Speedometer going whacko question

Speedometer in my '41 Pontiac is going all over the dial. Took it out, lubed it up and it worked ok until I hit the highway and now it's jumping around. Have what I thought was a trans leak from the bearing. Could the trans be leaking from the speedometer cable??

 

may have some debris binding inside near the magnetic wheel. I'd try a new quality cable first.

 

Usually caused from the cable binding in the housing. I usuall pull it out from the speedo end, wipe it down and re-install with powered graffite.

 

I agree with 1950ChevySuburuban. The magnetic wheel is sticking to the drum inside the speedometer. It's probably just dirty. Take the speedometer apart and clean it; it won't be as difficult as you might expect.

 

Frayed cable can bind and release causing jumping.

 

Lube the shaft.

 

I had this same problem. I lubed it and it still did it. Then I loosened up the speedo side a little and it works great! Must have been a little too long of drive cable, but this wasnt the original cable either.

 

if you dis***emble the drum you will HAVE to get the speedo re-calibraded.

 

Your 1941 Pontiac speedometer is very simple. And it will work much better after you take it apart and clean it. Recalibration afterwards would be nice, but it’s not really a precision instrument anyway; it probably won’t be any less accurate than before.