General Swaybar Info

[mahout]

Anti-roll is merely another suspension technique that offers reduced body roll with softer springs for good ride comfort. (and tire contact)
In general the stiffer the springs the less antisway bars needed.
The advantage of stiffer springs with less anti=sway in the inside wheels stay in better contact with the ground though the rougher the ground the more likely the tire doesn't stay in contact the stiffer the spring. (staying in contact means the car is in control; not in contact the car is out of control and no thrust either)
As long as the center of gravity is constant (at rest) physics will easily show you that the higher the centrifugal force (i.e. speed on a radius) the more the vehicle weight is transferred from inside the radius to the outside wheels. As the weight transfers the contact area of the inside tire decreases and only slightly increases on the outside. Cornering power is determined by the coefficient of friction between the tire and ground and the area in contact.
The purpose of the suspension system is first to achieve the maximum area of contact between tires and ground and to maximize the aggregate pressure
on the contact areas. That is a simple statement covering a very complex design situation. That said:

More anti sway is not necessarily a good thing. Stiffer springs is not necessarily a good thing.. Lower center of gravity is not necessarily a good thing.
The optimum combination of those 3 things is a project that drives Cray computers nuts.
First, lower the CG reasonably, taking into ground clearance and ground roughness is paramount.
Second chose springs that match the change in spring lengths per unit time. Shocks are used to assist in that control of spring length changes.
The more change per unit time the softer the spring, the less change the stiffer.
Antisway is a tuning device more than anti-roll. Think of the CG as a line running thru the vehicle front to rear. At the front it is between the front wheels and at the rear between the rear wheels. One is virtually always higher than the other, hence the line tilts, up and down and actually side to side, hence its diagonal to the vehicle. Except on F1 etc designed vehicles it is rarely a horizontal line midway of the car. The purpose of antiroll bars is to make the line more horizontal and midway front to rear. For example on a basically understeering FWD vehicle that line is high and left of center at the front and less higher and more midway at the rear. There needs to be reduced understeer at the front - meaning less antiroll - and more oversteer -more antiroll-at the rear so that if the vehicle slides the front and rear break loose together. And equally. Well as close as possible.
Street FWD cars used on track generally benefit from less antiroll front and more or no less antiroll at the rear. Often the springs are tuned the same way. Softer springs front and stiffer rear to avoid too much or too little spring stiffness.
Really stiff antisway bars may feel great on the street but in competition they will be slower purely because they 'tip' quicker, losing traction, thus sliding around instead of cornering. Don't let ESPN's lurid scenes of sliding dirt trackers fool you. They only do that because they have no traction and are merely balancing all that dirt throwing with thrust in a predicted direction.
Generally we have found a little stiffer spring and no antiroll bar at the front and keping the rear antiroll and spring stiffness along with about 1" lowering is the best combination for both street and track.Thats on more than 30 showroom stock racers in 50 years. And tunable shocks are virtually manitory for fine tuning.
Its not an easy result and usually takes many hours of testing. NASCAR, anyone?

[mahout]

First, its not how large the antisway bar is, its how much torsion it generates. The material and shape are large factors in sway bar design as well as diameter and lengths.
The need and design of an anti-roll bar is not magic. It used to be tough til computers came along. Any decent autocad or similar program will do it.
The parameters are the weight distribution supported by the points connected by the antisway bar, the track width, the location of the center of gravity for the weight, and last but far from least, the suspension design - the pivot locations, arm lengths, angles, spring rates, etc.
Once the positions of the tire treads are located with this program based on the lateral forces (centrifugal forces) the anti-roll forces can be substituted on each side to have the maximum tire contact determined. Change the suspension spring and recalculate the needed antiroll forces. Not surprisingly, the antiroll forces often are not the same on each side, though for easier application we often do make them the same. Where these increased limits are employed you will often find that the support brackets for the antisway bar are not evenly distributed across the chassis.
Having found a good starting point, as was said earlier, now a good deal of (experimental adjustment is needed, and having adjustable antisway is as important as adjustable shocks or spring seats.
Most of the adjustment however, comes by balancing the front and rear antisway bars, which is really the important use of antisway bars: to make the slip angles at the front match the ones at the rear IN THE MANNER YOU WANT TO ACHIEVE THE HANDLING THE DRIVER IS MOST COMPETENT WITH.
Is that easy? Of course not; a good suspension team can work 24 hr/day, 365 days/yr and still not get win a NASCAR race, much less an F1 race. (theoretically winning a NASCAR race should be a trifle easier than F1, all other things equal) But only a small trifle.
And for the foregoing reasons just substituting 'bigger' bars, i.e. larger diameter bars can easily work against you as the centrifugal force overcomes the spring force sooner causing the inside tire to clear the pavement sooner and your car losing sidebite - thus traction, sooner, and your cornering speed is reduced. Not to mention that end of the car may not balance with the other end, leading to more oversteer or less. That may not be a good thing.
In other words, flatter may not be better. cheers.

[mahout]

Antiroll, or antisway, or sway bars, can be rods (solid), tubes (hollow) and of many metals, shapes, and uniformity (collapsed bends); they can be adjustible (threaded, pinned (thru bolts), or non-adjustable. They also can have variable length arms, which are a different adjustment, and can have an angle between the two arms.
Strut bars stiffen the body/shock tower geometry and can certainly affect both ride as well as cornering - and neither is guaranteed to be an improvement.
cheers.

[kennman]

Does anybody know (Mahout maybe?) what exactly is the material the swaybars are made of? I mean I know it's spring steel, but what spring steel exactly? How much carbon is in it? What's it called? I heard something like 4340 alloy...
I'm having made a custom swaybar and would like to know as much about the material as possible.
thank you all!
Kennman

[mandarin77]

I have read all the previous responses to this forum. We all get the general idea of how it works. But the descriptions and details of "what changes do I need to make to accomplish particular goals" are very difficult to decipher.

Could someone (no offense) in correct grammar english explain what changes can be made to the 1: sway bar 2: strut 3: spring 4: tower brace 5: ride height
with respect to a) front and rear, and b) what these changes accomplish and finally c) what is given up by this change.

i.e.
1a. stiffer front sway bar gives 1b result and sacrifices 1c.
1a. SOFTER front sway bar gives 1b result and sacrifices 1c.
1a. stiffer REAR sway bar gives 1b result and sacrifices 1c.
3a. stiffer rear spring gives 3b result and sacrifices 3c.
etc.

I hope someone can help me out here.
thanks
mandarin