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Technical Freeway flyer traditional flatty drivetrain?

Discussion in 'The Hokey Ass Message Board' started by alteredpilot, Jan 9, 2016.

  1. I'm sure this has been covered but I couldn't figger out the search criteria.

    I have a Model A chassis and a 23 roadster body and all the stuff for a '62 era drivetrain. I'd really like a car that can run at fwy speeds without any headaches, but I've had an itch to build a post war hot rod. Can you have both?

    If so, what trans/rear end combo gets you there? Can you get there with a banger or or is this strictly v8 territory?

    Any input is greatly appreciated, even if it's a link to an existing thread.

    Thanks.
     
  2. Model A Gomez
    Joined: Aug 26, 2006
    Posts: 1,188

    Model A Gomez
    Member

    Running a Ford banjo rear end with a 28' tall tire and a stock 3:78 gear will put you at 2720 rpm at 60mph and a 3:54 will put you at 2550 rpm. This is winding a banger fairly tight especially if it is still a Babbitt motor . I have a counter balanced and inserted H&H banger with a lightened flywheel and a 3:78 gear and 7:00 16s and about 55 is where it seems comfortable. Long stroke with a large bore designed for torque at low rpms.
     
  3. Post war or pre war? Post war is easy enough, freeway speeds haven't changed in my lifetime other then when we had to try and drive 55.

    We traveled all over the western 4 in a '53 merc in the summer of '69. The speed limit in good old sunny California was 70 but Nevada and Oregon had open speed law.

    Merc flathead stock bore and stroke, offy heads and a 2x2 intake, a mallory dual point. Stock camshaft and the only port work was a divider in the center exhaust. 3 speed OD.

    We replaced a belt and points and plugs once. it would cruise @ 70 no problem and we did have it up to 100 ( on the speedo) a couple of times in Nevada and Oregon.

    With a banger I would think that it would be work to build one that would cruise @ 70 but I don't doubt that it can be done. Check the banger thread for info on that subject they have a monthly thread. Here is the current offering:

    http://www.jalopyjournal.com/forum/...banger-meet-new-year-and-old-bangers.1003733/
     
  4. gnichols
    Joined: Mar 6, 2008
    Posts: 10,649

    gnichols
    Member
    from Tampa, FL

    Why not look at some new cars, to see what tranny ratios, final drive numbers, and tire sizes they run for comparison? Or take a look back? When I was stationed in Germany 1968-70, I was amazed that the small displacement European coupes and sedans with, say, 2000cc engines (big at the time for them but still about the same size as a V8-60) could easily cruise at 100 mph all day long. Of course they had more power (which you can get if you want with a bucket of cash) and they probably ran at higher RPMs, but looking at the specs on their drive trains might be a good place to start your research. Even smaller... my little 1300cc Alfa coupe, with 105 barking HP would also cruise at 100 all day, with it's 5spd OD, dual Webers, and dinky tires on 13" rims. So why not take a look back at something like a 1972 BMW 2002, for example? Dialing your "research" back for benchmark cruising of 75 - 80 mph in the US should make it easier on the flatty and you will at least be able to keep up. Adding a small blower might be a good solution, IMHO, as you'll need the torque to help push all that air around your boxy old Ford (like mine!). Gary
     
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  5. petew
    Joined: Jul 21, 2010
    Posts: 204

    petew
    Member
    from Mebane, NC

    My banger has a 3.54 Model A rear and a T-5 transmission with a .68 5th gear. It runs at about 2000 RPM's at 68 mph. It's an inserted motor with a counter balanced crank.
     
  6. 3:54's and a Columbia OD?
     
  7. Tim,
    Now you are getting deep into bean land. Given my options I will go 2 speed rear way before I ever even think about an OD tranny and the Colombia is tits in my book.

    Like a 9" Ford though they may use too much torque for a banger to utilize. Everything in there is big and heavy.
     
