you are thinking too hard, me thinks.

 

There are several different methods to sways bars. I have heard that our cars suffer from positive chamber gain in the front suspension at the limit, and having a larger front sway help keep that in check. As far as changing both sways, most have a different diameter front and rear. This allows you to increase grip and modify the bias of the car depending on difference between the front and rear bars. I have the rce adjustable front and rear bars. Right now, I have the front full soft (25 mm) and the rear to medium (27 mm). It also depends on what you plan to do. If you run stock class, you can only change/modify the front sway bar, but STU, you can change/modify both.

 

There is some EXCELLENT information in the thread below. Well worth a read.

http://www.iwsti.com/forums/gd-suspension-handling-stiffening/67749-stretchs-notes.html

 

Lots of inapropriate use of termonology occurs on this subject but its all pretty straight forward.

If your car stock can pull .9g's thats a measure of its overall "grip"
Your car stock at the limit will understeer if you try to push it to >.90g's.
Pretty much all factory cars i am aware of are setup this way as oversteer is more dangerous and more of a liability than understeer is.

Adding a front or rear or both swaybar will make that "Grip" number go up, your car will be capable of more g's.
If you put on a rear sway bar only, at the limit the car will have more of a tendandy to oversteer than stock. If you put on a front sway bar only at the limit the car will have more of a tendancy to understeer than it did stock. But either way the grip limit, or g's the car can pull, will move up.

Seen as our cars are generally considered to understeer most people tend to move the bias of bar strength backwards to try to get the car to be more biased to oversteer. Though in all honesty if you adjust your driving style to the car and don't try to do things the car cant do, it's only relivant if you're going 10/10's.

 

Lots of inapropriate use of termonology occurs on this subject but its all pretty straight forward.

If your car stock can pull .9g's thats a measure of its overall "grip"
Your car stock at the limit will understeer if you try to push it to >.90g's.
Pretty much all factory cars i am aware of are setup this way as oversteer is more dangerous and more of a liability than understeer is.

Adding a front or rear or both swaybar will make that "Grip" number go up, your car will be capable of more g's.
If you put on a rear sway bar only, at the limit the car will have more of a tendandy to oversteer than stock. If you put on a front sway bar only at the limit the car will have more of a tendancy to understeer than it did stock. But either way the grip limit, or g's the car can pull, will move up.

Seen as our cars are generally considered to understeer most people tend to move the bias of bar strength backwards to try to get the car to be more biased to oversteer. Though in all honesty if you adjust your driving style to the car and don't try to do things the car cant do, it's only relivant if you're going 10/10's.

that makes sense yet at the same time if your ultimate front grip went up and not your rear that would decrease undeersteer bias at the limit not increase

 

FWIW or to confuse matters.....

27 Front / Stock rear bar on my STi..... best bang for the buck period on my 05 STi was the big front bar on the stock suspension.

But my STi seems to be a freak and lifts the rear wheel in any tight corner on anything but the stock bar. Believe me, I went through 3 different rear sways before ending up back at the stock one.

 

Hi Guys,

The idea of sway bars it to keep the car as flat as possible and as much contact patch of all four tyres on the road.Also keeping the car flat will stop from riding the outside of the tyre and having it roll under which causes loss of grip.
Usually with softer springs like say OE the use of a larger sway bar will stop the roll and the sofetr spring will still give the comfort and take up the bumps in the road surface .
On the average it is best to have one or the other whe street car with the odd track day and that is larger bar with soft spring and not as large with say coilovers or firmer spring as the springs are allready helping the roll and with large of both will leave very high spring loads when in a corner and if you hit bumps in that corner can cause skip without it being dampered to suite and most off the shelf shocks or cheaper coil overs will not have that.

There ios so much can be explained but in basics it is to keep as much contact patch of tyre on the road at all times as in the end this is where grip is achieved.

The Question of why a larger front will cause understeer so why would you upgrade the rear as well is that just the front will induce more understeer than cars are allready designed to have from factory as the rear will pitch and cause the outside front tyre to ride on the outer edge and roll under causing less contact on the road henve less grip.
If the sway bars are paired and the car stays faltter with tehm balanced between understeer and oversteer you will achieve the best grip available