Testing speedometers with a drill

[Patrick B.]

Does anyone know the cable rpm to speed ratio for C2 speedometers and the direction of rotation?

[Duke W.]

Re: Testing speedometers with a drill

I believe the GM spec for speedos of the era is 1000 cable revs = 60 MPH, and you can linearly proportion from there.

Duke

[Ralph E.]

Re: Testing speedometers with a drill

Which direction, CW or CCW

[Mike E.]

Re: Testing speedometers with a drill

Counterclockwise.

[Ralph E.]

Re: Testing speedometers with a drill

Thanks for the info

[Patrick B.]

Re: Testing speedometers with a drill

Duke ---- You are absolutely correct. By pure luck my drill ran about 2000 rpm wide open. I tested 5 tachs that all read about 4000 rpm ( twice cable speed) and 3 speedometers that all read about 120 mph.