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Old 09-23-2004, 02:45 PM   #26
quikSTi
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Quote:
Originally Posted by Porter
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.
Okay, I'll bite.
The approach described above opposes conventional wisdom and begs the question:
Why did you/he choose bigger bars, which decrease left/right independence of the suspension, when you could have achieved the same benefits and retained more independence by using stiffer springs w/ the custom JIC suspension?
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Old 09-23-2004, 02:49 PM   #27
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um, this is an interesting find. Stiffer front swaybar fix the understeering and provides more grip? I am not doubting since many of you tried it personaly. However, how does it compare to those who only used the thicker rear swaybar to fix the understeering?

Also for using the thicker front swaybar, is it subjected to the use of stock spring? Coilover? or any other aftermarket springs?
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Old 09-23-2004, 02:54 PM   #28
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Old 09-23-2004, 03:08 PM   #29
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A larger rear sway bar will increase oversteer *while braking*.

A larger front sway bar will increase oversteer *while accelerating*.


And quikSTi, this is not a conventional car. Conventional wisdom does not apply. What works on a Miata does not work on a Subaru. If you want to discuss more, call me on the phone sometime...

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Old 09-23-2004, 03:10 PM   #30
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Quote:
Originally Posted by quikSTi
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."
I like it if the car feels like it has alot of "bite" at corner entry. I feel that the FSB takes the "bite feeling" away from the front and almost makes it feel too stiff. It just doesn't agree with my driving style.

Like I said, it's just my opinion. Others do quite well with a big FSB. I don't run one.

Corey #89 STS

Last edited by Corey; 09-23-2004 at 03:19 PM.
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Old 09-23-2004, 03:15 PM   #31
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Quote:
Originally Posted by quikSTi
Okay, I'll bite.
The approach described above opposes conventional wisdom and begs the question:
Why did you/he choose bigger bars, which decrease left/right independence of the suspension, when you could have achieved the same benefits and retained more independence by using stiffer springs w/ the custom JIC suspension?
Funny you should mention that. I have a custom set of JICs with 450# (8k) springs in the front and 550# (10k) springs in the back. I went from a 21mm to a 24mm front bar and increased grip even with those spring rates. Did I sacrifice some suspension independance? Perhaps; in terms of paper-racing it certainly looks like I did. In practical application though, if I'm missing it I can't tell because I'm faster overall. Suspension independance is only important to a point.

Look at photos of Mike King's car during the ProSolo Finale the photos show still very notable amounts of body roll and if I don't miss my guess, he was on 7k springs (~400lbs) in the front. (He used to be at 7k/9k, not sure anymore.) It also looked like he had a large rear bar but not front bar due to his lifting the inside rear wheel so high.

I believe in bar balance; I don't want one significantly larger than the other. In addition to that, I also don't want bars that are too small for the rest of the suspension setup that I am running. Unless I were to go to silly high spring rates, I wouldn't be able to make my bars any smaller and still retain the grip, control, and transitional response that I require.
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Old 09-23-2004, 03:39 PM   #32
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Quote:
Originally Posted by DrBiggly
I have a custom set of JICs with 450# (8k) springs in the front and 550# (10k) springs in the back. I went from a 21mm to a 24mm front bar and increased grip even with those spring rates. Did I sacrifice some suspension independance? Perhaps; in terms of paper-racing it certainly looks like I did. In practical application though, if I'm missing it I can't tell because I'm faster overall.
Is this the set-up you had at the Rockingham autocross last month? If so, it didn't appear to be very grippy there. Is the improvement maybe more obvious on stickier surfaces?
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Old 09-23-2004, 03:42 PM   #33
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Quote:
Originally Posted by quikSTi
Is this the set-up you had at the Rockingham autocross last month? If so, it didn't appear to be very grippy there. Is the improvement maybe more obvious on stickier surfaces?
OW! Getting personal!
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Old 09-23-2004, 03:47 PM   #34
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Quote:
Originally Posted by Porter
OW! Getting personal!
Sorry if it came across that way, it honestly wasn't my intention.

