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1981 Speedo stopped working

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Old Jun 17, 2023 | 04:40 PM
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Default 1981 Speedo stopped working

Newbie here; what's the most likely culprit and best way to track down the cause? Worked one day and doesn't the next.
Thanks!
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Old Jun 17, 2023 | 05:31 PM
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Does the car have cruise control?
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Old Jun 17, 2023 | 05:57 PM
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Broken cable or striped drive gear in transmission. Drive gears are plastic. With cruise you have 2 cables. without cruise just the one. All fairly easy to check, lube or replace. You will need to get at the back side of the speedo however.
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Old Jun 17, 2023 | 08:09 PM
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Originally Posted by sunflower 1972
Does the car have cruise control?
yes, it does.
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Old Jun 17, 2023 | 09:01 PM
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Originally Posted by rcpd34
yes, it does.
Originally Posted by 4-vettes
Broken cable or striped drive gear in transmission. Drive gears are plastic. With cruise you have 2 cables. without cruise just the one. All fairly easy to check, lube or replace. You will need to get at the back side of the speedo however.
or you can buy a single long cable to omit cruise
if it is cable issue,
disconnect cable at trans use drill to grip cable, have helper watch speedo, maybe reverse direction,,,
if speedo works then trans gear bad or cruise cable so next at cruise check cable to speedo same way .
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Old Jun 18, 2023 | 06:56 AM
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Originally Posted by calwldlife
or you can buy a single long cable to omit cruise
if it is cable issue,
disconnect cable at trans use drill to grip cable, have helper watch speedo, maybe reverse direction,,,
if speedo works then trans gear bad or cruise cable so next at cruise check cable to speedo same way .
great info; thanks!
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Old Jun 18, 2023 | 10:41 AM
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If you do end up ordering a new cable, you may see several options from Vette venders.
Manual or automatic?
w/ cruise
w/o cruise.
Different yrs?

If you have no desire to incorporate the cruise control, then order the one-piece, longer cable as mentioned to by-pass it.

The reason these cables snap is, it's likely the most neglected part on the car that requires lube. No body does this until issues arise.
Do not use oil. The spiral design of the cable could force oil up into the back of your speedometer cluster. Not pretty.
Use a heavy grease that can handle the heat from the nearby exhaust. Hoopes Gun Grease works well and will not "wick".

The removal of the cable from under the dash is a #3 star out of 5 for "swearing tasks". Have a helper stand at the firewall insert the brand-new lubed cable to you as you disconnect the old one from the cluster.
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Old Jun 18, 2023 | 10:44 AM
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Originally Posted by HeadsU.P.
If you do end up ordering a new cable, you may see several options from Vette venders.
Manual or automatic?
w/ cruise
w/o cruise.
Different yrs?

If you have no desire to incorporate the cruise control, then order the one-piece, longer cable as mentioned to by-pass it.

The reason these cables snap is, it's likely the most neglected part on the car that requires lube. No body does this until issues arise.
Do not use oil. The spiral design of the cable could force oil up into the back of your speedometer cluster. Not pretty.
Use a heavy grease that can handle the heat from the nearby exhaust. Hoopes Gun Grease works well and will not "wick".

The removal of the cable from under the dash is a #3 star out of 5 for "swearing tasks". Have a helper stand at the firewall insert the brand-new lubed cable to you as you disconnect the old one from the cluster.
I’d like to keep the car all original, so I will be retaining the CC. Thanks again.
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Old Jun 21, 2023 | 10:55 AM
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Originally Posted by rcpd34
I’d like to keep the car all original, so I will be retaining the CC. Thanks again.
I have a used lower cable that I just pulled off of my "81.
I have a GPS speedo and deleted the cruise.
I don't need it anymore.
That is if you want a used cable.
Craig
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Old Jun 21, 2023 | 11:52 AM
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Originally Posted by Street Rat
I have a used lower cable that I just pulled off of my "81.
I have a GPS speedo and deleted the cruise.
I don't need it anymore.
That is if you want a used cable.
Craig
Thanks for the offer, but I’ll probably just replace it with a new cable since I’m going to the trouble of removing it.
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