Each
time
the
air/fuel
mixture
inside
a
cylinder
is
ignited,
the
combustion
that
occurs
creates
a
torque
spike
that
is
applied
to
the
crankshaft
through
the
piston
and
rod.
This
torque
spike
is
so
severe
that
it
not
only
turns
the
crankshaft,
it
actually
twists
the
crankshaft
ahead
of
its
normal
rotation
and
then
the
crankshaft
rebounds.
This
twisting
action
is
known
as
torsional
vibration.
When
these
torque
spikes
and
forces
get
into
phase
with
the
natural
frequency,
critical
torsional
harmonic
vibrations
occur
and
can
be
seriously
destructive
to
the
bearings
and
the
crankshaft.
Dampers
are
designed
to
control
those
destructive
vibrations.
Critical
harmonic
vibrations
occur
numerous
times
in
a
engine's
operating
range.
Stock
rubber
and
elastomer-type
dampers
are
frequency
sensitive
"tuned
absorbers",
and
work
at
only
one
critical
frequency.
In
the
case
of
a
stock
rubber
damper,
it
is
tuned
for
a
factory
engine's
critical
harmonic
vibrations.
If
you
change
the
mass
of
pistons,
rods,
or
the
crankshaft,
you
change
the
natural
frequency
of
the
crankshaft
assembly;
therefore,
the
stock
damper
is
no
longer
tuned
to
the
new
frequency
of
vibration,
and
you
may
be
headed
for
early
failure
of
expensive
engine
components.
Dampers
also
create
heat
while
they
work,
and
rubber
is
a
poor
dissipator
of
heat.
This
heat
and
the
exposure
to
the
elements
deteriorates
rubber,
causing
it
to
crack
and
change
durometer,
which
then
leads
to
inertia
ring
slippage,
damper
failure,
uncontrolled
torsional
vibration,
and
costly
engine
parts
breakage.