GPS Speedometer

RPMagoo said
My problem is -- I have a 64 Falcon Sprint (I Know it's a Brand X) with a AOD transmission, 8" rear, 3.80 ratio, and 245/60-15" tires. The speedometer drive gear in the transmission is a 8 tooth and with My setup the correct driven gear is a 23 tooth. -- I haven't been able to get a 23 tooth gear that works without being chewed up. It seems that they all enter into the drive gear at the wrong angle. The max OEM - Ford gear is a 21 tooth. -- Currently I am using a 21 tooth gear, and My speedometer is off by 10%.

there used to be speedo adapters available, which were little boxes which were like 2" long x 1" x 1", and screwed to your trans and accepted the end of the speedo cable. I've seen them made out of bakelite or aluminum. within the box there are little nylon? spur gears, of various numbered teeth, to alter the final ratio in conjunction with whatever speedo ratio in the trans. My 76 dodge w200 came with one from the factory.