1938 LaSalle Production - GM Heritage Center

ing surface of cast iron moulded to a strong steel back
plate. These drums, in addition to self-energization,
permit the use of hard durable linings and extend the
life and dependability of the brakes. Total brake lining
area for LaSalle and Cadillac Sixty is 220 sq. in. Lining
area on the Cadillac V-8 is 246 sq. in. and on Fleetwood
258 sq. in. On all models brake lining area is
much greater than on any other cars of similar size
with the result that brake lining wears far longer and
cost to owners is far less.
Braking ratio is 54¾% front and 45¾% rear on
LaSalle and Cadillac Sixty; 57% front and 43% rear
on the larger Cadillacs. The reason for larger cylinders
and drums on the front wheels is because of the tendency
of car weight to shift forward on deceleration increasing
traction on the front wheels. This action is thereby
utilized to increase braking effectiveness.
Duo-servo brake action, or self-energization, is used
because this method permits the use of hard molded
linings of longer wearing life and provides greater ease
of brake operation than can be obtained with a small
amount of energization. The self-energizing principle
involves a conversion of the car's motion, whether in
forward or reverse direction, into additional braking
energy. Brake shoes when applied tend to wrap themselves
into tighter contact with the drums, thereby providing
maximum braking energy with a minimum of
pedal pressure. Both brake shoes float within their
drums so that each can adjust itself to the drum giving
equal pressure around each brake shoe. Both shoes are,
therefore, effective in stopping the car whether in
forward or reverse speeds, and the entire brake lining
contacts the drum, thus wearing evenly and prolonging
its life.
In another method of hydraulic braking which claims
no self-energization, both shoes are anchored to the
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