# Speedometer Drive Gear and Driven GEAR



## timmyg (Jan 2, 2012)

I have a 65 GTO I recently purchased. When I purchased it, the Speedometer cable was missing. The previous owner said that the Speedometer reading was way off, so he decided to remove the cable. I have been to numerous sites on the Internet and I cant seem to determine what Drive gear and what driven gear I need to get the correct Speedometer Reading or close to it. I was hoping maybe someone knows how to determine this and could help me.
Transmission is a Turbo 400
Rear Axle Ratio is 3.73
Rear Tire is P275/60R15 (Approx. 27 1/2 inches Tall) 
I am hoping maybe someone could tell me what color and teeth count are needed for the Drive Gear and the Driven Gear, so that I can purchase them and install them before I put the Transmission back in the car. Thanks


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## leeklm (Mar 11, 2012)

Your best bet may be to first check your speedo with a GPS to determine how far you are off. You can then determine what color of gear is needed based on how much you need to change the reading.


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## 69Goatee (Aug 14, 2009)

Go to tciauto.com and find the speedo gear calculator, input the stuff you know (tire size, gear ratio...ect). Then blammo, it will give the EXACT ratio needed. They may not make gears in the exaxt ratio, but you can get close. It worked for me when I changed the rear gear in DA GOAT.


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## GTO JUDGE (May 14, 2005)

A couple of links for you:

Your answer may be found on the first link 

Speedometer gear usage

Yellow 41 tooth maybe? 

Speedo Gear Selection

Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

The GPS method is a great suggestion, I used that to zero in mine. I am off 2mph at 60mph. Before I was off 18mph. I am spot on until 58mph when comparing speedometer to the GPS. 

:cheers


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