ratio adapter, use the odometer and GPS or interstate mile markers to figure out how far it's off.
  11. Deuce Roadster
    Joined: Sep 8, 2002
    Posts: 9,519

    Deuce Roadster
    Member Emeritus

    Pull the speedometer bullet and check the color of the gear on the output shaft.


    They are color coded ... as are the driven gears


    7 teeth - pink 18 teeth - brown
    8 teeth - black 19 teeth - natural
    9 teeth - green 20 teeth - blue
    10 teeth - red or purple 21 teeth - red
    17 teeth - red 22 teeth - gray
    18 teeth - blue 34 teeth - light green
    19 teeth - yellow 35 teeth - orange/pink
    20 teeth - brown 36 teeth - white

    37 teeth - red
    38 teeth - blue
    39 teeth - brown
    40 teeth - black
    41 teeth - yellow
    42 teeth - green
    43 teeth - purple
    44 teeth - dark gray
    45 teeth - light blue

  12. Super Chevy, Oct. 1989 had the chart to figure all this out. It was on the web 10-12 years back, when i printed it. Might still be there...
    Briefly, the formula is thus:
    Multiply the rear axle ratio by 20.2.
    Divide by tire diameter.
    Then look up the number on the loooooong chart, which I have here.
    Install gears.


    P.S. HOLY SHIT!!!! It's still out there!!!
    Go here.
  13. bamboozelor
    Joined: Dec 10, 2008
    Posts: 24


    I guess I should probably figure out my rear axle ratio first. ERRRgh. mark tire and driveshaft spin and count right? anyone know the stock ratios possible for a stock 1950 ford rear end that came with a 3 speed standard and a flathead V8?
  14. squirrel
    Joined: Sep 23, 2004
    Posts: 47,499


    There are two ways to go about this, one is to figure out the gear ratio, tire size, and do the math. The other is to see how far off it is, and use a percentage difference to fix the error.

    Jack up one rear wheel, mark the driveshaft, turn the wheel twice (exactly) and count the driveshaft revolutions. Probably somewhere around 3.7 to 4.1

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