jedhead said:
If using little or no sway bars is better for handling, then why would the Ninja Turtle SHO's use 68mm front and 83mm rear bars?
I think Hack got it on this one. This would be a 22/26mm combo.
When the sway bar is compressed on one side doesn't it put downward pressure on the other tire?
It's easiest to visualize it this way. When you go around a left-hand corner the spring on the right-hand suspension is compressed. This pulls that end of the sway bar up, which forces the other end of the sway bar up, causing the left-hand corner spring to compress from that force -- eg the swaybar is now supporting some of the weight of the left-hand side now, so there is less weight/force to push the tire against the ground. You've transferred that force to the outside (heavily-loaded) tire.
My 1974 Jensen-Healey did not have sway bars from the factory. I purchased a set of sway bars for it, my cornering speeds increased greatly. The body roll decreased also. The only downside that I had with the sway bar equipped Jensen-Healey was in really roughly paved corners the live axle rear end got upset easier.
In many cases sway bars can still improve cornering speeds because the suspension geometry is retained and the tire has a better contact patch then it would without the sway bar. Also, transitions are indeed faster with a sway bar, and the center of gravity does not move as much.
What I was trying to say (and probably didn't do a real good job of it) is that springs offer you the same benefits -- reduced body roll, better suspension geometry, etc., without the detriment that sway bars bring. Also, there is a point at which reducing body roll has LESS increase (performance-wise) than the grip lost due to the larger sway bar. Note that the car may still *feel* more stable, and faster, because there is less body roll, but if you actually timed the two setups it would not necessarily match what you perceived.
Of course, the detriment with springs is that they (A) Require more damping force, and (B) Degrade ride quality more quickly than sway bars, and degrade it even in straight-line driving over even (eg. same side-to-side) bumps like humps/ripples in roadways.
The newest BMW has sway bars that are two piece and can be disconnected. It is my understanding that the sway bar is disconnected while driving in a straight line for a better ride and connected while cornering. Does BMW have it wrong and the sway bars be disconnected for cornering?
I'm not familiar with their setup, but it wouldn't make much sense to disconnect the sway bars during cornering when that is indeed when you would want them. You probably would disconnect them during straight-line driving because things like potholes and bumps damp better if they stay on one side of the car, rather than being transferred to the other side (which causes the body of the car to attempt to lift or fall because that wheel suddenly has extra force on it above the weight of the car due to the sway bar transferring force there). If you think about the sway bar as an 'anti-independent-suspension' device (links the two sides together), then it makes sense that the ride quality is degraded by installing a larger sway bar.
-Lance
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