• Hello K code experts. I have a question that hopefully someone can answer. In reviewing Tony Gregory’s 4th edition, I noted that early k codes were built with predominantly 3.89 gear ratio code 8 with code 5 3.50 being non existent until much later. Then around Oct 1 64, there was an obvious switch to code 5 being the predominant over code 8. Code 9 is rare in both cases but even more rare as production progressed. Does anyone know why? Were too many K codes blowing up? Did this correspond with a level change? I’d be interested to hear what you guys think.

    Thanks

    Bartman.

    Barry

    1965 K code coupe (Aug. 13/64)-restored
    1939 International D2 1/2 ton PU-restored

    1963 Impala SS 409 coupe-original
    1947 Whizzer motorcycle-restored
    2012 Harley Davidson FLHP

    Edited once, last by Bartman2 (April 26, 2020 at 4:03 AM).

  • Early k-codes ran a sports type bw t-10 4 speed close ratio transmission with a 2.32 first gear, with the 3.89 rear gears this was rather steep gears , i believe they switched to the toploader 4 speed afterwards with a slight different gearset but still a close ratio gearbox and backed it with 3.50 rear gears and left the 3.89 as a customer option. If i remember correctly.

  • Interesting, thanks Zeke!

    Barry

    1965 K code coupe (Aug. 13/64)-restored
    1939 International D2 1/2 ton PU-restored

    1963 Impala SS 409 coupe-original
    1947 Whizzer motorcycle-restored
    2012 Harley Davidson FLHP

    • Official Post

    Early k-codes ran a sports type bw t-10 4 speed close ratio transmission with a 2.32 first gear, with the 3.89 rear gears this was rather steep gears , i believe they switched to the toploader 4 speed afterwards with a slight different gearset but still a close ratio gearbox and backed it with 3.50 rear gears and left the 3.89 as a customer option. If i remember correctly.

    Are you referring to K code Mustangs or early Fairlanes regarding the T10 transmission?

    -Fred-

    65 Koupe early San Jose Phoenician Yellow 4 speed
    66 GT Koupe Dearborn Blue 4 speed
    66 KGT San Jose fastback pony interior Silver Frost 4 speed
    64 Falcon sedan delivery 289 4 speed
    65 Ranchero 289 4 speed
    66 Corvette roadster 427/425 4 speed

  • the top loader was not developed with the stronger 28 spline yoke shaft until late 64or early 65 and ford devolped the stronger top loader because they found the bw t-10 to have problems with popping out of gear and also grinding when shifting under hard acceleration.

  • Early 65 shelbys ran an aluminum case BW t-10 4speed with dtl 3.89 gears as standard . Later this fell also to an optional rearend gear, and the t-10 also was dropped completely in favor of the toploader 28 spline cr trans.

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