Classic/Antique Car Repair: Speedometer runs backwards

Question
Jack -

I have 30' Mocel A coupe with original Riley OHVC. Car was recently rebuilt with S-10 5-Speed transmission, Open drive shaft but original banjo rear end. The Stewart Warner speedometer registered "0 mph" while driving and the odometer rolled backwards. Cable is disconnected until I find what is causing the problem and I thought you might know. Speedo cable is connected to rear differential pickup not the S-10 transmission. Any ideas? Thanks for your help.
Jack -

Answer
Well, I don't know much about Model A's in that state, but if the thing is running in reverse, that can mean only one thing.  The cable is turning the wrong way.  Something needs to be reversed, or put on the other side of a gear, but somehow, you have to get the cable turning the right way.  I hope you find something that is reversible.  Maybe there is an adapter available that will reverse things.  Ask your suppliers of your new parts.  I bet this will not be a new problem to them.  Good luck.  jack