Speedo testing.

Speedo newly rebuilt, new drive box, new cable. Still won't work. Testing components. Will try speedo head first. I know you can put an electric drill on the cable. If I remember correctly you spin the drill counter clockwise?

The needle rotates in a clockwise direction. You are driving it from the back of the gauge, so the direction of rotation is now counter clockwise. It's pretty obvious when you have it in your hands. I use a large common nail with a pyramid shaped point on it. Cut the head off and chuck it in your electric drill. With a small amount of pressure the point locks in the square drive recess.
The "connection" inside the gauge is magnetic, not strictly mechanical, so I don't think you can screw things up even if you got it wrong.

Thanks,
Well the speedo itself tests okay with drill so it is either the new cable or new drive box. When I insert the cable into the drive box I can't feel the inner cable lock into place and when I rotate the rear wheel forward the inner doesn't turn.

Attach the drill to the drive end of the cable...the inner square section holds well in the drill jaws....now confirm the speedo moves as expected (my batt powered drill makes it to around 50 Kph in its highest gear). Next I would check that the inner cable it correctly engaging with both the drive and the speedo. It is easy to have it too far into the drive such that the speedo end is not fully engaging the speedo receptacle. Also, confirm your inner cable isn't swapped end to end, meaning the end with the crimped on brass bush is correctly at the speedo end and not the drive end. The brass bush is what locates the speedo end in the outer sleeve correctly, limits its movement further into the sleeve.

I used the drive box end of the cable to spin the speedo and it spun up nicely. So it looks like the end that goes into the speedo which has the brass bush is correctly engaging. It would appear the problem is with the end that goes in the drive box.

Ensure the drive end is connected first, and that the inner cable is pushed into outer at speedo end such that brass bush is fully into the outer sleeving, otherwise the inner could be pushed toward speedo as you try to thread in the drive end and have no way to determine inner position if speedo already connected.

Also confirm drive is engaged on hug drive tangs and that cable can turn with enough wheel spins.

Failing those things, perhaps you have incorrect cable for your setup (there are a few different square section lengths for the different versions of speedos out there).

SPEEDOMETER GEARBOXES RIGHTHAND PRE MK3 RATIO 15:12​

PART NO​

060627​

RATIO 15:12 (1.25/1)

BORE FOR SPINDLE .674" (17.1MM)

WHEN FITTING NEW DRIVE CABLES ALWAYS CHECK CAREFULLY THAT THE INNER CABLE FULLY ENTERS THE INSTRUMENT WITHOUT ANY FORCE BEING REQUIRED. IT IS BEST TO FIT THE CABLE TO THE SPEEDOMETER GEARBOX OR TACHO DRIVE FIRST.

THE AMOUNT OF INNER CABLE AND PARTICULAR INSTRUMENT WILL ACCEPT IS SOMEWHAT VARIABLE BUT ANY CHRONO SHOULD ACCEPT AT LEAST 3/8" AND ANY MAGNETIC 1/2" MEASURING FROM THE END OF THE ALLOY FERRULE ON THE INNER CABLE.

ANY BURRS OR FRAYS CAUSING TIGHTNESS SHOULD BE REMOVED, AS WELL AS EXCESSIVE LENGTH. ALTHOUGH IF THE DRIVE COMPONENT WILL ACCEPT THE EXTRA LENGTH THE ALLOY FERRULE ON THE INNER CABLE CAN SOMETIMES BE MOVED ALONG SLIGHTLY.

TURNING TO A DIFFERENT PROBLEM, OCCASIONALLY A SPEEDOMETER GEARBOX CAN REFUSE TO ROTATE THE INNER CABLE DUE TO LACK OF CABLE ENGAGEMENT, WEAR ON THE CABLE OR A POORLY FORMED SQUARE IN THE GEARBOX OR ON THE CABLE. THIS CAN SOMETIMES BE RECTIFIED BY CLEANING THE INNER CABLE AND CAREFULLY WRAPPING WITH TIN FOIL.

PLEASE NOT THAT THESE COMMENTS/DIMENSIONS APPLY TO SMITHS EQUIPMENT AND MAY OR MAY NOT BE RELEVANT TO OTHER MANUFACTURERS.