DeTomaso Mailing List: June 98, Message #154

"Paul Timko" <thedrol@email.msn.com> Wrote:
Okay, I've read a whole bunch of messages about reducing unsprung weight.  I
hear it is supposed to improve handling.  But how?  All the weight is
supported by the tires, right?
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Paul,
  An ideal suspension system would keep the tires on the road with a constant force through all matter of bumps and turns. If the whole thing (including the tires) had zero mass, this could (probably) be achieved: when you hit a bump, the tire would go up instantly and (with no inertia since there is zero mass) the contact force with the road would be constant. And the passengers wouldn't feel a thing.
  
  In the real world, we have a complex mass/spring/damper (shock) system. Spring and damping occur in the tires and bushings as well as the the springs and shocks. The ratio of the sprung to unsprung mass determines (along with the tuning of this system) how close to the ideal we can come. So ideally, the less unsprung mass the better.

  But, life is not that simple. If a system is tuned for a certain unsprung mass and all you do is change the mass without changing the other elements (spring and damping), you could end up with worse (by some set of measurements) performance. That's one reason adjustable shocks are nice; you can retune the system to some degree.

Richard Barkley