font-awesome-animation/scss/shake.scss

$faa-shake-speed: 2.5s;
.faa-shake.animated,
.faa-shake.animated-hover:hover,
.faa-parent.animated-hover:hover > .faa-shake {
  animation: wrench $faa-shake-speed ease infinite;
}
.faa-shake.animated.faa-fast,
.faa-shake.animated-hover.faa-fast:hover,
.faa-parent.animated-hover:hover > .faa-shake.faa-fast {
  animation: wrench ($faa-shake-speed * $faa-speed-coeff-fast) ease infinite;
}
.faa-shake.animated.faa-slow,
.faa-shake.animated-hover.faa-slow:hover,
.faa-parent.animated-hover:hover > .faa-shake.faa-slow {
  animation: wrench ($faa-shake-speed * $faa-speed-coeff-slow) ease infinite;
}