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After market sway bars......rule of thumb?


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#1 DCVR

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Posted 14 August 2012 - 7:03 PM

It's prolly one of the first, easiest, and best bang for buck mods we all do to the old girls to stiffen up the handling.

To reduce understeer........I always thought the rule of thumb was fatter bar at the back and smaller dai at the front?

But I have also seen fatter bars on the front........or equal dai bars on the front............. so what's the go?
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#2 boostin

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Posted 14 August 2012 - 7:24 PM

Completely different suspension system, but my BL has 24mm front bar and 20mm rear, and not a hint of understeer. I guess I'll find out for certain on the track!
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#3 DCVR

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Posted 14 August 2012 - 7:30 PM

Completely different suspension system, but my BL has 24mm front bar and 20mm rear, and not a hint of understeer. I guess I'll find out for certain on the track!


yep that's exactly what I'm talking about..........strange, but if you've got no understeer that's awesome. So ur gona track the beast?...nice
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#4 DacerX

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Posted 14 August 2012 - 8:28 PM

I've got 22 on the front and 20 on the back both solid and adjustable and I have no understeer ethier I have mine set to soft as we as I don't push it really hard just yet
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#5 DCVR

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Posted 14 August 2012 - 8:53 PM

Well well........this is all very interesting. It seems my rule of thumb is just a myth!

I have a 3 way adjustable 20 on the rear and a factory V3sti on the front and yep I get a bit of understeer on the roads most noticeably in the wet in corners. Scares the shit outta me!. I've got a a hollow non adjustable 24 to go on the front........I'll try that.

Hollow 24 (according to Uncle Google) has about same torsional strength as solid 22.

Interesting read on the solid Vs hollow sway bars
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#6 DacerX

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Posted 14 August 2012 - 10:01 PM

I used to have hollow 24 on front and rear of my bc
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#7 Familyman

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Posted 14 August 2012 - 11:24 PM

Was told by my tame mechanic who use to indulge in quite a bit of competitive track work that matching bars for front and rear were the most neutral solution.

If you have a rear bar larger than your front and still get understeer, is it possible that something else is causing it? Flex in steering rack? Front swaybar links maybe weaker than rear? Just throwing out wild ideas here.
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#8 boostin

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Posted 15 August 2012 - 12:08 AM


Completely different suspension system, but my BL has 24mm front bar and 20mm rear, and not a hint of understeer. I guess I'll find out for certain on the track!


yep that's exactly what I'm talking about..........strange, but if you've got no understeer that's awesome. So ur gona track the beast?...nice


Yep, doing Ray's Taupo track day.

I had matching 20mm bars in the wagon, and that would oversteer when pushed. Not a snap though, was nice and progressive.
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#9 DCVR

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Posted 15 August 2012 - 1:36 AM

Was told by my tame mechanic who use to indulge in quite a bit of competitive track work that matching bars for front and rear were the most neutral solution.

If you have a rear bar larger than your front and still get understeer, is it possible that something else is causing it? Flex in steering rack? Front swaybar links maybe weaker than rear? Just throwing out wild ideas here.


It's all possible...........i will experiment with the setup when I get it on the road. I'll whack the front hollow in for now and road test later
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#10 Ichi Ban

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Posted 15 August 2012 - 5:33 AM

Many factors come into play with under/oversteer

Driver being the main one

Tuning the suspension to suit one driver often wont suit another

Bars, tyres, pressures, alignment, shock and spring rates, brake bias (different pads/rotors/calipers all effect this), driving style, and DCCD setting all come into play

The sub 1.20 Subaru's at manfeild that i have dealt with, went better with the OEM front bar than they did with an aftermarket bar

#11 chasey89

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Posted 15 August 2012 - 11:15 PM



Completely different suspension system, but my BL has 24mm front bar and 20mm rear, and not a hint of understeer. I guess I'll find out for certain on the track!


yep that's exactly what I'm talking about..........strange, but if you've got no understeer that's awesome. So ur gona track the beast?...nice


Yep, doing Ray's Taupo track day.

I had matching 20mm bars in the wagon, and that would oversteer when pushed. Not a snap though, was nice and progressive.



I can support that comment 100%, with the bars in the wagon it will step out if you want it to and push it, but can still throw it into a corner knowing its not going to just cut loose on you.

I was never big on sway bars until I went from my wagon to this one. What a difference.

#12 boostin

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Posted 16 August 2012 - 12:06 AM

Lol I need to take you for a spin in the BL. Body roll is pretty much eliminated with the 24mm front bar! I'm often rocking on 2 wheels going in and out of driveways on an angle.
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#13 DacerX

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Posted 16 August 2012 - 12:45 AM

Is it a hollow bar boostin ?
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#14 boostin

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Posted 16 August 2012 - 1:31 AM

Going by the weight of it, no.
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#15 chasey89

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Posted 16 August 2012 - 1:34 AM

Lol I need to take you for a spin in the BL. Body roll is pretty much eliminated with the 24mm front bar! I'm often rocking on 2 wheels going in and out of driveways on an angle.



hahaha! NOICE~~!!~~ would love to experience that beast of a machine!! 2 wheels pulling in and out of driveways! Love it!

#16 Reuben

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Posted 16 August 2012 - 4:59 AM

I gotta say, there's many ways to reduce understeer.

One of the biggest for me, and what essentially killed any last bits of understeer my wagon had on the road, was the K-brace. Getting rid of the subframe flex REALLY helps in the slow speed stuff, like hairpins. I found the sway bars (went from 20mm stock to 22mm cusco, front and rear) Helped more in the high speed stuff, didn't notice a change in under or oversteer characteristics (expected, didn't change any bias), but just overall much higher grip on fast sweepers and such. He still will oversteer on the sweepers if you push him though, arse is always first to come out on that car, but very very progressively (Big ol wagon, with bung GDB STi rear shocks, woohoo!).
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#17 madmike

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Posted 16 August 2012 - 8:11 AM

best thing to get rid of understeer is a big dose of handbrake.....

Backing the bitch in FTW...
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#18 DCVR

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Posted 16 August 2012 - 10:00 PM

Lol.....
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#19 MercuryFree

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Posted 10 September 2012 - 3:18 AM

It's not HAVING a bigger rear bar than front that's a rule of thumb, it's that to improve understeer characteristics, INCREASING the size of the rear bar will generally work. Same with increasing the size of the front to reduce oversteer.

But as ichi said, many factors. Need to get mine back out on track to see if my bigger rear swaybar will actually improve my laptimes. Feels better but feel doesn't always equal results
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#20 RS-YES

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Posted 10 September 2012 - 11:28 PM

When re-fitting sway bars do you have to torque to factory specs or just tighten the F outta of it?




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