The Ford Barn

1930 coupe · 11-06-2020, 07:23 PM

I have a box full of spare speedometers that I have been working on.
I have got most of them working and calibrated, I have built tools to calibrate them on the bench using cable rpm's versus MPH it is adjustable and I can check all speeds for accuracy. I have one speedometer that reads 2 or 3 MPH low at 15 and 20 MPH and 2 or 3 MPH high at 60 MPH. It is pretty close at 40 and 45 MPH. I have been playing with the magnet and spring but cannot get it
accurate at all speeds. I believe that it is a spring issue, I have loosened and tightened the spring slightly without any improvement, do I need to make larger adjustments on the spring or does the spring need replacement.
Do not tell me to send it to someone, I enjoy learning and doing all my own work, and these are spare speedometers.

11-06-2020, 07:23 PM	#1
1930 coupe Senior Member Join Date: May 2010 Posts: 226	Speedometer Calibration I have a box full of spare speedometers that I have been working on. I have got most of them working and calibrated, I have built tools to calibrate them on the bench using cable rpm's versus MPH it is adjustable and I can check all speeds for accuracy. I have one speedometer that reads 2 or 3 MPH low at 15 and 20 MPH and 2 or 3 MPH high at 60 MPH. It is pretty close at 40 and 45 MPH. I have been playing with the magnet and spring but cannot get it accurate at all speeds. I believe that it is a spring issue, I have loosened and tightened the spring slightly without any improvement, do I need to make larger adjustments on the spring or does the spring need replacement. Do not tell me to send it to someone, I enjoy learning and doing all my own work, and these are spare speedometers.