Mk3 Speedometer stopped indicating

Mk3 speedo has been in service for 17,000+ miles.
I bought bike with 8000 indicated, installed a new drive as OEM had failed, tiny rivets failed holding big gear.
Today pulled speedo , cable, and drive and nothing appears failed.
Jack up rear, turn wheel , cable turns and removed the cable looks fine.
Drive looks fine.
Put a square drive in drill to turn speedo and the speedo gives a steady reading.

I cant relate drill speed to actual speed. Is there a chart to help relate these speeds?

p400 said:

I cant relate drill speed to actual speed. Is there a chart to help relate these speeds?

Click to expand...

The ratio is 1000 (cable turns per mile printed at the bottom of the dial) so a drill speed of 1000 RPM should give a reading of 60 MPH (or 6 MPH per 100 RPM).

I've been struggling two seasons with erratic speedo needle. Fit a new emgo drive but didn't solve. Cleaned/greased cable no change. Checked speedo with drill on the drive end of cable, worked somewhat but found it was very sensitive how much inner cable was pushed into outer sleeve. Later found the metal crimped fitting at speedo end had slipped forward along the plastic sleeve somewhat, which changed how much cable end engages into speedo. A new cable cured this.

Thank you, this slipped crimped fitting on the inner cable might be the issue.
This speedo just kept indicating slower and slower, then zero.

Replaced the cable first, no fix.
replaced the rear drive, all is well.
New parts from Andover, excellent.