Document Y9wVRDaoGaMyeb5BjQYxrb2BO
NAPA AUTOMOTIVE CAREER TRAINING
Master Cylinder (Tandem)
Dual system (tandem) master cylinders have been vehicle's dash panel signaling a loss of pressure in one
used on some American vehicles since 1962. Starting part of the system. The other part of the system will
with 1967 models, dual system master cylinders are remain operational.
used on all American made passenger cars and light
trucks.
Tandem master cylinders are also used for disc brake
equipped vehicles, with the exception that the fluid
The operation of a tandem master cylinder is basic reservoir is much larger. In addition, the output port
ally the same as a single system master cylinder. The to the disc brakes does not contain a residual check
dual unit, however, has two pistons, two separate valve.
fluid reservoirs, and two output ports. Each piston
has a primary and secondary cup, but there is an Internal conditions of corrosion, rusting and pitting
additional secondary cup on the secondary piston make it necessary to overhaul the master cylinder.
which isolates the two hydraulic systems.
Frequently master cylinders are overlooked because it
is thought that they are not subject to the same high
Thus, the tandem master cylinder has two separate temperatures found in the drum brake. This is not
hydraulic pressure systems. One of the systems nor true today, as engine compartment temperatures
mally is connected to the front brakes and the other become quite high. With every brake job, it is highly
is connected to the rear brakes.
recommended that the master cylinder be either
rebuilt or replaced.
When one portion of the system loses pressure, a drop
in the brake pedal will result, alerting the driver of
the loss. This will also activate a warning light on the
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