Calculate final drive ratio by multiplying the axle ratio, transmission gear ratio and transfer case ratio, or solve any one ratio from the others.
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Final Drive Ratio Formula
The following formula calculates overall engine-to-wheel reduction for the selected transmission gear and transfer-case range. The axle final-drive ratio is one factor.
- Where DR is the overall engine-to-wheel drive ratio (ratio :1)
- AR is the axle ratio : 1
- TR is the transmission gear ratio : 1
- TCR is the transfer case ratio : 1
To calculate overall drive ratio, multiply the axle final-drive ratio by the selected transmission gear ratio and transfer case ratio. Use 1 for no transfer case or a direct-drive range.
Final Drive Ratio Definition
The axle final-drive ratio is the reduction between the differential input and the driven wheels. Overall engine-to-wheel ratio also includes the selected transmission gear and transfer-case range, assuming no clutch or torque-converter slip.
Final Drive Ratio Example
How to calculate the final drive ratio?
- First, determine the axle ratio.
For this example we will say the axle ratio is 5:1.
- Next, determine the transmission ratio.
For this example the transmission ratio is 2:1.
- Next, determine the transfer case ratio.
This example uses a direct-drive transfer-case range of 1:1; use your actual selected range.
- Finally, calculate the overall drive ratio.
Using the equation above we find the drive ratio to be 10:1
FAQ
Axle final-drive ratio is one stage of drivetrain reduction. The product calculated here is the overall engine-to-wheel ratio for the selected gear and transfer-case range, assuming no slip.
