[zitani]

I bought a 1999 Cobra with the odometer reading slow. Example: If the car is going 80 mph, the speedo is reading 20. We do not know if the transmission / gearbox has been changed. The speedometer gear inside the transmission is wine color. It looks lie a 6 tooth gear. We have changed the ECM, and the vvehicle spped sensor. Rear end is original. Tires and wheels are OEM original secifications. Any ideas?

[stlwagon]

Welcome... Let's find you an answer in here.

[flyboy137713]

I am also having the same problem. Speedometer is reading about 20 mph over at cruise. Anyone have any ideas??

[flyboy137713]

Having done a little research on my new purchase, I talked to the previous owner about the problem and found out that he had replaced the OEM 3.27 gear with a 4.10 gear. Not only did make the speedometer read incorrectly, but it also caused the odometer to register approximately 1.2 miles for every mile driven. I checked the distance reading off of mile markers on the highway and off of 2 independent GPS's. I bought a speed cal off of Americanmuscle.com and installed it and now the sppedometer is within 1 mph and the odometer is within about a quarter mile for every mile driven, once again verified by mile markers and GPS's. If anyone has any questions, feel free to contact me.