Testing a Mechanical Speedometer
 

Anyone have a foolproof way to test a mechanical speedo? I thought I remember something about using a electric drill and a flat bit. If so, what direction? I would like to test but I don't want to damage it by spinning it in the wrong direction. Thanks in advance.

Anyone done this?

Yes. Find a bit or make one to fit the square speedo drive. Use a variable speed drill and ramp up the speed slowly. Direction is the same as the direction the needle moves. Clockwise viewed from the front, ccw from the rear, so your drill should be running in reverse.

Hi Mike. Thanks for the help. My Dad gave me this speedo out of his old 74. He said it works but I wanted to double check before I put it up for sale. I'll get the drill out.
Thanks Again. J