Whenever I accelerate (regardless of the speed range) the speedometer needle locks up at the speed where I "got on it". After the acceleration is ended, the speedo needle either (1) returns to the final speed or sometimes (2) stays locked up until I
rap the side of the speedo panel. I suspect an internal problem on the speedo core, but is it possible the plastic cable takeoff gear inside the transmission is worn or defective to somehow force or thrust the cable into the speedo and block the action? Its a tough job pulling that speedo out because of all the underdash work and my old, sore thumb joints, so I want to explore any alternate possible causes for the lockup other than the speedo itself.

 

Speedo needs rebuild.
Do the tach at the same time.
The entire cluster has to come out. Not hard, just bit tedious.
Doug

 

Doug,
Just thought I would mention....you were very right about the speedo remedy. I tried the gear and the cable (replaced both) but no change, so I let Powl's rebuild the Speedo and it did need a few internal parts. I set me back over $1K, but what the hay. My concerns to let someone else do the removal was justified. The technician swapped two of the inst cluster bulbs (even after I numerically coded all the socket locations with the panels, done when I did the panel removal some 10 years prior!) No biggie, I identified the error and he fixed them. I really balked at doing the job myself this time, damned arthritic joints!.... You are correct, though....Not hard, just tedious! At any rate, thanks!
Fred

 

Most jobs on these cars aren't rocket science but require some detailed attention.....and the instrument cluster wiring on a C1 is one of them. The gauge terminal wires aren't hidden inside ganged plastic connectors (like a C2) and are held on with 1/4" nuts and some of those connections can have up to a couple dozen amps going through them...

I hope you added a 30 amp fuse in series with the black wire going to the ammeter while you were under there - an almost mandatory upgrade for the C1s flimsy circuit protection.

 

I just overhauled my speedometer and Only tried it because because one of the well known speedometer guys wouldn’t sell me a part because he said “you can’t fix it”. I’d never taken the cluster out and had only a casual idea about how the speedometer works. I found an instrument source (D&M Restoration in Greenville, SC. No association other than this purchase) and they helped me understand the workings of the speedometer and sold me the $12 buck part to make it work. It now does. Wilcox website also has a good instructional video. All of the pro’s were quoting pretty high prices, $6-7 hundred or so. Point is if I can do this, I can absolutely guarantee most anyone can. Use the information that’s out there and find a good supplier go slow and take a lot of pictures. I also used the SuperBright website to buy LEDs for all lights (‘62) No fitment issues. Frankie and others have great instructions on cluster removal. Be sure and tag all wires and label all posts (you don’t really want to depend upon the wiring diagram in S-12). Grease the cable, no grease in speedometer, while working and add the breaker on the ammeter. Protect the dash pad when moving the cluster. There is a very small bushing on the speedometer. None of the posts mention it and it will fall out. Now, if you have to replace the first worm gear, it has magnets that come unmagnetized. You’ll probably Need help with that. Calibrate 60 mph at 1000 rpms. I promise, details on the job are available on-line. Jim