I recently added a new wire harness in my '61 and while I was at it, I replaced the speedo and tach cables. I've got it all back together and everything seems to work except the speedo. I'm certain that the cable is fully engaged into the female fittings at both ends. With the cable still screwed to the speedometer, I removed the cable from the transmission end and tried turning the inner cable by hand. Wouldn't turn. I applied a cordless screw driver to the cable and the speedo needle would jump up in the 40 mph range and then fall back after a second or two. It would continue pulsing in this fashion until I stopped turning it with the screw driver. With the cable disconnected from the speedometer and the transmission ends, the cable turns easily. Therefore, I'm guessing that the problem must be inside the mechanism of the speedometer. Before I pull out the instrument cluster (and all the new wiring) in order to remove the speedo, I'm hoping someone might have a thought on what's going on here. I know that the first question should be; "did the speedo work before you did that work?" and the answer is I'm not sure but I believe so. This is a car that is relatively new to me and the former owner is not available to confirm that it was working prior to my ownership. Any help is greatly appreciated.

 

Test all loose not totally bolted down. This is good practice. Someone assumed just because they connected...maybe everything that it all works on these old used cars. Hopefully. Yeah no.

 

you don't have to pull out all the new wiring to remove the cluster, fortunately...but you do have to disconnect all the wires from the cluster.

Have fun!

Rusty did my speedometer recently, it works perfectly now.

 

https://www.corvetteforum.com/forums...5-and-2008.pdf

 

What supplier did you purchase the cables from?

If the speedo was working before the cable replacement I would suspect the new cable is the issue.

 

If you cannot turn the cable by hand when connected to the speedometer, my guess is that there is probably something hanging up in the speedometer. The speedometer is calibrated to indicate 60 mph at 1000 rpm cable speed. The odometer at 1000 rpm cable speed should turn over 1 mile per minute. The odometer is gear driven off the cable. If your speedometer is indicating 40 mph and then jumping down for a second or two, you may have a faulty odometer.

 

The odometer will tend to stick after several decades, and it's hardest to turn when there are several 9s showing. If it gets too bad, it will break the plastic gear inside.

If in doubt, get the speedometer serviced. Save yourself breaking stuff.

 

Thanks to all! I hadn't downloaded the detailed directions on removing the instrument cluster until I had already removed the speedometer. As a result, I did it bass akwards. I pulled the wheel along with the steering column and turn signal bell along with disconnecting the turn signal wiring. The steering shaft remained but after removing the 4 bolts that hold the speedometer cluster in place and disconnecting the 6 speedo bulb sockets and the speedo and tach cables , I was able to remove the 3 bolts that hold the speedo in place. After pushing some of the wiring aside, I was able to rotate the speedometer housing around the steering column and pull it out the bottom. All the other gauges with their wiring remained in place. I found that the speedo mechanism was indeed frozen. I disassembled the unit as far as I felt comfortable but couldn't figure out how to remove the hand from the dial. The speedo is now in the hands of Morris at West Valley Instruments in the San Fernando Valley in SoCal. He's promised to get it back to me by the end of the week. It will be interesting if I can reverse the process and get it back into place following my unconventional procedure. Next time I'll remember to open all the files that everyone was so helpful in providing.

 

The needle is a light press fit on the pin it fits onto. Usually it will pull off if you apply a light twisting motion, while holding the cup from rotating.

But you're probably better off not having removed it, after all