Speedo cable problem

J Witt

J Witt

Well-known member
The cable keeps backing out of the speedometer. I have the oval speedo with the small cable, about 1/8 square on the end. It acts to me like the cable is a little bit short.

It will run ok for a few miles then stop working. The drive gear is still engaged as the cable is still turning, but the head unit stops running. The speedo itself appears to work OK as I can drive it with an electric screwdriver and all is well.

Ideas anyone?

Thanks,

John
 
Is this a problem that just started, or after installing a new speedo? Did you do any work to the car before this showed up? Are you a new owner of this car and inherited this issue with the car?
Bob
 
New owner. Speedo cable wasn't connected and so wasn't working when I got the car. I assembled everything and the operation was good for about 75 miles or so.

And I did lots of work on the car!!
 
When I bought my replacement cable a few months ago it came with a small pin. This is to insert into the housing hole at the back of the trans to prevent the cable going in too deep.
 
This cable has some sort of shoulder inside the trans end of the cable housing that prevents it from heading south. That is, if you tug on the transmission end of the cable it will not pull out. My first thought was that the cable was creeping down, but that's not the case.
 
I think the little brass shoulder goes to the top or speedo end of the cable. And I can second what Full Race said about the pin in the drive unit. If I didn't have it in, the square end would slip past the square female section of the drive and stop turning the cable.
 
After taking it all apart again, it appears the issue may be a late cable on an early speedo head, with the smaller end just spinning inside the input shaft of the speedometer.

I'm going to do some more parts juggling to get a full set of the matching parts.

Thanks for the great tips,

John
 
So got the matching set of speedo, cable and drive gear and everything now works. The cable is the 28-29 style whereas before I had the 30-31 cable on the oval speedo -- not workee, my bad.

The shaft was replaced in the drive gear with a round-with-ear style from Snyder's and it did require the dowel spacer to put the Vintique cable in the right position.

Thanks for all the advice,

John
 
I'm having an issue where my mph starts correct and then does not keep up (checked with GPS app on phone). My cable looks a little stretched out where I pulled it out to get the speedo removed originally before being fixed. The odometer was stuck and now they are both reading incorrectly.

When twisting the square rod in he cable, it seems to get stuck after a few spins. When I pull it out a good amount this seems to go away. Also, there looks to be a few washers between the square rod and the speedo attachment.

Does anyone have any suggestions or things I should test? I'm new to Model A repair still and am pretty green with cars in general.
 
If the input is too tight to spin easily with the tips of your fingers, then it is too tight and needs servicing. If it is an oval faced speedo, the end of the cable that goes into the head is .124 square where as the one for the round faced speedo is .104 square. If it wrong the cable will slip inside the drive input and read erratically and show a slower speed.
 
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