Technical '55 Ford CV speedo problem

Working on a '55 Crown Victoria.
The owner passed away a year or so ago, and the car was sitting. The son wants the car gone over to make it safe and drivable. Wiring nightmare.
The problem is the speedometer. It was not working when I got the car. The odometer did work.
I disassembled, cleaned, lubed (3 in 1 oil, lightly applied), and reassembled.
A test drive showed the speedo and odometer working and apparently accurate.
Wasn't able to test drive again due to big snows for about a month.
Took it out again and speedo is not working again! Odometer does work.
Took the unit out and checked for any mechanical interference, saw none. If I spin the unit with a square bit and a drill, it will move the needle smoothly.
The speedometer cable spins freely when you drive the car without the unit installed.
The cable seems fine, the unit seems fine, but when you assemble them, the speedo will not work.
The cable is fully installed, and it is turning, as the odometer works.
From what I understand, there is a magnet set up in the speedometer head that drives the needle. Why would it work on the drill (not at a real high speed), but not even budge when being driven by the cable?
I have checked to see that the needle is free to move.
Any ideas?
Why would it work, and then stop working again?
I'd really appreciate any input.
Thanks,
GB

 

is the inner part of the cable, longer than the outer part? ie, is the cable pushing on the moving part of the speedometer mechanism, when you tight up the nut?

 

I just checked that. The cable was sticking out past the bell at the end of the sheath about a half inch, maybe a little less. I pushed the cable in as far as it would go, and it is now at about a quarter of an inch.
Unfortunately there is a dead '56 Cadillac behind it right now, so I had to jack it up and try it. The needle is now moving, but it seems that it isn't accurate. Hard to judge with the rear on jack stands, but it seems like the speed isn't accurate.
But I think that you are on to something!

If the needle is pressing too hard on the 'barrel' type mechanism, that could be it.
Thanks a lot.
I'm going to take the cable loose at the trans end and pull the cable toward the trans a little bit if I can.
Many, many thanks!

 

I caused that on mine by tightening the speedo/odometer mechanism too tightly into the housing.
The very slight twist on the frame would make it bind, the needle would wobble at low speed etc.
Backed the mounting nuts off a fraction and that solved it (mounted in rubber bungs).

Phil

 

I would talk to Rusty and tell him what it is and is not doing, He has repaired one for me and I purchased a NOS SW 1954 speedometer from him. HRP

https://www.speedoservice.com/

 

X2 on Rusty. He must have cornered the market on '54 Ford speedometers. He sold one to me a couple of months ago. Shipped it to me before asking for payment. Real stand up guy.

 

Bought a new cable from him, plastic covered and lined for my 56 Ford. Works unbelievably smooth thru a gear transmission for accuracy. Told me where to buy that too. Great service..

 

The OP sent the 55 Ford speedometer in and I got it checked out. The speed was not working due to loss of magnetism (we all have that problem when we get older).

I tore it down and checked the magnet with a gauss meter before recharging it on the magneto magnet charger.

Cleaned everything up and checked tolerances, lubricated everything up and reassembled the speedometer with a NOS odometer.
Then demagnetized the magnet while the speedometer runs on the test bench to calibrate.
Made up a new speedometer cable and housing and now it’s headed back to Greg.
The lens is and old one I use for calibration, that’s why it’s all scratched up.
I use a calibration computer to backup the old Stewart Warner 890 test bench in the background for fine tuning calibration.
Thanks to all of you for the recommendation of my services.



Sent from my iPhone
www.speedoservice.com
Should I rush your rush job or the rush job I was rushing when you rushed in?

Elwood: There's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark out, and we're wearing sunglasses.
Joliet Jake: Hit it!

 

I received the rebuilt unit from Rusty at Speedometer Service. Very nice job.
Installed the unit and new cable supplied by him into the car, and it works as smooth as silk.
Very happy with the work, the turnaround time, and it was done at what I would consider a very reasonable price.
Would certainly recommend Rusty at SpeedoService!
Thanks to everyone for the help.
Greg