Bad speedo or cable?

[wcorbett]

Now that I'm driving the truck more regularly, some age issues are popping up. Occasionally heard a a noise that was behind the dash intermittently. Driving down the road today, suddenly a high pitch squeal under my feet, speedo was bouncing at the 100 mph mark( no I wasn't actually going that fast), stopped the truck, and the speedo stayed pegged past 100. Disconnected the cable at the trans first ( no change), then disconnected behind the dash (no change). Speedo is now pegged all the way to the right. So, is the speedo toast, or can I reset it somehow and replace the cable and be good to go? Thanks for any help?

[chevy_mike]

Had something similar happen in my '65 truck. Had to replace the speedo unit as it ended up snapping the needle off. Luckily I had a spare cluster.

[63burban]

We do it the old fashioned way and take things apart to diagnose the problem, difficult to check it out from here.

[Cape Codder]

Originally Posted by 63burban

We do it the old fashioned way and take things apart to diagnose the problem, difficult to check it out from here.

Nothing can be condemed till taken apart even if it can[t go back together

[69chevytrucker]

check the driven gear in the trans they pile up and do funny things

[jtrichard]

Originally Posted by wcorbett

So, is the speedo toast, or can I reset it somehow and replace the cable and be good to go? Thanks for any help?

YES TOAST .....The needle shaft has seized (Lack of lube 50...years go figure) to the main input in the speedo head it needs to be rebuilt or new mechanism

[vince1]

I think the needle is connected to a magnetic drag cup with a spring to always pull it back to zero. It has obviously gained traction from the turning piece inside it going wonky.