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Old 09-17-2004, 03:08 PM   #1
Rich10
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Default Autocross: faster with a stiffer front swaybar?

My current setup is Eibach springs, a Cusco rear swaybar, Whiteline HD endlinks, and a custom alignment with -1 degree of camber up front. Would I be faster with a stiffer front swaybar?

If you have put on a stiffer front swaybar, I'd like to hear your observations.
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Old 09-17-2004, 03:15 PM   #2
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Camber plates will be faster than a FSB.

I think without additional camber up front, a stiffer swaybar will exaccerbate understeer.

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Old 09-17-2004, 03:41 PM   #3
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It will mostly with quick transitions such as slaloms. I would defintely recommend one. Shocks are going to help you too, as I see you've lowered the car on stock versions.
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Old 09-17-2004, 03:54 PM   #4
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I've read all over this site that WRX's don't follow the normal rules for suspension set-up, the really fast guys are stiffening the front to LESSEN understeer. Although this is opposite the traditional rules, it's not an uncommon situation when pushing stock suspension beyond what it's designed for (normal street driving). The specific reasons noted for stiffening the front to reduce understeer are:

1. Supposedly, front camber becomes more positive as the suspension compresses on WRXs. (This is highly unusual, most cars are designed to increase negative camber as suspension compresses.)
2. When turning the car hard, soft (OEM) suspension tends to run out of travel on the outside front wheel and bottom out on its bumpstop, resulting in a severe spike in spring rate (based on the spring rate of the bumpstops).

Other ways to address these problems are to run stiffer front springs and/or increase static negative camber (by installing camber plates). Unfortunately, both of these options are illegal if autocrossing in Stock class, hence the reason fast guys running in Stock class run stiff front sway bars. Other pros for going the swaybar route are cost and ease of installation, compared to camber plates or springs.
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Old 09-17-2004, 04:43 PM   #5
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Quote:
Originally Posted by quikSTi
1. (This is highly unusual, most cars are designed to increase negative camber as suspension compresses.)
Just about every modern car loses negative camber *relative to the ground* under compression. All cars also gain negative camber relative to the chassis under compression. MacPherson strut cars just lose a lot more camber under compression than others. Even Hondas with their awesome camber curves still lose camber relative to the ground, albeit a lot less than most cars, and still benefit from a stiffer front swaybar to lessen body roll and thus camber loss ASSUMING springs can't be changed, like in a stock class.

A front swaybar is a good way to get rid of some roll without sacrificing as much ride quality as you would with stiff springs. I'd suggest at least -2.5 degrees of static front camber before you change anything else.
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Old 09-17-2004, 04:52 PM   #6
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Quote:
Originally Posted by TeamSlowdotOrg
Just about every modern car loses negative camber *relative to the ground* under compression. All cars also gain negative camber relative to the chassis under compression. MacPherson strut cars just lose a lot more camber under compression than others.
Okay, I think I'm with you. In my post above, I was referring only to the effect of compression on the suspension geometry and failing to include the effect of "body roll" (sway). If I'm connecting the dots correctly, even though the suspension is gaining negative camber under compression, "body roll" (sway) has the opposite effect, which offsets those gains and then some, resulting in an overall loss of negative camber relative to the ground. Correct?

Last edited by quikSTi; 09-17-2004 at 04:57 PM.
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Old 09-17-2004, 07:18 PM   #7
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Correctomundo.
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Old 09-17-2004, 10:34 PM   #8
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I will probably be running a stiffer sway bar next year in DS to try it out. It should make me faster as there will be less dynamic camber loss and quicker transitions. You could argue that adding a FSB takes weight off the front outside tire which in turn decreases grip but correcting the deflection in the suspension geometry at such extremes I believe will offer greater benfits. As far as inducing more understeer, most people probably slap one on thinking their car will handle like a mini now and overdrive the car.
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Old 09-18-2004, 12:37 AM   #9
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Quote:
Originally Posted by quikSTi

1. Supposedly, front camber becomes more positive as the suspension compresses on WRXs. (This is highly unusual, most cars are designed to increase negative camber as suspension compresses.)
And just in case you want a visual this car has -3.25 degrees of static negative camber but looked like this when it turned


Makofoto has since fixed the problem which was from too low of spring rates but they are good pics to show what happens on with mac struts and body roll.
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Old 09-18-2004, 04:01 AM   #10
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Embarrassing to see those old photos! ... but they are instructive!

I've now got Tein Flex's with 450/550 springs ... together with a 1" Hotchkis Sway bars/Poltec Endlinks ... and also stiffer bushings all around, STI trailing arms, adjustable lateral links, SubFrame bolts. On a smooth track I usually have the front damper on 8 out of 16 ... the rear is set full stiff. I actually recently reduced my front camber from about 3.25 to 3.0 ... Zero toe all around. 1.4 camber in the rear.

Car HANDLES sweet ... and is FAST!

