Re: Peterson's 1940 Packard

Posted by BH On 2011/9/22 9:33:27

The odometer is driven directly by the speedometer cable (through gears).

The needle of the speedometer is driven indirectly by a rotating magnetic field created by a permanent magnet that's driven off same cable.

Tweaking the speedo calibration is not the proper solution for incorrect drive/driven gears at the transmission or changing tire size or axle ratio, etc.

When an appropriate ratio couldn't be achieved by swapping out the drive/driven gears for the transmission, there used be inline adapters that could be installed at the trans end of the cable, but they didn't come cheap - even back then.