Early Speedometer rebuilt and working then stopped. Cable?
 

I just got my speedometer back from Speedometers.com and they did a great job. Well at least it was working for about 25 miles according to my newly working odometer and then stopped. Could it be the speedometer cable? Why would that go bad all of a sudden is what I am thinking. Any thoughts? This is on a 66.

So do cables just break? Fishy that it happened so close to when my new speedometer as installed. Any ideas? Any else have a cable go?

Speedocable?

Did the speedo just stop dead, as in no movement at all? If so, the speedo cable could have fallen off. Easy enough to check - I'm assuming you know how as you've already pulled the speedo out to send it in for repairs, right? Or it could've fallen off the transmission. See this thread on how to find that end:
http://forums.pelicanparts.com/porsche-911-technical-forum/280377-speedo-cable-tranny-end.html?highlight=speedo

If it's still attached at both ends, I'd be looking at the warranty on the work from the speedo repair. I guess the proof of mileage is pretty easy! :D

edit: I don't have a definitive answer as to whether or not speedo cables break, but I can't say I've ever heard of it. They're pretty rugged, and except for the transmission mount, the cable is all inside, so not exposed to road grime, water, etc.

Pull the speedo, drive the car and look to see if the cable is turning. If not, you will need a new one. And yes... They do break. Replacement is a pain since you must fish it through the tunnel. Lots of stuff must come out for access.