The transfer case reduction gearset is often never used for its original
intended function, that is, to provide an additional speed reduction
(torque amplification) ratio for the powertrain. This concept allows for
the increased use of the transfer case gearset components to work in
concert with the automatic transmission to increase its ratio spread.
This increase in ratio spread will result in improved launch performance
for the vehicle by steepening the effective first gear ratio of the
automatic transmission. The increase in ratio spread may also provide for
reductions in numerical axle ratio of the vehicle thereby improving the
fuel economy during normal highway operation. The present invention
focuses on a method of shifting the transmission of the vehicle in
accordance with the invention which includes providing a transmission
connected to a vehicle engine having a predetermined number of gear
ratios which are selectable.