Technical model A speedo issues

I have a 29 model A with the stock speedo. I'm having issues getting the speedo to work. I've disconnected the speedo cable from the speedo and watched the cable as I drive and it spins. I've take the speedo cable and disconnected it from the trans and spun the speedo cable with a drill and the speedo works. But they don't work together. Any ideas ?

 

my guess would be that the inner cable is too short and can not engage both the speedometer and the drive on the transmission at the same time

 

bad speedo gear on the driveline?

 

I think the center piece on the speedo cable is square. Maybe the piece that receives the cable on the driveline or the inner cable on that end is rounded/stripped and it isn't spinning with the driveline? If the speedo works with a drill it should be the driveline side.

You can get a new speedo cable from Mac's. I think I have a brand new one on the shelf somewhere. I bought a few extra parts that I didn't end up using on my build and I think the speedo cable is one of them.

 

Could be an engagement issue, something a bit short and you get it in further when disconnected...
You should have a very fat cable, and drive by round end with a key...'30 up uses modernish thin cable with small square drive.

 

I had this very thing last weekend! Speedo had been working fine then when a "lets see how fast my car will go" run was over I heard a strange noise from under the floor - and the speedo was no longer reading.
I immediately suspected the usual faults - cable (ok); drive (ok) so I pulled the speedo itself out onto the work bench to try - it worked ok too!

Turned out the second-hand drive unit had a fair amount (but not all) of the female drive square worn out. Right amount as to where the cable square finished when installed. It initially worked only because of where the inner cable had ended up when installed - until the speed run that is!
Luckily I had a second "21" drive that I put in - fixed just like that.

So worth checking how much of the female square in the drive is actually any good before pulling too much apart.

 

By the way...Bratton's Model A parts has all the drive bits.

 

Snyders is better

 

thanks for the info

 

But Bert's beats them both!!