The Stovebolt Site Forums The Shop Area General Truck Talk Bouncing speedometer needle?

I know I've read about this before but I can't seem to find it anywhere with the search.

What causes the speedometer needle to bounce?
I have a new cable and a rebuilt and cleaned speedometer in my '51 3100.

the needle is moved by a magnet, it can only react to the movement of the cable if nothing is binding .... I'd think something would have to be sticky [likely what you recall reading about], unless maybe there was a bad drive gear in the trans

Bill

It spun fine with a drill. The drive gear is what I think I remember reading about.

maybe drive it with the speedo end of the cable disconnected and feel it with fingers to see if it spins smoothly or is jumpy

Bill

You might try unscrewing the cable a bit in case there is a mismatch with the cable length and cable housing length. It might be binding when screwed tight.

Kurt

Thanks Bill and Kurt! I'll give both of these a shot today.

Any thoughts on the drive gear? I vaguely remember reading about it causing the same problem but I still am not finding any info on it.

I think the problem lies in the speedometer head. shoot a little wd-40 inside the cable hole and drive it for a while. Eventually it will smooth out.

Check the cable to make sure it isn't bent at any tight angles - the cable has to spin freely inside the casing.

I loosened the cable at the back of the speedo and it seems to have helped a bit but it's still not 100% I'm going to try a drop or two of naptha on the back of the speedo to see if that cleans things up any.