‘46 pickup speedometer—notes & question
 

Since my speedometer needle was sticking against the back plate at about “40 mph,”, I decided to remove just the odometer unit, rather than taking out the entire gauge array behind the glass. A whole lot of contorted reaching under the dash led me to take out 5 threaded screws and turning off the speedo cable holder and retracting the drive inner cable. Also pried out the two light bulbs.
— the unit, a Stewart Warner 679x/ P1 by its label, was not visibly defective, but I disassembled it down to the gears. Lubricated with clock oil and a little grease to the pinion.
—the squared off inner cable needed to be filed in order to seat it firmly back in the square receiver. The knurled keeper would otherwise not reach the threaded end of the odometer shaft
—the needle itself may have been soldered on. It fell off when I straightened the indicator needle. Glued it back with gel super glue and then when dry, a dash of Duco cement.
—I could not easily have replaced the screws in that cramped space without the aid of a clever holding tool made by Ullman devices
https://ullmandevices.com/collections/specialty-tools
After all was re-fitted, I checked the transmission end of the cable and made sure it felt seated, though I could not see that. I also squirted some Aero Kroil down the cable from the dash side, hoping gravity and this oil’s excellent penetration would do some good. The inner cable seemed to turn by finger pressure without binding.
The repair fixed the sticking needle. Yet, the needle bounces around when accelerating. It jiggles in 10 -15 mph increments.
Can anyone tell me what might cause that jumping? The obvious culprit is the cable itself, whether binding against the outer cable or slipping in the square hole. I’ve never seen a working ‘46 speedometer and so I’m ignorant about what is normal.

Re: ‘46 pickup speedometer—notes & question
 

I can't speak to the pickup version, but the speedo in my 46 Tudor has an steady sweep as does my 49 F1. Your thought on a cable issue would seem correct.

Re: ‘46 pickup speedometer—notes & question
 

If the cable and sheath are in good condition with no kinks, and are sufficient lubricated, it is likely an internal wear problem. At our shop we send them to Bob's Speedometer, They will inspect the unit and give you an estimate of repair costs. 1-800-592-9673.

Re: ‘46 pickup speedometer—notes & question
 

Before removing the speedometer for repair, might try lubing the cable again with something more substantial. Aero Kroil isn't much of a lubricant in my experience.
Good luck!

Re: ‘46 pickup speedometer—notes & question
 

The speedometer in my’46 Coupe was “surging” at lower speeds. What I found was the cable wasn’t routed square into the back of the speedometer. Rerouted and the problem went away.

Re: ‘46 pickup speedometer—notes & question
 

You must have a 'tonner' pickup with a 60 mph speedometer and the quadrants showing when to shift. Or... your speedometer came from a bigger truck if yours is a half ton. Or... I could be wrong. I have fought the bounce for years, having both types of trucks. You have an 8' bed and 17" multipiece wheels?

Re: ‘46 pickup speedometer—notes & question
 

My ‘46 half ton was equipped with a four speed transmission, conventional 16” wheels

Re: ‘46 pickup speedometer—notes & question
 

Like I said, I could be wrong. Somebody here will know. Perhaps the 60 mph speedo was because you have the 'big truck' 4 speed trans. As far as the bouncing needle, I'm watching your thread for info!

Re: ‘46 pickup speedometer—notes & question
 

Thanks for the tips, guys. I removed the 53” cable and squirted it with Deep Creep, some graphite lubricant for locks, and then 3 in 1 oil. The inner shaft spun freely but alas the needle bounced as much as ever. I’m used to estimating speed, anyway. Might try Bob’s Speedometer to see if the hair spring or magnet are the problem.

Re: ‘46 pickup speedometer—notes & question
 

I had my son put the speedometer app on my phone.