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Technical What gear?

Discussion in 'The Hokey Ass Message Board' started by Darin Younce, Jul 21, 2020.

  1. Probably been a subject discussed bunches but I will be working on my Banjo rear for my 39 ford pickup with 3 speed top loader , and am wondering if anyone on here has ran a 325 or 3.54gear , and how it worked out. I have yet to determine my current gear but 38 ford pickup had 3.78 or optional 4.11 , not sure about 39 though. Have looked for the gear ratio stamping but just cant see it. Will really search later today. i just want a little more highway speed, not intending to run on interstate .
     
  2. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    rear tire size info will help
    my truck had 355s and standard 3spd
    235 75 15 tires
    55-60 was no problem.
     
  3. ^^^^^ Excellent advice there. Really, how much faster do you want to go in an old truck that was designed to travel on roads that were 60% dirt in the rural areas? The paved roads were not designed for the speeds capable of by modern vehicles with independent suspension and radial tires.
     
  4. anthony myrick
    Joined: Sep 4, 2009
    Posts: 5,930

    anthony myrick
    Member

    gear ratio.jpg
    this might help a little
    I could run 65 down the interstate with the 355s but I didnt feel it was healthy much past that for long periods
    it seemed to be happy in that 55 - 60 range
    this was a 235 straight 6 in a gm truck
    but the same should apply to your application
     
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  5. I try to run a 3.25 to a 3.55 in most of my cars that I drive. A lot depends on how much torque you got and how many revs you like to turn. I try to convince people that if you drive a car daily and your final drive is 1:1 you really don't want to go much deeper that a 3.75:1 gear and with that you have to enjoy 3K plus in the rev dept on the highway.
     
    warbird1, vtx1800 and anthony myrick like this.
  6. Thanks, I have 235 75 16 rear tires and I am at pretty high revs at around 50 mph ( per gps)
     
  7. What do you consider pretty high revs? It is noisier than your late model or you have actual tachometer readings?
     
  8. Never said I wanted speeds capable of modern cars , I said I wanted a LITTLE more speed . rarely go over speed limit in my modern vehicles
     
    warhorseracing likes this.
  9. Thanks, exactly the type answer I was seeking.
     
  10. Well it is certainly noisier that my my late model and that is not my reference point and I have no tach . have worked on cars for 45 years and just know the engine is at higher revs that I it needs ( and I want it to be) to be at 50 mph.
     
  11. Thanks , that's all I want around 55 and a little less rpms.
     
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  12. squirrel
    Joined: Sep 23, 2004
    Posts: 46,425

    squirrel
    Member

    you can guess....or you can figure it out.

    How fast are you driving when the engine is comfortable? 50? Figure out what gears you have now, and change the ratio by the same percentage, as you want to increase your speed.

    But keep in mind that acceleration and hill climbing will be affected.
     
  13. Work In Progress
    Joined: Dec 14, 2010
    Posts: 153

    Work In Progress
    Member

    I run a 3.0 gear in my flathead powered 49 Dodge but I also have a 26" rear tire. It works out to about a 15-20% taller gear than the original 3.91 and 28"ish tire. Can run 70 but it seems much happier running 65. Acceleration is still acceptable even with the fluid drive/3 speed. Engine is a stock, semi fresh 230 with dual webbers and headers. I drive this car a lot and get 17-20 mpg on average so it's not working too hard.
     
    Last edited: Jul 21, 2020
  14. Thanks, Actually it seems pretty comfortable at around 47 or so , I might be a bit conservative on what I call comfortable but I know from years experience of driving everything including class 8 commercial trucks what is a high rev vs a comfortable rev . I have looked for the stamping on the housing once or twice for my ratio , just gotta get under there and really look. had a crazy Idea of trying to look thru the fill hole and marking one gear with some marking compound and rotating and counting teeth but honestly that might be an impossible task although I can see the ring gear when I remove the plug.
     
  15. I will be ordering some wide whites in the near future and think ( not sure) the rears will be around 29" tall. I f I get a comfortable drive at 55 to 58, I will be happy.
     
  16. Work In Progress
    Joined: Dec 14, 2010
    Posts: 153

    Work In Progress
    Member

    With a 29" tire 3.9 or 3.7 should be fine. Even a 4.1 would be ok at 60...
     
    squirrel likes this.
  17. That clarifies things a little bit. Still keep in mind that you are still running basically the same suspension as a Model T. Yes smaller diameter tires and solid steel wheels that replaced the wooden spokes and four wheel brakes that are now hydraulic. But the same basic suspension that was on use thirty years prior. My 1929 Model A is capable of 65 MPH so said the factory but 40 MPH is more relevant and safety wise can still get you killed in an accident even with lap style seat belts. Stay safe and do not jeopardize your safety.
     
  18. squirrel
    Joined: Sep 23, 2004
    Posts: 46,425

    squirrel
    Member

    I checked the rear gear ratio on my Model T the easy way...jack up a rear wheel, put a piece of tape on it, turn the crank in high gear until the wheel turns two revolutions, and count how many times the engine crank went around. 3.6 it was

    I don't expect you have a crank for yours?
     
  19. Well no, but that is a good idea .I can fabricate on or just put a big socket on it. Thanks
     
  20. Used 1-5/16 socket turned engine, got roughly 3-3/4 turns to 2 turns on wheel , so looks like 3.78.
     
    squirrel likes this.
  21. You can do the same just turning the wheel in neutral and count the turns of driveshaft. Guess that don't work on a torque tube though. LOL

    If there was two of you you could pull the plugs and turn the motor by have or of you have a crank nut you could use a beaker bar. I got an idea that after 45 years the OP has that figured out.

    Where the problem lies on our early rear ends is that gears are not as available as on our late model rears. If my car was not a real pig of a car (3500lbs + ) and I had it I would install a 3.2-3.5 gear and be happy with it.
     
  22. Well, going with a 3.25 , hopefully wont need a push at a red light. Got all parts yesterday ( after Fraudex delivered to wrong address) I have been getting parts out of Piedmont SC and they are quick. Waiting for the driveshaft bearing I ordered from Skip Haney. Anyway , have never done a banjo, but did get 5 or so of pages with all sorts of pics instructions and tolerances so either I will be on here bragging in a few days or when ever I get to it or I will be posting a wanted add for a banjo.
     
    porknbeaner, 427 sleeper and warbird1 like this.

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