In the early 1930's when it came time to replace the Type A with a more
modern design, André Citroën investigated all the automotive innovations
with which leading-edge designers were experimenting. Citroën was friends
with an American engineer named Edward Budd, who had made the first
vehicles whose design eschewed any wooden materials and were constructed
entirely of metal. Budd had a concept for doing away with the chassis and
making vehicles completely of sheet metal body "shells." American
manufacturers were not adventurous enough to attempt implementing such a
radical design, but Citroën was intrigued. From the start, he designed his
new model to be based on this experimental method.
Citroën also solidly embraced the concept of front wheel drive as a
more logical and practical means of propelling an automobile. The newly
innovated constant velocity joints made this possible. Citroën devised an
all-new configuration whereby the transmission would be mounted in
front of the engine block, with half-shafts extending out
to the front drive wheels. This consolidated the entire drivetrain at the
front of the vehicle, and eliminated the need for a drive shaft extending
aft, as well as the heavy and cumbersome rear differential. This also
allowed the car to be designed with unparalleled interior space relative
to the exterior dimensions.
In addition to this, Citroën recognized the torsion bar as a more
space-efficient alternative to the coil or leaf spring. He also felt that
it gave the vehicle a better ride and more responsive handling. He decided
to use torsion bars on both the front and rear suspension. Cars of the day
routinely had independent front suspension, but the rear differential was
always implemented as a rigid unit. Having avoided this pitfall, Citroën
was able to make his rear suspension independent as well. The final design
incorporated four-wheel independent torsion bar suspension.