Fastest Suby out of 30, including 7 STI's plus 6 Evo's at last months local AX - including a STI driven by a 1 lap of American driver, an EVO MR driven by two Track magazine test drivers, and a EVO8 driven by a new lady's National Champion.

The Wagon now, outside front wheel upright, inside wheel shows "static" neg. camber:

Last edited by makofoto; 09-18-2004 at 04:27 AM.
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Old 09-18-2004, 04:02 AM   #11
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Good Front Sway Bar Test Article: http://www.selgp.com/sti_modifications.htm
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Old 09-18-2004, 04:21 AM   #12
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I much preferred my WRX with the smaller (19mm) front bar, just seemed easier to keep the front tucked in, though to be fair I'd never run the 19mm with R compounds, only street tires.

Tom, KC, how about you guys put your $0.02 in?
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Old 09-18-2004, 04:25 AM   #13
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In case they don't chime in ... I believe at least one of them is running a BIG 26 mm Whiteline Front Sway Bar ...
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Old 09-18-2004, 11:51 AM   #14
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Quote:
Originally Posted by makofoto
In case they don't chime in ... I believe at least one of them is running a BIG 26 mm Whiteline Front Sway Bar ...
And of course the question was for SM, so he could be running a honking big rear bar.... and of course what springs you have also make a difference.
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Old 09-18-2004, 07:16 PM   #15
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Stx ...
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Old 09-19-2004, 10:52 PM   #16
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I'm keeping my 04 STI strictly A Stock and installed the Cobb 22cm frnt ARB and it has balanced the car beautifully! The debilitating understeer is gone and I can actually dial in a little oversteer with (street) tire pressures.
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Old 09-20-2004, 12:17 PM   #17
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The fast A-Stock guys are running bigger front bars. I haven't seen a case on a Subaru where the larger front bar didn't increase grip.

Case in point: My own car, with 450# springs up front and 550# springs in the rear, along with a 22mm rear swaybar. I went from a 21mm swaybar up front to a 24mm up front and gained grip. Note that I have camber plates, and I not only gained grip with full negative camber, but also gained grip on my street setting, which had far less static camber.

I am absolutely convinced between my results, Tom's results, Miranda's results, and SELGP's results that a larger front bar is absolutely crucial. (I just watched the SELGP guys drive really well at the Subaru Challenge in MD; they obviously know what they're doing.)

Faster transitions (crucial in autox!) along with more front grip...why would you not want a larger front bar?
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Old 09-23-2004, 09:58 AM   #18
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Bump. Anyone else try this?
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Old 09-23-2004, 10:40 AM   #19
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I've had great success with large front sway bars on all the project vehicles that I've built.

I currently have a customer running a custom JIC-based suspension setup of my own concoction on a stock power STi, with a Whiteline 24mm solid front bar and a matching adjustable rear bar set to 24, and he's currently lapping Road Atlanta at 1:39.xx. He turned 1:40.15 on stock tires with this setup!

There's magic in a large front sway bar, and it is good.
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Old 09-23-2004, 01:38 PM   #20
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Is there a reason you only have 1 degree of negative camber? Personally, that's the first thing I'd look at fixing. Worry about a FSB afterward.
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Old 09-23-2004, 01:58 PM   #21
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Quote:
Originally Posted by jcroy66
Is there a reason you only have 1 degree of negative camber? Personally, that's the first thing I'd look at fixing. Worry about a FSB afterward.
The front sway will help his camber issues if he is limited at -1 for some particular reason. It won't magically give him more, but it will help minimize the detrimental effects of body roll.
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Old 09-23-2004, 02:11 PM   #22
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I'm going to go out on a limb here and tell you that I personally do not like a large front swaybar.

I would agree with Jen that more negative camber up front would give you more bang for the buck than the swaybar. Nobody is limited to -1 degree of camber, unless they are running in stock, which he obviously isn't.

Just my opinion.

Corey #89 STS
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Old 09-23-2004, 02:25 PM   #23
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Oh he's not truly limited; mentally limited. What I mean by that are excuses as to why someone can't run more negative camber, such as: "I don't want to use camber bolts and I don't like camber plates" or "I can't drive with that much camber on the street" or "I won't be able to stop," etc...the list goes on. That's what I meant by limited; I know his classification isn't limited since the rear bits and springs put him in STX or higher if there were mods he didn't disclose.
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Old 09-23-2004, 02:26 PM   #24
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If you have the option to do it with springs and camber plates... do it with springs and camber plates. In autocross... I would really only recomend the large FSB for specific situations... not as a rule of thumb. Example would be the camber limited stock classes where you can't change much of anything and have limited adjustment ranges.

If (when) I leave A-Stock... the first thing I'll do is ditch the front bar.

-Matt
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Old 09-23-2004, 02:27 PM   #25
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Quote:
Originally Posted by Corey
I'm going to go out on a limb here and tell you that I personally do not like a large front swaybar.
Please explain. Did a stiffer front bar result in some specific handling problem(s) and/or slower lap times in autocross? "Inquiring minds want to know."
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