1979 C3 speedometer noise and indicator vibration
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Joined: May 2016
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From: Tolland Massachusetts
1979 C3 speedometer noise and indicator vibration
When I purchased my C3, the speedometer was apparently working correctly. I noticed the speedo cable was hanging below the frame. I had my mechanic replace it with a cable of correct length. After that, when the car is cold, the speedometer needle vibrates wildly and there is a mechanical grating noise now occurring. When the car is warmed up, the needle gyration subsides as does the noise and the speedometer seems to be indicating the correct speed. The car has The Cruise control option which does not work. I had a different mechanic look at the problem and he thinks the issue is the transducer. It would be “nice” to restore the Cruise Control function but I really want to get rid of the speedometer vibration and noise. Any advice Forum members can pass on would be very appreciated. Thank you in advance for any help you can give me. One caveat is that I’m not particularly mechanically inclined. I was able to replace the rugs in the car but that required no mechanical abilities. Thank you all. Phil
Le Mans Master
Joined: Aug 2017
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From: Cool Northern Michigan
When Cruise Control is optioned, two different cables are employed. The "lower cable" goes from the transducer to the tranny. The upper unit, from transducer to the back of the speedometer. The lower unit is easy to remove and lube. The upper? Not so much.
More than likely, the cable was not lubricated before installing. You will need to get the front end up on ramps. Using pliers remove each end of the lower cable. Then remove the cable from the sheath by pulling it straight out. Using a high temp thick grease like Hoppes gun grease apply just enough to make it happy. Put it all back together. Just snug the retainers with pliers.
If you wish to by-pass the transducer, you will need to order the longest cable labeled: non-cruise control.
More than likely, the cable was not lubricated before installing. You will need to get the front end up on ramps. Using pliers remove each end of the lower cable. Then remove the cable from the sheath by pulling it straight out. Using a high temp thick grease like Hoppes gun grease apply just enough to make it happy. Put it all back together. Just snug the retainers with pliers.
If you wish to by-pass the transducer, you will need to order the longest cable labeled: non-cruise control.
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Joined: May 2016
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From: Tolland Massachusetts
Thanks, U.P. I think the most expeditious approach is to buy the long cable and bypass the transducer. Do you know how I can obtained n the longer cable and from whom? Thank you again. Phil
Thread Starter
Advanced
Joined: May 2016
Posts: 95
Likes: 7
From: Tolland Massachusetts
Thread Starter
Advanced
Joined: May 2016
Posts: 95
Likes: 7
From: Tolland Massachusetts
Member Since: May 2016
Location: Tolland Massachusetts
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DefaultThanks, U.P. I think the most expeditious approach is to buy the long cable and bypass the transducer. Do you know how I can obtained n the longer cable and from whom? Thank you again. Phil
Melting Slicks
Joined: May 2015
Posts: 2,365
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From: Cape Girardeau Missouri
Not sure about the grease advice for the cable. Willcox and others say that grease will follow the spirals in the cable up into the speedometer which it will ruin.
I suggest spray graphite. Start spraying at the top and continue until you see some liquid from the bottom. Graphite is an excellent lubricant in such an application because it's extremely slippery irregardless of temperature and is essentially eternal in a closed environment.
I suggest spray graphite. Start spraying at the top and continue until you see some liquid from the bottom. Graphite is an excellent lubricant in such an application because it's extremely slippery irregardless of temperature and is essentially eternal in a closed environment.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
I believe I found my long cable at Corvette Central. You need Non-Cruise, so it will be a little longer, by-passing transducer.
When you are ready to install one end through the firewall, have a helper pull the old cable out and insert the new one for you. Its a son-of-a-gun to get your hand up in behind the speedometer and slide the tab to unlock the old cable. Then lock the new one in. Prepare for moocho swearing.
Don't worry about gun grease on the cable working its way up to the firewall, too thick. If you use oil, its too thin and will travel up the sheath.
When you are ready to install one end through the firewall, have a helper pull the old cable out and insert the new one for you. Its a son-of-a-gun to get your hand up in behind the speedometer and slide the tab to unlock the old cable. Then lock the new one in. Prepare for moocho swearing.
Don't worry about gun grease on the cable working its way up to the firewall, too thick. If you use oil, its too thin and will travel up the sheath.
Last edited by HeadsU.P.; Mar 14, 2020 at 06:41 PM.
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