The Ford Barn - View Single Post - '57 F-100 Gas Gauge

rotorwrench · 03-07-2018, 07:39 PM

Some sending units have the low resistance when the indicator reads full (full voltage to indicator). Others have high resistance when indicator reads full but the indicator will generally read full when you shut the electrical power off on those. It sounds like a mismatch on the rheostat function.

This link to Speedway lists common resistance values: https://www.speedwaymotors.com/the-t...ng-units/28745

I should also add that some indicator units have the internal works reversed in function from others. Most all of them use a heater coil on a bi-metallic strip to provide the movement of the indicator needle but the way it is attached to the needle can reverse the function.

03-07-2018, 07:39 PM	#12
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,426	Re: '57 F-100 Gas Gauge Some sending units have the low resistance when the indicator reads full (full voltage to indicator). Others have high resistance when indicator reads full but the indicator will generally read full when you shut the electrical power off on those. It sounds like a mismatch on the rheostat function. This link to Speedway lists common resistance values: https://www.speedwaymotors.com/the-t...ng-units/28745 I should also add that some indicator units have the internal works reversed in function from others. Most all of them use a heater coil on a bi-metallic strip to provide the movement of the indicator needle but the way it is attached to the needle can reverse the function. Last edited by rotorwrench; 03-07-2018 at 07:52 PM.