M38a1 Speedometer cable slipping in speedo drive

[JayO]

Hello everyone my M38A1 speedo is not registering. The cable spins at the speedometer end when vehicle is in motion It appears that the driven rod in the speedometer cable is not making mechanical contact with speedometer connector. The cable screws tightly to back of speedometer.

Could the speedometer cable driven rod worn out the speedometer drive unit.? I really appreciate your thoughts. The female part of speedometer is round. No traction. You can spin by hand the speedometer and it works. Jay. London Ontario

[wesk]

Does your speedo inner cable look to be 60" long and have the two ends shown on #3 in this photo?



If you have an old speedo inner cable chop of the 3" at the squared off end and chuck it in an electric drill and slide it into the speedo till it bottoms out and run the dril CCW. Does the speedo needle rise and fall smoothly?

We often use what we can find for parts and the M38 speedo cable assemblies came in two flavors. Make sure you don't have an improper cable assembly or a mix & matched cable assembly.



The early M38 assembley is 2" shorter than the late. The late assembly is also used on the M38A1. If you end up with the long outer casing and the short inner cable your speedo will not have enough inner cable engagement.

[JayO]

Wes, thank you very much for your comprehensive reply. I suspect I have the wrong cable as you suggest. I will go back and see who I bought it from. No question my speedo works when spun. Your knowledge is very much appreciated. Jay