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Speedometer Failure

1st vette

Active member
Joined
Dec 27, 2004
Messages
27
Location
Chicago
I was driving home this evening, and watched my speedo needle fall to the stop post while going 60mph. This cannot be good. Anyway, the tach. still works. It's a 1980. Is changing / repairing the unit difficult, and who can do it???


Thank You in Advance.

Ken
 
B

bmotojoe

Guest
I agree that it could be the cable. I would remove the end from the transmission first and hook up a drill motor and slowly spin the motor as a friend watches speedometer inside. If no movement of needle change rotation of drill. Make sure the cable is fully inserted back into the speedometer head, sometimes the cable will pull out from the head when the cable is pulled from the transmission. If you do get movement I would then look at the speedometer gear. Look closely at the end of the speedometer gear in the transmission. The speedometer gear is just made out of a plastic material. The cable is metal and round but both ends of the cable are square. I have seen the inside of the gear where the cable is inserted wear out so the gear is still turning but the cable doesn’t, again an easy fix. I found the best prices for gears are from the Chevrolet Dealer and usually have them in stock so there is no shipping. If it is the gear just remove it and have the parts department match it up with a replacement.
Brian
 

LVMYVT76

Well-known member
Joined
Apr 21, 2006
Messages
664
Location
springfield, mo
Corvette
1976 medium blue
If you have cruise control, you can disconnect the cable going to the speedometer at the transducer in the motor compartment and have some watch as you spin the cable by hand to see if the needle moves. Then you can pull the bottom cable and check for problems there. It might be in the transducer, but usually not, but still could be. If spinning the cable doestn't move the needle, it could be in the head, but you would need to also check this smaller cable. To do both would require getting behind the dash. I hope it is the lower cable or a gear in the transmission(easier to get to). Anyway good luck with your work.
 

Evolution1980

Well-known member
Administrator
Joined
Feb 25, 2002
Messages
4,302
Location
Cleveland, Ohio
Corvette
ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
Ken, as others said above...

If you have cruise control, you'll have at least 4 potential points of failure since the cable is a two piece.
No CC? ...then a single cable with 2 potential points of failure. This isn't a common problem with the C3, but one that happens nonetheless as evidenced by the people that have chimed in with responses. Hope you find the problem!

IF there is a problem with the speedo and it needs to be fixed/replaced, consider calling John at Red Line Gauges. I and others here have had them do the work on the speedo. Excellent company/guy to work with. Highly recommended! Here's a link to the thread that we had started about Red Lin back in 2002.
 

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