Well guys, I have intended to put a few FAQ threads together to help everyone with some basic suspension upgrades. This shall be be the first of these.
Intentions of this post:
This swaybar and endlink FAQ will explain the basics of how swaybars work (what function they have in your vehicle's suspension) and the effects of changing them can/will have on the handling of your vehicle.
Note: This information is gathered from my personal experience with different swaybar setups on both street and AutoX and from the experience of others on this forum and other forums. It is intended only to used as a guide. You as the end user are ultimately responsible to understand the handling of your vehicle and the effects of any changes that you make. Please research all of your modifications carefully and select the modifications that you are ultimately comfortable in installing on your vehicle.
What do swaybars do?
Swaybars (anti roll bars, stabilizer bars, etc.) limit the amount of body roll your vehicle will exhibit while cornering by increasing the roll stiffness of the suspension. The swaybar is attached to the suspension arms to limit the independent movement of these arms.
As the body of the vehicle rolls into a corner the loaded suspension arm (outside wheel) will apply an upward vertical force into the swaybar while the spring of the opposite (unloaded) side will apply a downward vertical force. These opposing forces create a torsional deflection in the swaybar. A larger swaybar is better able to resist this torsional deflection and therefore will transmit more of the force from the unloaded spring into the loaded tire limiting the amount the body is allowed to roll. The stiffness of your springs will directly affect the effectiveness of your swaybars.
Please read for more info: http://en.wikipedia.org/wiki/Sway_bar
How does a larger front swaybar affect performance and will it cause understeer?
First point: Body roll is caused by weight transfer.
Second point: A tire's grip is created by:
a) The coefficient of friction between the tire and the surface it is in contact with. (These for the intent of our discussion are constant)
b) The normal force applied to the tire's contact patch. (ie. weight transfer)
Third point: The WRX uses a MacPherson strut style front suspension. This suspension design, due to the upper suspension mounting point being the top of the strut assy. located at the top of the strut tower, suffers quite a bit of camber loss due to body roll in corners. A larger front swaybar will limit this camber loss to allow the tire to maintain its contact area in the corner. This increase in available contact area outweighs the loss in weight transfer (less body roll) to that tire.
So, the answer is both yes and no.
Yes - The increase in roll stiffness will limit the camber loss experienced during cornering, thereby allowing the tire to maintain a useful contact patch, provide more grip and ultimately reduce understeer.
No - To much roll stiffness will not allow enough weight to transfer to the tire and the car will understeer.
There is a fine line to this and the ultimate answer rests on a number of variables such as:
a) The type of driving you do. (ie. Street, AutoX or Track)
b) The overall roll stiffness provided by both the springs and the swaybars.
c) The roll stiffness of the rear end of the vehicle, such as the tendency to oversteer.
How does a larger rear swaybar affect performance and will it cause oversteer?
Short answer: Yes, on a WRX a larger rear swaybar will cause oversteer. The larger rear swaybar accomplishes this by increasing the roll stiffness and reducing the weight transfer to the tire reducing grip. The level of oversteer experienced can range from making the handling more neutral and balanced to outright snap oversteer. It is all based on the levels of front grip and the balance to the rear grip.
However to contradict myself, if you are running rear camber (approx. -1.0 or less) a softer rear swaybar will allow more body roll and this will result in a decrease in camber reducing the contact patch of the tire. This reduced contact patch will lessen the tire's grip and can cause oversteer.
What are the difference in solid vs. hollow swaybars?
Weight & price. Seriously.
A hollow swaybar can be manufactured to be just as stiff as a solid swaybar, it is just more costly to do so. Tube/pipe is just simply more expensive than bar. Tube/pipe is also only available in limited sizes, therefore it does not provide as many options to the designer.
The only benefit of a hollow swaybar is the weight savings, all else being equal.
Whiteline technical article.
Who makes the "best" swaybar?
A swaybar is a swaybar. It is simply a bent piece of steel bar with some holes at the end. The only real requirement is that it fits. Most major manufacturers do not have any fitment problems at this point.
I will not list manufacturers as I do not want to favor any manufactures/vendors. Please search the threads and/or PM our vendors to find info on the manufactures and pricing. I'll say it again, please support our vendors, they ultimately keep this site running.