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Old 09-26-2019, 10:38 AM   #1
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Wonky Speedometer in '67 C10

The speedometer in my '67 C10 (250CID with TH350 transmission; stock gauges) seems to have developed a "bounce" that appears mostly during the first ten or fifteen miles or so, after which time it starts to operate smoothly.

I would imagine that the cable needs lubing or replacement, or maybe the problem is in the speedometer gauge itself, or maybe at the transmission end.

Should I just bite the bullet and change out the cable for a new one? If I choose this route, should I lube the speedo gauge while I'm at it? Any good videos available on how to solve the problem? Any advice would be appreciated.


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Old 09-17-2020, 05:54 AM   #2
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Re: Wonky Speedometer in '67 C10

It may just not be fully seated in the head or transmission. I would try checking both ends first. If that is not an issue removing the cable is not that difficult. Take it out, check the ends for wear, pull the inner cable out, check for kinks, clean, lube, reinstall.
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Old 10-12-2020, 10:18 AM   #3
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Location: Oregon
Posts: 73
Re: Wonky Speedometer in '67 C10

In my experience I have found speedo cables needing to be lubed and rust in the speedo head itself...

Easy to lube the cable, the grease gets dry and the inner drive springy wire can jump around a bit till the lube warms up or becomes smooth.

When the speedo head gets rusty it allows the metal drum to come in contact with the magnets. Should be no contact at all - I'm sure you can find more info about the inner workings of a speedo.

When this happens you may be able to hear a tinging or slight bell like sound as the speedo jumps around.

Hope this helps a bit,

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