I have a 65 fastback with the 5 gauge instrument cluster. Sometimes the speedo will go crazy. I will be driving and the speedo will all sudden shot up to 70 or 80 when i'm only going 35. It doesn't do it all the time, so whats the deal? Thanks.

 

start withputting some graphite lubricant in the cable shaft where it connects in the back of the speedo. Sounds like the cable has gone dry.

 

Correction...lube the entire cable. It's possible it's already broken, but not separated.

 

And lube with graphite, not grease.

 

Someone correct me if I am wrong, but I think the speedometer cable attaches to the speedo with a reverse thread nut. So if you are having a hard time removing it try spinning the nut the other way to loosen.

 

Do you mean a left hand thread? No, it tightens clockwise and loosens counter-clockwise.