1977 speedo stuck at zero

[Michael B.]

After a long winter hibernating I took out the 77 for a test drive today. All went well except the speedo stayed stuck at zero.
No unusual noises, just not moving (didn't look if the odometer advanced).

This was a donor speedo used to replace a failing head last year and worked fine through the season. Is this something where the mechanism may come to life again as it gets used or is this one done for ?? I'm used to seeing needles bouncing and screaming at me. Never seen one just die.

Thanks for any guidance

Michael B.

[Michael W.]

Re: 1977 speedo stuck at zero

Did you check the cable ends?

[Michael B.]

Re: 1977 speedo stuck at zero

Hi Michael

Wish it was that simple. However, the tranny end is on a 90 degree adapter and the speedo end the flange feels like it's not seated completely against the head so maybe the cable inside is not pushed all the way in. I'll check both further.

Cheers.

[Michael W.]

Re: 1977 speedo stuck at zero

If the odo or trip is registering, the fault is internal to the speedo head. If nothing is working, it's some where in the cable or gears. If you have cruise, it's common for the sensor unit in the middle of the cables to seize and snap the input.

[Michael B.]

Re: 1977 speedo stuck at zero

Just wanted to close this loop since it could affect others with a similar setup.

I use the 90 degree adapter for the speedo cable. There is a brass/bronze bolt that faces outward that has gone AWOL.

The body of the adapter is black and so was the grease so initially I didn't notice. At the point where the adapter faces in and held in by that bolt is a pin that takes the place of the cables square pin going into the tranny. With the bolt gone the pin decided to depart at some point as well leaving no connection.

CHECK THAT BRASS BOLT. The side facing into the tranny also holds a brass bushing that centres the square pin. If the pin is gone make sure to find that bushing so it doesn't eat up anything when it's loose. Hopefully mine didn't eat the gear inside but at least I know what's gone wrong.

Cheers.

[David H.]

Re: 1977 speedo stuck at zero

Thank you for posting a follow-up / conclusion message. Really helps the next guy.