Here's the mechanical fundamentals behind it: 
Considering motion in a profile plane, the vehicle is a compound
pendulum. If the front wheels strike a bump, a reaction will be
felt by passengers unless the center of percussion is located at or
near the rear axle. The reverse is true as the rear wheels strike a
bump. A reaction will be felt unless the center of percussion is at
or near the front axle.
As a consequence, good vehicle design places the centre of
percussion about one axle with the center of oscilation about the
other.
Got it off my mechanical vibrations textbook.
