T = Torque

Any positive number (decimal optional)

R = Ratios

A decimal between 1 & 18
A decimal between 1 & 5
A decimal between 1 & 5

E = Efficiencies

A decimal between 0 & 1
If unknown use 0.95
A decimal between 0 & 1
Use 1 if not applicable
If unknown use 0.90 for automatic | 0.95 for manual
A decimal between 0 & 1
Use 1 if not applicable



Use the number calculated above in the series selection.
Series functional torque limit must be greater than the number calculated.


All calculations are provided for mathematical & informational purposes only.
DCJ, Inc. makes no claims to the correctness or appropriate use for any specific vehicle.


*Low gear ratio is always a forward gear ratio and is normally 1st gear. Some transmissions will provide a significantly higher numerical 1st gear ratio (i.e. > 18.0). Please contact us or refer to Dana’s & Cummins – Meritor's guide for the qualifications for using 2nd gear for this calculation.

**These efficiencies are referenced in Dana’s driveshaft application guidelines. We have also provided Cummins – Meritor, which differs for these numbers, as well as max driveshaft torque threshold.