My son was doing some planning for the wheels, transmission and gearing for his totally awesome blown 1966 Malibu. He created a Microsoft Excel 97 spread sheet to figure out the impact of a six speed, wheels and gearing. I did some modifications to the spread sheet to present more information about the Pantera five speed gearing and tire size. To use the sheet down load by clicking on the link below and enter RPM and tire height. For those of you that are planning wheel size changes the calculator will help you analyze the impact of the wheels on your gearing and speed. The ratios that are loaded in the sheet are for the standard dash 2 ZF.
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Article published by Mike Dailey in Pantera International magazine about the gear calculator and the ZF six speed