Quote:
Originally Posted by Ro_Ja
Isn't that opposite of the theory above? How does RCE do it (and get away with it too?). I understand RCE favors a square setup, which not everyone prefers, but it seems like they make it work and people are generally happy with their way of doing things.
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The theory that many subscribe to that the rear natural frequency has to be ~0.3 Hz more than the front was NOT a theory that was developed to make the car faster around a track. It was NOT developed to produce a "correct" handling balance. It does NOT incorporate swaybars, alignment, tire compounds, differentials, aerodynamics, dynamic suspension geometry changes, drive wheels, etc.
This theory was developed by Maurice Olley in the 1930's. That's a long time ago. It's a guideline that was developed for passenger cars so that the front and rear of the chassis react sort of "in phase" togehter for the initial period after hitting a bump at a specific vehicle speed. This does help the car feel more comfortable. It was a very important step forward and chassis/suspension design...Olley was a very smart and interesting guy.
But passenger cars (perhaps more so on passenger cars 85 years ago) run very low damping ratios...meaning yes, the cycles per unit time (natural frequency) of the suspension may be something you easily feel. Think old school big ass Cadillac bouncing down the road after hitting a bump. It's not something that's felt quite so much on a car with firmer shocks. You hit a bump on a car with proper shocks with damping ratios around the often cited 65% of critically damped ratio and the car settles very quickly because of the shocks. It's not all spring, bouncing and bouncing down the road.
We've felt that rear spring rate and damping ratio has been hugely influential on ride quality and the ability to put power to the ground. When we want to control front roll and limit front dynamic geometry changes as well improve transient response with a certain front spring rate, the flat ride theory would require us to run rear spring rates that are just too high for comfort and rear traction. There are compromises and tradeoffs. We generally don't run spring rates as high as some others.
Every motorsports level suspension engineer has told me the same thing about flat ride. It's a starting point at best. But they don't care too much. The "correct" spring rate balance is the one that makes the car go around the track the fastest.
- Andrew