Rear or Front sway bar a better mod?

[A1337STI]

So after hearing the word out on the street is you can upgrade either your front OR your rear sway bar now in stock.


Which one will make a subaru faster out there at autocross?

anyone stumble upon any actual testing out there on the internets ?

[sperry]

People used to go with the biggest front bar possible back when only the front bar was allowed in Stock. The idea was that if the front bar was super stiff, it would prevent roll on the front axle, which would prevent positive dynamic camber, which would ultimately lead to more grip.

A still front bar is generally counter-productive to improving front end grip. This was a special situation specifically related to autocross and the fact you weren't allowed to change the rear bar. Normal logic would say that a very soft front bar would improve handling by making the rear relatively stiffer.

So, I can't say with any certainty, but IMO I would expect that going to a massive rear bar and leaving the front stock would be better. Sure, the stock front dynamic camber will still suck, but at least the rear will rotate anyway. Ideally, you'd go very stiff on both ends (but stiffer in the rear), but that's not allowed.

When the new "Street" rules replace Stock, and you'll be allowed camber devices + 1 bar, the obvious answer will be "add a bunch of negative camber to the front axle, install a big rear bar". So, in prep for next year's rules... go with the rear bar.

[MattR]

I went with a massive new bar in the rear on the mini and it has worked out well so far

[Dean]

If it was a dedicated autocross car, i would stick to a large front bar to eliminate the positive camber effect and toe out in the rear to get it to rotate.

[AtomicLabMonkey]

Stiffer rear bar.

[A1337STI]

Wow i totally love the new rules, though i may need to find a stock cat back...

Ill have to go rear sway shopping this year.

[sperry]

Originally Posted by Dean

If it was a dedicated autocross car, i would stick to a large front bar to eliminate the positive camber effect and toe out in the rear to get it to rotate.

A stiffer rear bar probably still handles better/goes faster.

It doesn't really matter if you get ultimate traction at autocross in an sti since you can always make up for it by nailing the throttle earlier. As long as you can get the car rotated to point at the exit, as soon as you hit the gas the nose lifts and all the camber issues go away.

[A1337STI]

Sounds like i should definitely order an adjustable rear sway and just try it out one weekend.. (i still have my stock front ... somewhere ...)

i'm not sure if i still have the stock front bushings.. but i think those are really cheap on rock auto . and then i'm all set for "street" class next year... win win!



speaking of which... does anyone have an ajustable RSB sitting in their garage that they want to sell?

[SoyKraut]

I have a 22 mm adjustable Perrin bar off my 02 WRX sitting around in my garage. Still has all the brackets and other bits attached. Might fit? You are welcome to try!

[A1337STI]

Ide love to give that a try. :-)

[cody]

Should fit, I think! You might need to go bigger though...depends on your alignment and driving style.

[A1337STI]

i was thinking of buying the eibach 25 mm sway bar kit (front and rear) and using just the rear, and putting an upgraded front back on for next year (new class rules) the rear is adjustable on the kit...

but i can certainly try out a 22 mm rear... might not be enough of a bump over stock to be faster than using a 27 mm front...

hmmmmm... :O

my alignment is very limited... i've got a hair more neg camber than stock up front, rear is not adjustable.
-.75 or -.5 up front (depending on who's rack) -1.75 in the rear
1/8 toe out front, 0 toe rear...

car felt faster with rear toe out, but the tire wear is pretty bad...

[SoyKraut]

Don't know how big the stock STI rear bar is. But, the 22 mm bar made a noticeable difference in how much the car rotates. Particularly when set on full stiff in my WRX. If you really want the car to rotate, get a Whiteline 27mm rear bar or a Hotchkiss Autocross bar for the rear and run a small bar from a lesser Impreza model in the front. Lift off when going fast = going around!

If you want to meet somewhere this weekend to pick up the Perrin bar to try out just let me know. Actually, some of the Kspeed guys are meeting up tonight at Ceol. I could bring it there!

[A1337STI]

stock STI has a 20 front and 20 rear...

i believe the wrx has a 17 mm stock rear? and i'm not sure how big the stock front is.. i know my 93 GC (FWD) had a stock 17 mm front, and the rs 2.5 had a 18 front and 13 rear... or i should say I **think**

so i would fathom a stock wrx is something like 18 front 17 rear, or 20 front 17 rear...


Still i definitely want to give it a try. thanks

[cody]

It varied. Mine was 20 front, 17 rear so my first mod was a "sedan" OEM 20mm rear bar and solid endlinks, which was perfect for a first step for me. Then I went 22mm adjustable rear (and eventually front too) which worked well too.

Alignment makes a big difference. With your alignment, I'd say 22mm rear won't be enough, but you do have the fancy diffs (front LSD and DCCD center) so maybe that will help you get more throttle oversteer. Definitely give it a try, because driving style and what your used to will affect it, but I bet a 25-28mm rear bar would be better for autox in your car.

