‘36 Airstream Calibration of speedometer using my lathe

[Piaras]

The speedo was slightly slow based upon the reading from the gps unit. Research shows that 60 mph equals 1000 rpm on the drive cable.

Disassembled the speedometer via removing the trim bezel and glass. Removed the needle by carefully pulling up off the pin and the face plate was set aside. Reinstalled the indicator. And placed a mark on the edge of the speedo marking 60 mph.
 

Inside the unit there is a small loop indicated in the photo with the yellow line. That is the adjuster. I made a mark with a marker of the original position of the center of the hole, blue line. 
 

I set up my lathe to 1000 rpm and installed my collet chuck with a #2 Robertson square drive. In reverse, clockwise when looking at the spindle.

 

Carefully placed the speedo onto the driver in the cable socket and started the lathe. I have a VFD on the motor so it is not a fast start. Takes about 5 seconds to get to speed. The indicator was slow. Stop and now I moved the adjuster (yellow line points to the loop) and moved it clockwise by a small amount and retested. Took a couple moves to be satisfied.
 

The final position is shown by the new mark, red line in photo. The loop is centered on the new mark.
 

Reinstall all the removed parts and reinstall in the dash.

 

Edited April 9, 2023 by Piaras (see edit history)

[Uptowndodge]

Are your other gauges in good shape, I have some 36 Desoto Airstream Nos gauges 

[Piaras]

Yes all my gauges are good, and have spares to boot.

Pierre