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Old 09-12-2002, 10:50 PM
bobbyv bobbyv is offline
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Join Date: Aug 1999
Location: ajax, ontario, canada
Posts: 773
larger sway bars have no effect on pairs of wheels that are moving up and down at the same time, e.g., while moving over railroad tracks at the same time. And unlike stiffer front springs, swaybars do not have any effect on brake dive.

the obvious effect of sway bars, as you already know, is to increase roll resistance.

What is not so obvious is that the tuning of the front vs rear swaybars (among other things) has a big effect on handling:

- A stiff front swaybar tends to increase understeer (Porsche 911s have stiff front swaybars to compensate for the rear's tendency to oversteer; that's why you see pictures of these cars doing extreme cornering with the inside front wheel lifted).

-To reduce understeer, one would increase the stiffness of the rear swaybar. This is usually done for example on front-wheel-drive cars, and it is not uncommon to see them lifting the inside rear wheel during hard cornering.

I believe that swaybar tuning for a front-engine, rear-drive car is tricky: such a car would normally understeer because of the heavy front, and one would normally increase the rear swaybar stiffness to counteract this. But using a stiff rear swaybar would reduce the grip of the inside driven wheel during hard cornering while accelerating.

While one would tend to use stiffer swaybars for performance-oriented driving, there is a point of diminishing returns: for example, if the swaybars were so stiff that the left wheels do not move up and down relative to the right ones, during a hard lefthand corner, the vehicle would still roll because of the laws of physics, but the left wheels would completely lift off the pavement (or just reach that point when they are about to do so, at which point they lose all grip), and all your grip will be limited to your right tires.

on F1 cars for example, they reduce rollbar stiffness when it is raining, to increase mechanical grip. And they vary the front vs rear stiffness as they use up fuel.
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