Speedometer is driving me crazy- Something is Wrong

1WildRT said

Haven't read everyone's posts... So I might be repeating stuff.. Here goes..

First how is the odometer vs travelled distance... The odometer doesn't need the speedometer to be calibrated.... If the odometer is off your speedometer gear is wrong.... If the Odometer is accurate and the speedo is off the speedo needs to be calibrated...

The speedometer should read 60 MPH when the cable is spinning 1000 rpm

Click to expand...

So I did some testing today and it doesn’t seem like the speedometer is wrong.
Using a Photo Cell RPM meter and an old sears 1000rpm drill that actually runs at 1060 rpm (+10%) tested with the rpm meter.
I disconnected the Speedo cable from the transmission and hooked into the drill and ran it at full rpm (1060) for 2 minutes on a stopwatch with my buddy watching the speedometer and odometer. The result was a steady 67-68mph and a total of 2.2 miles.
Now I am wondering about the gear inside the transmission.