[A1337STI]

ya i was thinking i could combat the wheel lift with using some center lock ... and at least there's a clutch pack in the rear, but its down to 11 ft pounds of break away ..

Aaron was super awesome and hooked me up with his... we think a 22 ? but he cut off the 22 hole so its a 23-24 now.. I'm wondering if my stock spring rates will be enough to keep the wheels down even set to 23 .. only 1 way to find out...

Jeana and I are both used to a more tail happy setup from rallyx , although pavement driving is a lot different. i suspect a lot of spins in our future..

I've been consistently behind matt by about 1.3 seconds , and just barely ahead of Nick in class .. so i should be able to tell if its a better or worse setup.

I think Dean's idea of the big front sway and rear toe out would probably be the fastest .. just don't know if i want to go through that much tire wear .. esp with 2 drivers

[cody]

That's cool. FWIW, I never use the "full soft" holes on mine anyway. The only time it would be an advantage is off road or in the snow, and then you might as well just disconnect them entirely. I don't imagine you'll want anything other than the "full stiff" setting for autox in your car.

I wouldn't worry too much about rear wheel lift since it only occurs when you're completely off the gas. Inside front wheelspin was always my issue and I nearly beat it with better damping and fatter tires, then just being more judicious with the gas in 1st gear exiting a tight corner did the rest. Going with a thicker front bar also seemed to help, though it should have made it worse, in theory. Anyway, you have a front LSD.

[A1337STI]

what are your spring rates.. and good point, lifting a rear inside under decel (or even coasting) won't be bad..

and could add a lot to the fun factor (if it loosens up the back end)

[cody]

Originally Posted by A1337STI

what are your spring rates.. and good point, lifting a rear inside under decel (or even coasting) won't be bad..

and could add a lot to the fun factor (if it loosens up the back end)

Crucial Racing is long gone, but I found the spring rates in the following post.

Specifications:

Spring rate front: 257 lb/in

Spring rate rear: 217 lb/in

Drop front: 1.25" on WRX, 12.5 mm on STi

Drop Rear: 0.9" on WRX, 9.0 mm on STi.


These are the same high performance spring rates as the highly-lauded and thoroughly-tested JDM STi "Pinks," but the Crucial springs have better materials quality, smoother progressive rates (plus are progressive both front and rear, while the JDM Pinks are only progressive on the rear, and linear front), offer slightly more drop up front for a nicer, more even stance (JDM Pinks are 1.0" both front and rear on WRX, 10mm front/rear on STi), actually come with a warranty, cost significantly less, and aren't pink. Our customers who have switched from Pinks to our springs all said that ours ride much, much smoother while simultaneously handling better with quicker response, more grip, and better control. You can't go wrong.

Wagon Owners -- these are GREAT springs for you, too! The combination of our quite stiff rates and our conservative drops means absolutely positively NO 'saggy butt' disorder that is common with many aftermarket springs made specifically with the sedan in mind. Ours lack nothing whatsoever over those 'wagon specific' springs, except for the generally wimpy spring rates offered. We know wagon owners drive hard and track their cars also! The Crucial Sport Springs will outperform those others in every category, from performance to ride to looks. By focusing on performance first and keeping our drop mild, we have created a set of springs that truly performs to their maximum potential on both sedans and wagons.

Lifetime warranty? Of course!

Fitment – MY 04-06 WRX and WRX/STi, sedan and wagon, plus Saab 9-2x. Also fits 02/03 Impreza perfectly with the use of '04+ rear top hats. Will work on Forester.

All Crucial Racing Systems parts are intended for off-road use only. Professional install recommended.

Manufactured in Germany, our Sport Springs are ISO 9001 and TÜV approved - the world’s highest quality standard for automotive suspension components. These progressive rate springs are cold rolled using special oil tempered spring steels of high tensile strength chrome-silicon (CrSi) and chrome-silicon-vanadium (CrSiV) alloys to reduce spring weight to optimize handling and response while maintaining high material strength. Finally, the springs are phosphated and powder coated jet black to ensure a superior corrosion barrier for years of service.

These are easily some of the highest quality, best performing springs available for your Subaru anywhere! Of all of our products, our sport springs have probably received the most consistently glowingly positive reviews from our customers. You will love them, too!

http://www.i-club.com/forums/suspens...talled-150421/

[A1337STI]

cool. so just slightly stiffer than an STI ... so aprox the same sways should work for me using 255 tires (i seem to recall you use 245s )

[cody]

I run 255s now too, but they're crappy Nitto NT05s that came on the Volks I bought. They aren't as sticky as Starspecs but run wide too and were good enough for me to still get first in my class last year, here in SR.

Our cars are very different but a lot of the differences cancel each other out (like I have a better alignment but worse weight distribution) so it's not a terrible comparison.