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Old 11-07-2020, 06:50 PM   #7
1930 coupe
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Join Date: May 2010
Posts: 226
Default Re: Speedometer Calibration

Quote:
Originally Posted by AL in NY View Post
I have posted this adjustment on VFF and it comes directly from Leonard Nickols who rebuilds and sells Model A speedometers. This is an adjust to correct the speed error on the round Stewart Warner speedometer. When rebuilders rebuild speedometers they mostly check to see that the mileage(odometer) reads correctly, not the speed.........

Remove the speedometer from the dashboard. Now carefully remove the cover on the back of the speedometer. You will see a very small hair spring on the top of the rotating speed wheel which has an small screw at it's center. Now move the speed wheel to show the speed you were reading while driving (50MPH) and note the position of the hair spring adjusting screw (let's say the slot runs 4 to10 o'clock). Now move the speed wheel to the corrected MPH you want the speedo to read (46-GPS). Look at the hair spring adjusting screw and adjust it to the position you saw for the 50 MPH reading. Your speedo should now be calibrated.
That is true for a lot of speedometers but some of them are reading low at slow speeds and high at fast speeds, or they are not liner. That is what I am trying to learn how to correct.
If they are reading high or low at all speeds, that is easy to correct.
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