Howdy all,

This is my first post in the tech area, so bare with me. I just picked up a '65 coupe with a 302/4sMT with a 4:11 rear gear. The car originally had a 2:80 rear gear when it came out of the factory. My problem is that when I was bringing it home, the speedometer was showing about 90 MPH in 3rd gear and about half throttle. I know this is not exactally correct. What I need to know is if anyone knows what speedometer drive gear I should install to at least get the speedo to read somewhat correct.....it all has to do with the cops and highway patrol thing ya know. And yes I'll post some pics as soon as I can get the wheels back on it.

 

Give this a try

Speedometer Calculator

 

You're likely going to need to change the drive gear (not the driven gear) inside the tranny, which requires removal of the tail shaft. Hopefully, your tranny has a removable drive gear....

 

Yeah its looking like your right. It looks like the drive gear on the transmission tail shaft is a 7 tooth gear (due to the 2:80 original rear gear) and using the calculator it would take a 23 tooth driven gear....they dont make those. So I'll have to look for a 6 tooth drive gear to go with a 20 tooth driven gear. Darn this is fun aint it!?!?! But hey...why else would we put ourselves through all this if we didnt love the car.