body roll...

[Punky]

should be illegal to raise cars! its almost as stupid an idea as breast reductions! the ride is a bit harsh in the escort now, but the cornering and general handling makes up for a sore ass.

[Tumble]

s'not stupid at all..... I got 3 foot stand-over clearance now


\/\/INNER!!!

[RocketmanX]

The stiffness and increase in roll couple isn't always good. It's like all things in automotive or racing, it's a matter of what you're doing and the limits of all the different factors, such as tires compared to power and weight. Too stiff a car will have a ton of understeer, on the other hand a too soft chassis will have too much oversteer and be loose on entry, or have a pendulum effect as Event Horizon stated.
It all comes down to balance between front and rear and takes a lot of years of experience to tune properly. A car that's too stiff and driven into a corner at a given speed of say "N" will understeer and the increaesed roll couple (given that N is too fast for the springs) will actually increase the amount of weight transferred to the load bearing wheel to the point of overcoming the tires ability to grip. Watch an F1 car turn in hard and smoke the LF turning into a tight left hander, all the weight has transferred over to the RF tire. A softer spring, given that it's not too soft as to cause the chassis to bottom out, would allow the chassis to roll more at N speed and not completely unload the LF.
Remember spring rating can ause some confusion here.
If a spring is say a 500 lb. spring that means it will take 500 lbs. to push the spring down an inch. If you apply 1000 lbs. the spring will move 2 inches. Now remember the softer spring will allow more body roll (allowing more of the cintrifugal force to be transferred to body roll and not to the tire patch) but does not make the car actually apply more weight to that wheel (left to right- turning left) through the spring, it sees less than with the stiffer spring. The oversteer happens when the body rolls TOO far and the rear of the car starts to unload too much to the front and the rear gets light. this makes the car want to "swap ends".
A stiff spring will not allow as body roll and the centrifugal force will be applied to the tire patch more due to the fact that the stiffer spring will take more to be compressed.

A good example would be to remove your spring and insert steel bars. It'd be like driving an overweight, undertired tired go-kart. The thing would be up on one wheel all the time.

So-
Too stiff (all 4 corners) the car wont turn well and the rear will have no grip on exit.
Too soft and the car will bottom out and cause the chassis to skip across the pavement or the car will get very "assey" or loose on entry.

In oval racing softer is the way to go because we specialize in turning one direction, but turn that direction WAY better than a road course car could. Of course there's a lot of differenet tricks and techniques to turning left that are obviously unique to a chassis designed to turn one direction only. Our main goal is to keep the weight transfer as close to even, from left to right, as possible on corner entry. Of course the laws of physics say that will never happen we try anyway.

Road racing stiffer is more appropriate because the car has to be able to turn both ways and a compromise (compared to only turning one direction that is) is made in handling to accomodate left and right corners. Most road race cars have to be able to run over curbing and take many differnet bankings and radiuses. This means they have to have a much more "neutral" handling chassis.
Most road race cars also use something called "anti-dive", a particular a frame mounting design that takes away the feel the caster has on the car when turning into the corner. This makes the car feel much more stable to the driver. Anti-dive takes away the extra dive produced by a car setup with perpinduclarly mounted upper and lower control arms where the caster makes the turn in corner actually dive and the opposite corner lift.


Ok, I'll shut up now
I could talk about chassis stuff all day

I could have just said that stiffening passenger cars is usually good becuase they are normally sprung for ride first and handling second. Would have about covered it

[Lowe]

Fantastic post Rocket.