'62 speedometer doesn't work

[uglydukwling]

The speedometer in my 62 stopped working without warning (no noise, no jumping needle) as I was driving the car. Since "it's always the cable", I pulled the cable core out of my parts car before starting to work on the good car. When I got the cable core out of the good one, I couldn't see anything wrong with it, but I installed the replacement anyway. Doesn't work. I tried installing the speedometer out of the parts car. Still doesn't work.

Driving the car without the speedometer installed, I can see the cable core turning. When I spin the input to the speedometer by hand, the needle moves and the odometer advances. Put everything together and it doesn't work.

I've heard the theory that the core may not be sticking out of the cable housing far enough to engage with the speedometer input, but I can't see how that happens. The core has a collar that's supposed to prevent it from going too far into the housing. That should ensure that it sticks out the proper amount, so it should engage the speedometer. Does anyone know how far the cable core should protrude from its housing, and is there any way to make sure it's engaging? Due to the tight clearance, it's impossible to see what's going on behind the speedometer when I try to connect the cable.

Incidentally, the cables from both cars, both without cruise control, measure 46" long, quite a difference from the 83" Rock Auto says they should be.

[frasern]

It sounds to me like the plastic driven gear has worn down, it should be cylindrical. If it's coke bottle shaped, the teeth are skipping when under load.
I can't believe Rock auto got something wrong!

[uglydukwling]

OK, it sounds like the next step is to examine the driven gear. Unfortunately, Ford was considerate enough to put the cable connection to the transmission on top of the transmission cross-member. It looks like the cross-member has to be removed to get at the gear. Has anyone found an easier way to do it? If it is the gear that's at fault, are replacements available?

I don't really want to get into this job and then find out after all the trouble, that the problem was elsewhere.
Are there any simpler possibilities that I should investigate first?

[frasern]

To be honest, I have never removed it from my '62, however, I don't recall it's being that hard to reach. Before buying a Chinese replacement, I would check out the one in your parts car. There may be a number of variants, so count the number of teeth before ordering anything new.
I think you have already tried all the simpler possibilities. If the head and cable are okay, it has to be the drive or driven gear, not sure what the drive gear looks like in a PCA, but usually they are steel, and driven gears are plastic.

You said you can see the cable turning when you drive, perhaps try lightly holding it with some pliers and see if you can feel it skipping.

[Lee]

You can reach the speedometer gear without removing the crossmember. It’s easier if you can do it standing up, but not impossible. As I recall, you’ll just need a 1/4 or 5/16” socket, and a few slight contortions.

[uglydukwling]

I'll have to wait until I get my hoist working again before I can try to get the gear out. The parts car is buried in the back of my barn and there's no way I can get it to the hoist. It might actually be easier to get the gear out of it, though. It's far enough gone that I don't mind cutting a hole in the floor. I'll post what I find once I get back to the project.

[Solid]

If the cable is turning then I’d triple check it is fully inserted into the speedo. I had this behavior as well at one point and kept thinking it was fully seated, then discovered that it really wasn’t.