  8. Revised idea: Healthy flat motor and 3:54's plus a Columbia OD.
     
  9. Well I am not your everyday flathead guy as everyone knows, but I would run one and while I like the idea of a full house banger the V8 is the direction I would choose.

    I actually had a chance to get a v12 with some speed parts during the holiday season, if I had had two nickels to rub together I would have told the HAMBer who wrote me to pick it up. The Big Lincoln motor while not normally a race motor is a real motor.
     
  10. Glenn Thoreson
    Joined: Aug 13, 2010
    Posts: 78

    Glenn Thoreson
    Member
    from SW Wyoming

    I'm running a stock '53 Merc flathead in my '42, through a '39 vintage 3 speed top loader and 3.54 gears. Stock wheels and tires (6:00x16).
    It runs down the road easily at 65 MPH and have run 75 with no problems at all. Your frame and body combo would make a great '50s period car and with such light weight it would have all the power a reasonable person could use.Hydraulic brakes are a must. I'm starting on an AV8 now with an 8BA flathead and the same transmission. A '40's rear axle will be my choice. Even with the 3.78 ratio it will be fine. Mind you, mine are driver cars, not street racers.These flatheads are tough and dependable if you use a good one. Good luck.
    Glenn
     
  11. haychrishay
    Joined: Jul 23, 2008
    Posts: 944

    haychrishay
    Member

    My Forty Ford has a Merc flatty with a stock stroke and a mild overbore. It has a stock 3 speed tranny and a Columbia two speed rear, I think it is a 3:78 ratio. When it had 750 16s on the rear it turned about 2200 at about 72-75 mph with one person in the car. It didn't have enough power to maintain that on long hills and especially if it was windy. This summer I put Offenhauser alluminum heads on it and changed to 235/16 radial tires . With two of us in the car it would run 70-72 at about 2400 rpm and it would power up the long hills with out losing speed. I just put an Offy two carb intake on it but haven't driven it much at highway speeds to see what difference the two carb intake makes. Let me clarify that these RPM's and speeds are with the Columbia engaged in overdrive. Hope that helps
     
  12. gnichols
    Joined: Mar 6, 2008
    Posts: 10,649

    gnichols
    Member
    from Tampa, FL

    ^ That's great! Just three questions. What is the OD ratio on the Columbia? And how tall is a 7.50 x 16? The 235/16? It's hard to calculate / appreciate the changes without being able to compare relative OA tire heights (by lazy amateurs on their computers) or diameters (racer math) to plug in the proper formulas. Gary
     
  13. haychrishay
    Joined: Jul 23, 2008
    Posts: 944

    haychrishay
    Member

     
  14. gnichols
    Joined: Mar 6, 2008
    Posts: 10,649

    gnichols
    Member
    from Tampa, FL

    ^ Thanx you Sir! Gary
     
  15. Gene Boul
    Joined: Feb 9, 2006
    Posts: 807

    Gene Boul

    My mild 46A IMG_0787 6.jpg IMG_0943.jpg B will run all day @ 65. We use 3.78 rear gears and a 235 X 15 X 75 tire. It has a 26 tooth 39 tranny...
     
  16. RainierHooker
    Joined: Dec 20, 2011
    Posts: 1,994

    RainierHooker
    Member
    from Tacoma, WA

    This thing gets driven every day (well, before I left to go overseas for a year) to work on the freeway. Mildly-built 286 flathead in front of an otherwise stock drivetrain...
    [​IMG]

    '39 transmission, 3.78:1 banjo. Likes 60-65, but'll do 75 before the 600-16 bias-ply tires start wandering too bad.
    [​IMG]

    ...and thats carting around a big fat sedan. Go for it.
     
  17. Shit my stock 40hp banger with 4.11 and 32.5 inch tall tires aka 7.50x17's will do 60. Thats all its really got. But it will so it. Throw a full house banger in there and maybe a little less rear gear and I bet it will maintain 60 easy
     

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