A lot depends on the tires and shock rates, as well as the sway bars and suspension/alignment adjustments.
Typically, a stiffer front bar will cause understeer, and a stiffer rear bar will cause oversteer. This sound backwards. Depending on the car set up, it sometimes is backwards.
The sway bar connects to the suspension on each side of the car, and to the frame.
They have NO affect on bumps, if the bump is equal on both sides of the car. When one tire lifts or drops, the bar twists and tries to raise or lower the wheel on the other side to keep them at the same height. This keeps the car flatter to the road, instead of leaning.
By keeping the car flatter, the tires stay flat as well, allowing the full width of the tread to stay on the road. If the car leans, the edge of the tread lifts, reducing contact, and traction.
But if the bar is too stiff, the suspension is not as active and does not absorb irregular surfaces as well. It can also make the tire interact with the surface of the road differently, changing the slip angle. You will find that a sway bar makes a big difference in how the car handles on pavement cracks and crosswinds.
That's the basics.
But by adjusting steering and alignment angles you can create some of this without sway bars. Then the bars still make a difference, but have a different effect. Typically, if adjustment is use, the tires wear faster. Again this depends on suspension design. The Acura NSX is a great example. To make it handle it's best, it eats a set of rear tires every 8 to 10 thousand miles. Get rid of the wear, and the handling drops way off.
Suspension geometry plays an equally big part. This is something most folks can not, and should not, change. It involves relocating suspension mounting points and making major changes to components.
Geometry can be and is changed by changing ride height. Raise or lower the car and the angles of the suspension move, and change. This can have a drastic affect on the car. A change in ride height of only one inch will change the geometry enough to require an alignment. Some times an alignment will bring the car back to specs, but it does not completely fix the geometry.
Ride height also changes the center of gravity. This is not only due to the acutal weight being raised or lowered, but the change in suspension geometry as well. It changes the roll center of the car, and points where the car piviots on a line through the car front to rear, and side to side. Where these meet is the center of gravity. So where the weight is located, and how it piviots both have a large affect.
Slip angle is the difference between where the tire is pointing and the angle it is traveling. All tires slip. They must slip to develop traction. A free rolling tire has no friction to the surface it's on, and therfore little or no traction. When the tire is flexed, it creates friction and traction.
If the tire is turning more than the angle it's pointed in, thats oversteer. If it's turning less than pointed angle, thats understeer. This is not limited to the front tires. The rear also creates the same forces. The combination of front and rear slip angles create the overall over or under steer of the car as a whole.
Acelleration and decelleration also create slip angles. When you slip you create traction. When you exceed traction limits, the tire spins or slides. This is 100% slip angle.
And when you acellerate or brake you create slip, then add slip from cornering, and it's easy to exceed total traction. But even not exceeded, it changes the operation of the tire.
Any one who has made a car change it's line in a corner by pushing or lifting the throttle has felt this. I'm guessing all of us have done that. A low speed example is driving on ice.
The point is that there are many things that affect the slip angle, including alignment, suspension geometry, shock action, sway bars, spring stiffness, and the tire itself. Thats why some of our cars respond differently than others to the "same" changes.
I never make these easy, do I?
