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Discussion Starter · #1 ·
Anybody know of any articles on swaybars and why/how they are sized to cars? It seems common knowledge that they reduce body roll by transferring forces from the loaded side to the opposite side. Also that increasing the rear bar decreases understeer, but increasing the front bar increases understeer.

I'm wondering how the auto manufacturers determine what sizes to use on cars. Shouldn't a heavier car have thicker sway bars? Does f/r weight balance and drive wheels affect the size difference between f/r bars?

An Integra Type-R has 24 mm front and 22 mm rear bars v. the WRX's 20/20 mm f/r sway bars. WRXs are 400-500 pounds heavier than the Integra, yet have smaller sway bars. All G3 Integras have 2 mm larger front sway bars than the much heavier WRX, however, the weight balance is 62/38 v. 60/40 and FWD v. AWD.

People say that sway bars have a much bigger effect on body roll than springs & shocks. Is this true? The G3 GS-R seemed to roll like a pig when they softened the springs from the G2 Integra (correct me if I'm wrong, but I don't think they changed the sway bars). Do you need stiffer springs (and shocks?) if you increase the sway bar size?
 

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Please see the Tech Reference sticky for a suspension setup chart and a swaybar size comparison chart.

Swaybar size depends on a lot of factors including car weight, spring rates, suspension geometry, drivetrain, weight balance, etc. etc. etc. I don't think we have any members with the knowledge to adequately compare one car to another.

Springs have a huge effect on body roll, as well as many other suspension atributes. Swaybars only have control over body roll, but can effect handling balance as well.

Please remember that a lack of body roll does not simply equal better handling. The car would not handle correctly with zero body roll.

Big swaybars are a way to reduce body roll cheaply but are not perfect. Significantly, they remove a degree of independence for the suspension, resulting in worse handling over rough surfaces and in low-grip situations. It is interesting to note that the STi RA (SPT Sedan) setup actually reduces the size of the front swaybar while leaving the rear alone. It is also interesting that rally teams tend to run small swaybars or none at all so that the suspension can work fully independently. (as a side note, most companies that advertise "fully independent suspension" are not being entirely truthful as most run swaybars.

Right now I'm running 24mm on my Whiteline adjustable rear swaybar. I found the 22mm front bar to be a step in the wrong direction and removed it. I will be upgrading to STi springs in the near future combined with an adjustable strut. At that time I will also install the 19mm STi front bar (20mm stock) and will bump the Whiteline down to 20 or 21 mm and rely on my new springs and struts for adjusting the balance of the chassis. That way I let the suspension work fully in the way that it should.

Chris
 

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Discussion Starter · #3 ·
Yeah, I looked at the Si tweak chart.

My biggest problem is the excessive body roll I feel in the wagon (compared to other cars I've owned - haven't yet rode in the sedan!). I'm wondering if it's because of the soft springs or smaller rear sway bar or both combined with the heavier weight. In driving to Winter Park, going around the hairpin curves at slower speeds, I felt less confident than in my old stock '90 CRX si although high speed curves feel more stable. I don't like the feeling of tipping over. :eek: I'd rather have the wheels loose grip than the tipsy feeling of rolling. Most people recommend replacing the rear sway bar with the sedan's or bigger. In researching sizes, I came to comparing with the Integra. I'm not concerned so much with handling on rough surfaces as with the street. This is my daily driver. I don't plan on rallying or auto-x (that could change if I don't get a job soon and have to sell the Type-R). On rough surfaces or poor environmental conditions, I simply slow down and don't push as hard. I like the fact that the car has compliance for potholes and speedbumps, but wouldn't mind giving in to a slightly harsher ride for better handling.
 
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