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Rear End Gear Ratio for Mileage

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  • Rear End Gear Ratio for Mileage

    I think I about have all the parts together to convert my '63 Champ pickup to a GM 700R4 automatic overdrive. I hope to be able to post pictures on this media as we progress.

    My question today is what would be the best rear-end gear ratio for the optimum in fuel mileage. Presently I have a twin traction 4.09 rearend on the truck. I won't be hauling anything "super heavy", like a truck load of bricks or lead pipe! So I don't need to worry about that... and of course this conversion would be after I try the truck with the 4.09 and overdrive. I know if I go with too low (numerically) a gear ratio it will be as bad as too high.

    Any suggestions?

    Laisez le bon temps roulez avec un Studebaker

  • #2
    I would suggest trying it out with the 4.09 and going from there, you
    are going to end up with an impressive pulling grunt. The 700 has a
    3:1 first gear, which will be nice for towing and take off. The OD is
    a .8:1. Once you have it together and calculate your mileage, you can
    figure out what to do then.


    1963 Studebaker Avanti, 102,000, custom made brake brackets to mount 1998 Mustang GT 4 wheel disc brakes (soon to get 13" Cobra front brakes, 2003 Mustang Cobra 17" wheels, GM altenator, will be getting : 97 Camaro Z28 tan leather seats, 97 Camaro Z28 T-56 6-speed trans, Ported 'R3' style Avanti heads with stainless full flow valves, 'R3' 276 duration cam w/chrysler solid lifters, shortened push rods, aluminum cam gear, Edelbrock AFB Carb, GM HEI distributor, 8.8mm plug wires, waiting in the garage.
    '63 Avanti R1, '03 Mustang Cobra 13" front disc/98 GT rear brakes, 03 Cobra 17" wheels, GM alt, 97 Z28 leather seats, TKO 5-spd, Ported heads w/SST full flow valves.
    Check out my disc brake adapters to install 1994-2004 Mustang disc brakes on your Studebaker!!
    I have also written many TECH how to articles, do a search for my Forum name to find them