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Speedo/ Odo Problem

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Old Nov 21, 2020 | 07:01 PM
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Default Speedo/ Odo Problem

How can this be? My speedometer on my '70 works perfectly, but the odometer doesn't work at all! WTF? Doesn't that assembly work together?
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Old Nov 21, 2020 | 07:17 PM
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There are a little tiny plastic gears to make it all work together. One of your little tiny plastic years has failed
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Old Nov 21, 2020 | 07:26 PM
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Originally Posted by Dynra Rockets
There are a little tiny plastic gears to make it all work together. One of your little tiny plastic years has failed
In the transmission or the speedometer?
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Old Nov 21, 2020 | 07:33 PM
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Speedo. If the mph is working then the trans and cable are fine.
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Old Nov 21, 2020 | 07:44 PM
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I suppose this would require the removal of the dashboard. yuk.
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Old Nov 21, 2020 | 08:50 PM
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Check your trip odometer cable, might not be pulled out all the way
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Old Nov 22, 2020 | 12:58 AM
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won't matter. odo is going to turn regardless. unless of course those little plastic gears are stripped. looks like you need a new speedo.
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Old Nov 22, 2020 | 08:57 AM
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Originally Posted by bruiser
Check your trip odometer cable, might not be pulled out all the way
Ya mean there are TWO cables, one for the speedo and one for the odometer?
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Old Nov 22, 2020 | 10:02 AM
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Originally Posted by Ray Romano
Ya mean there are TWO cables, one for the speedo and one for the odometer?
no. there is one cable to the speedo. search this forum or youtube for speedo repair. it is possible to fix yourself but takes patience, good eyes and tiny tools. there are a handful of speedo repair places around the country you can send it to also

Last edited by Dynra Rockets; Nov 22, 2020 at 10:03 AM.
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Old Nov 22, 2020 | 10:31 AM
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Here’s someone that just did this
https://www.corvetteforum.com/forums...rs-repair.html
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Old Nov 22, 2020 | 12:58 PM
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Originally Posted by Ray Romano
Ya mean there are TWO cables, one for the speedo and one for the odometer?
The trip odometer cable is the one you use to reset back to zero. It is below the steering column.
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Old Nov 24, 2020 | 01:03 AM
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I just did this repair.
The issue is the gear in the speedometer, so the dash needs to come out.
The question is not IF the plastic gear is stripped, it's why. The gear is plastic for a reason, and that's to keep the speedometer working if there is binding in any of the other gears.
For me, it turned out the numbered rollers that became frozen because of corrosion on the shaft they ride on.

speedometer removed from dash

speedo removed from face with stability plate removed

you have to use a punch to knock out the retaining bushing that holds the black plastic gear in place

this is the gear that is designed to strip when there is too much binding or resitance in the subsequent gearing


Notice the dark spot on the shaft


The bad thing is removing the dash is a huge pain in the ***.
The good thing is it can be fixed by buying a relatively cheap new gear (numbered 1604) and a lot of time. For the cost of a new speedometer, I would say it's worth trying to do it yourself.
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Old Nov 24, 2020 | 03:03 PM
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You have the ideal situation: Speedo works....but the car never shows more miles of use!!
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