Dynaflow
[1] The Dynaflow, which was introduced for the 1948 model year only as an option on Roadmaster models, was based on similar principles as those applied for the Torqmatic transmission used in the M18 Hellcat tank destroyer (built in Buick's Flint Assembly plant) and M26 Pershing tank during World War II, namely a multi-element torque converter and manually selected intermediate gears.
The transmission initially used a five-element torque converter, with two impellers and two stators, as well as a planetary gearset that provided two forward speeds plus reverse.
Exacerbating the situation was the dual stator arrangement, which wasted more power than the simpler three element converters used with other automatic transmissions, such as Chrysler's TorqueFlite.
Moreover, Buick's torque tube "live axle" rear suspension design, which incorporated a rigid drive shaft with just one single universal joint ("U-joint") at the front end of the driveshaft, was said to amplify the harshness of contemporary automatic shifting transmissions.
Dynaflow's smooth but inefficient five element torque converter which fed power through a non-shifting direct drive (plus one manually selectable "Low gear" of 1.8:1) was the conceptual polar opposite from the Hydra-Matic used by its sister GM divisions Oldsmobile, Cadillac and then Pontiac.
Dynaflow's inefficiency earned Buick a reputation as a “gas hog” even when compared to heavy, powerful luxury cars of the 1950s and early 1960s.
But at the time, gasoline was cheap, emissions concerns were nonexistent, and Buicks were upscale cars, so the "gas hog" reputation was not a serious sales deterrent.
Arguably, a Buick “family car” wouldn't fare well during the teenage son's weekly “date night Friday” outings.
The Dynaflow aural experience was similar to that of a Continuously Variable Transmission (CVT) (though modern electronically controlled CVT's address this throttle position dependent engine speed (and sound) characteristic by artificially inserting stepwise ratio changes instead of a truly continuous or constant rate change in order to simulate more driver-satisfying genuine shifts).
While these changes improved the transmission's overall performance and efficiency, the Dynaflow still was no match for other designs that utilized three element converters with automatic shifting.
The stator element of the torque converter has two blade positions, controlled by the driver via the accelerator pedal to offer a 'passing gear' and extra response at any speed from heavy throttle application.
A few identifying features: the older Twin Turbine model was fitted with a rear pump, which meant the vehicle could be push-started (considered desirable at the time).
It did not have a manually selectable low gear (the only kickdown mechanism being the variable pitch stator), and had a shift quadrant that read P-R-N-D-G (where "G" stood for "grade retard").
The grade retard feature was not designed as a low or forward acceleration gear and was meant to be used only on long declines to generate a degree of engine braking.
