CJ3B Speedometer Spins Wildly

Speedo cable was broke when I got the Willys. I replaced with new cable. New cable worked fine for the first little while but now it’s fine below 30 mph. Over that especially around the 40 mph mark the needle goes bezerk starts jumping, makes noise and spins clockwise back to 0. If I let off on the gas and get it back to 30 mph it settles down and operates normal until speed goes up and then the needle jumps and spins wildly again. I checked fittings on speedo at both ends. Both are tight. What can I do?

Gerry, it sounds like the speedo head needs maintenance. Theirs a place called Bob's Speedometer https://www.bobsspeedometer.com/1/120/index.asp that might be able to rebuild it. I think Larrbeard knows a place, he might pipe in here. After some research I ended up with a vintage reproduction. The cost to have mine rebuilt and the warning that it might not last, drove me to that decision. I kept the original but you really cant tell them apart.

I used Bob's Speedometer for the '48 Truck speedometer. They are good, they will fix a problem with no quibbling or bickering, fixes for problems go to the head of the line, they communicate well but they are not cheap. As the old farmer said - even hay is cheaper if you can use it after the horse is done with it.

Like most Jeep issues, any one of several things could be the problem.

After Bob's had rebuilt my speedometer, I had a similar issue and it turned out to be a very small kink in that armored cable housing from the transmission to the speedometer head. I finally bought a housing and flex cable from KWAS and all is nice now.

Welcome Gerry,

I have had the same issue until late. I had put in a recycled cable from one of my donors after the original cable gave out. The slightly used cable worked for a time, then the speedo started bouncing at a constant speed. I bought a new cable from one of my trusted suppliers and everything settled down nicely. Some new cables are not lubed, and work fine on the bench. When you install the cable, they bind in the protective sheathing when routed correctly. Also, check to make sure the cable ends are not too long, causing a bind on the transfer case speedo gear. It isn't that unusual to have to trim an 1/8" off the square drive of the cable to prevent the cable from bottoming out in the gear. The link bellow is of the speedometer cable that I am happy with in terms of quality.

https://www.ebay.com/itm/Speedometer...-/271430170830

Unlike several other instances, a speedometer cable that is almost too short works better than one just a little too long!