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Thread: speedo gear ratios

  1. #1
    Speedster Member
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    Question speedo gear ratios

    Have 62 GT Hawk Speedo reads about 10% fast (eg 65 MPH shown on GPS when 75 MPH shows on mechanical speedo) It now has a 19 tooth pinion installed. Need to adjust pinion to bring it into correct speed indication. DOES ANYONE HAVE THE CHART FROM THE PARTS MANUAL THAT SHOWS GEAR COMBOS FOR THIS CAR? It has the 3:31 rear gear. Thanks

  2. #2
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    Are you running 6.70 x 15 bias plys ? If not, you need to convert diameters in addition to pinion changes (if neccesary)

  3. #3
    Golden Hawk Member StudeRich's Avatar
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    Yes the 1544761 19 tooth Pinion IS correct for Std., O.D., or Auto Trans. if you have the 8 Tooth Drive Gear 1546046 in the Trans. and the actual Ring & Pinion in the Diff. is correct, the only issue other than a worn Speedometer is the Tire Diameter is wrong; not the same as a 6.70X15 Bias Ply.

    But keep in mind that all Studebakers, especially Hawks, did read Faster than actual in drive tests of New Cars, and they have not improved over time.

    The 1544763 is a 21 Tooth Pinion, maybe that would slow it down enough, 2 numbers higher.

    The complete Shop Manual, Chassis and Body Parts Catalog CD is only $25.00, I just can't imagine owning a Studebaker without these for MANY purposes.
    Last edited by StudeRich; 10-29-2018 at 03:42 PM.
    StudeRich
    Second Generation Stude Driver,
    Proud '54 Starliner Owner




  4. #4
    President Member TWChamp's Avatar
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    Also, I'd check the odometer and make sure that is correct before doing anything to the speedometer.
    I just installed 225-75-15 radial tires on my 1950, but they are still a hair smaller than the 7.60-15 bias tires.
    I now wish I'd have bought 235-75-15, even though the 225 is supposed to be the correct radial size.

  5. #5
    President Member bensherb's Avatar
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    If it reads high by 10% simply incerase the size of the driven gear by 10%. As Rich pointed out, if the current gear is 19 teeth and the speedo reads 10% high you need a 20.9 tooth gear. A 21 tooth gear should do quite well.

    There is no need to worry about the axle gearing or tire size if you have already determined the percent of disparity between the indicated speed and the actual speed.
    Last edited by bensherb; 10-29-2018 at 08:52 PM.

  6. #6
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    Thanks for all responses. Can always count on this forum. BTW the rear tires are 205/75 R15, should be very nearly the same as the OEM 670-15. Now know I need a 21 tooth pinion gear. Anyone have one for sale?

    Thanks again.

    Ken Michael

  7. #7
    Golden Hawk Member StudeRich's Avatar
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    Quote Originally Posted by Kenmike2 View Post
    Thanks for all responses. Can always count on this forum. BTW the rear tires are 205/75 R15, should be very nearly the same as the OEM 670-15. Now know I need a 21 tooth pinion gear. Anyone have one for sale?Thanks again.Ken Michael
    Studebaker Vendors have 1544763 listed:

    http://studebakervendors.com

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