Speedo correction question

[super302]

I was thinking about getting 3.73's, i checked out some web sites and saw that i need a 23 tooth driven gear, i have a 8 tooth drive gear. If you do the math(i think this is how you do it) and take 23/8 = 2.875...which is no where near 3.73. If that is not how you do it how far off would my speedo be with the 23 tooth gear??

 

[Venom4.6]

The 23 tooth will get you closest to what you need. It's not 100% accurate, off by a couple MPH.
http://steeda.com/store/-catalog/speedometer.htm

 

[TRWXXA]

3.73 is the number of teeth on the pinion gear divided into the number of teeth on the ring gear. It really has nothing to do with the number of teeth on the speedo gears.

Hell, you could correct the speedo for new rear end ratios by having a new guage face printed up. The numbers would just be more widely spaced to account for the greater needle deflection at the same speeds. You wouldn't even have to touch the speedo gears.