speedo way out of line!!

[miottimouse]

Good day, this 76 custom "logger truck is getting real interesting! I got an Alberta in-transit permit for 3 days to drive this truck for service that I cant get in our little town and took this truck on an 80 km trip to "try her out" before the safety inspection on thurs. I got on the hyway and found the speedo to be reading a lot faster than my road speed. This speedo is still in mph and is reading 80 mph with an actual speed of 60. So it is 20 mph out.
I got home and pulled the speedo cable out of the trans and found a red 16 tooth gear. This truck has a dana 60 4.10 ratio I also checked my 79 s/c that also has the same 4.10 axle and found a longer blue 16 tooth gear.
so my question is: is the 16 tooth red gear correct for a 76 c6 trans? is the internal gears different between a 76 and 79 trans? this has me stumped!

 

[Mil1ion]

Good day, this 76 custom "logger truck is getting real interesting! I got an Alberta in-transit permit for 3 days to drive this truck for service that I cant get in our little town and took this truck on an 80 km trip to "try her out" before the safety inspection on thurs. I got on the hyway and found the speedo to be reading a lot faster than my road speed. This speedo is still in mph and is reading 80 mph with an actual speed of 60. So it is 20 mph out.
I got home and pulled the speedo cable out of the trans and found a red 16 tooth gear. This truck has a dana 60 4.10 ratio I also checked my 79 s/c that also has the same 4.10 axle and found a longer blue 16 tooth gear.
so my question is: is the 16 tooth red gear correct for a 76 c6 trans? is the internal gears different between a 76 and 79 trans? this has me .

http://www.tciauto.com/tc/speedometer-gear-calculator/


http://www.transmissioncenter.org/Ford_Speedometer_Gears.htm

 

[BKW]

Good day, this 76 custom "logger truck is getting real interesting! I got an Alberta in-transit permit for 3 days to drive this truck for service that I cant get in our little town and took this truck on an 80 km trip to "try her out" before the safety inspection on thurs. I got on the hyway and found the speedo to be reading a lot faster than my road speed. This speedo is still in mph and is reading 80 mph with an actual speed of 60. So it is 20 mph out.
I got home and pulled the speedo cable out of the trans and found a red 16 tooth gear. This truck has a dana 60 4.10 ratio I also checked my 79 s/c that also has the same 4.10 axle and found a longer blue 16 tooth gear.
so my question is: is the 16 tooth red gear correct for a 76 c6 trans? is the internal gears different between a 76 and 79 trans? this has me stumped!

Number of teeth on DRIVEN (end of cable) and DRIVE (on output shaft) speedo gears depends on trans type, rear axle ratio and tire size.