ok well currently i have a 2.73 rear with the 700r4 of course. but im getting a 3.08 rearend this weekend and need to know if i have to change both of the gears or if i can get away with only changing the outter one. anybody know what i have compared to what ill need?

if you have 26 inch tires, with the 2.73 you need a 19 and 40 gear, with 3.08 you will need a 19 and 45

go here and put your info in if you don't have a 26 inch tire http://www.700r4.com/speedoCalc/speedocalc.shtml

is the 19 the one on the inside of the transmission tail?

19 is the outer gear (driven), 40 and 45 is in the tailshaft (drive)

you have it backwards-19 is the one on the shaft and 45 is the driven.

sorry about that i was half asleep, thanks for the correction

ok thanks guys that makes my job a whole lot easier.

Count the number of teeth on the drive gear. Then use this formula to figure out which driven gear you will need. Provided that a driven gear is availabe to give you the correct ratio you will not need to change the drive gear. You may also have to change the driven gear housing if you are going from a 30 to a 40 series driven gear, or the other way around. But this way you wouldn't have to remove the tail housing from the transmission.

20168
---------------------- = Tire Rev. per Mile
Tire Diameter (inches).


# Drive Teeth X Axle Ratio X Tire Rev. per Mile
------------------------------------------------- = # Driven Teeth
1001