# Calibrating a Speedometer



## Musicmike927 (Feb 22, 2009)

Just bought a 1969 gto. Really nice restored condition but my speedometer is slow. Any help on how to Calibrate it. Do i need a new Speedometer cable or is it something else?


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## geeteeohguy (Feb 2, 2008)

If you have oversized rear tires, that could be the problem. Likely, the plastic gear in the transmission tailshaft needs to be changed to match the gear ratio/tire diameter you're running. A cheap, easy fix, more trouble to find the right gear than to replace it!


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## Eric Animal (Oct 28, 2007)

Mike, post some pics!!!:cheers eric


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## Musicmike927 (Feb 22, 2009)

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## Musicmike927 (Feb 22, 2009)

what is the easiest way to replace this gear?


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## 68greengoat (Sep 15, 2005)

Musicmike927 said:


> ImageShack - Image Hosting :: img2450.jpg
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Nice car.....


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## crustysack (Oct 5, 2008)

very nice looking GTO


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## Rukee (Feb 8, 2007)

Musicmike927 said:


> what is the easiest way to replace this gear?



It's behind a round housing were the speedo cable attaches to the tranny. Remove that round housing to expose the changeable gear. Using a gear with less teeth would speed up the cable, I would guess anyway.
..and yeah, sweet GTO! :cheers


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## Petey D (Feb 14, 2009)

Sweet ride!

I have the same problem, when my speedo reads 60mph I'm actually doing about 75-80. (140km/h. I'm Canadian eh.)

I think its a good indicator that my gears are no longer stock.


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