Just trying to figure out which approaches really result in quantifiable handling improvements w/the STi, everyone seems to have conflicting opinions about what works.
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Old 09-23-2004, 03:51 PM   #35
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Quote:
Originally Posted by quikSTi
Is this the set-up you had at the Rockingham autocross last month? If so, it didn't appear to be very grippy there. Is the improvement maybe more obvious on stickier surfaces?
The tires, my infamiliarity with the car, and that surface all played a role. That surface did get better later on in the day however. That was my 2nd event in the car and I was (and still am) having trouble with some of my inputs. I ran my old tires (the 245/40/R17 Kumhos that I had at the Rockingham event) back to back with some 205/R16 Azenis and the Azenis were grippier even in that tiny size. Those Kumhos are now long gone and good riddance! They're not a lot of fun in transitions for sure. I think a new set is reasonably grippy only when hot, but otherwise I do not like them. That surface was also notably faster in the afternoon.

My times that day were dismal and I was very disappointed with my performance, again disappointed at the location, and the course design itself I did not feel comfortable with. Tom even ran poor times until he put on the cheater tires.

I also don't remember if I had fixed my ride height problems at that point or not; this made a nice difference in balance as in noob fashion, I had my coilovers all out of whack on ride height.

So really there were a lot of factors, not the least of which was me. On a personal note, I refuse to attend another event at that site as I believe it a very poor site.
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Old 09-23-2004, 03:52 PM   #36
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I can tell you is that it has made a quantifiable handling improvement in the cars that I've built, in terms of seconds per lap at Road Atlanta.

It depends on your approach to suspension tuning, though. Different driving styles will necessitate different approaches in terms of spring rate, sway bar sizing, etc.

I could write a book on this subject, and in fact have written mini-novellas on other forums on it, but my fingers are tired today.

Your mileage may vary. Go forth and experiment, brethren.
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Old 09-23-2004, 03:54 PM   #37
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Quote:
Originally Posted by quikSTi
Sorry if it came across that way, it honestly wasn't my intention.

Just trying to figure out which approaches really result in quantifiable handling improvements w/the STi, everyone seems to have conflicting opinions about what works.
Perhaps this will help?

http://www.selgp.com/sti_modifications.htm

I honestly wasn't so sure about these guys until I saw them run at the Subaru Challenge; now there is no doubt that they are indeed talented drivers.

Note: I didn't take it as a personal attack of any kind, merely an observation. I don't mind that you brought it up at all.
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Old 09-23-2004, 04:20 PM   #38
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I'm not talented nor am I competitive in AS - I ony get trophies because of lack of competition (it's usually myself and an older guy in a 993 Porsche who is just a tad slower than I am - which makes it fun but I digress :>) but I insstalled a Cobb 22cm FARB and it made a HUGE difference. It is correct that the Subies don't follow normal suspension laws and I couldn't believe how much understeer was ELIMINATED when I installed the bar. The car (04 STI) has a much sharper turn-in and corners as it on rails. The some tire pressure adjustments I've been able to dial in a little oversteer with makes late apexing a little easier. Best $150 I've spent on a car in a long time. Still doens't make me anywhere near as fast as the damn S2000's though. BS is really gonna suck next year.
Oh well...

"Racing is life. Everything before and after...is just waiting"
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Old 09-23-2004, 04:36 PM   #39
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Quote:
Originally Posted by DrBiggly
On a personal note, I refuse to attend another event at that site as I believe it a very poor site.
From what I've overheard, you're definitely not alone in that belief. It will be interesting to see if any autocrosses get scheduled for the Rockingham next season.
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Old 09-23-2004, 04:41 PM   #40
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I've got a similar question to the original poster. I've got STi V7 struts, STi Pink Springs(217#F,190#R), running -2.4 F, -1.1R camber, and I'm looking at getting sway bars to increase grip, transitional response, and dial in some more oversteer. I was originally thinking of a 21mm Front, 22mm adjustable rear bar, but now I'm thinking maybe 22F/24R would be better. Would the 22/24 combo be too stiff for my springs? Is a sway bar that big going to significantly affect my ride quality on the highway (I still have to make 5 hour road trips once a month in this car)?
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Old 09-23-2004, 04:47 PM   #41
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I'd try 24f and an adjustable rear set at 22mm before trying anything bigger.

I don't think the 22/24 combo that you suggested might be too stiff in the front, although in the rear it very well may be.
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Old 09-23-2004, 05:52 PM   #42
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Quote:
Originally Posted by fliz
I've got a similar question to the original poster. I've got STi V7 struts, STi Pink Springs(217#F,190#R), running -2.4 F, -1.1R camber, and I'm looking at getting sway bars to increase grip, transitional response, and dial in some more oversteer.
Since your ride height, spring rate, and camber are not stock configuration, the improvements stated about stiffer swaybars may not apply, and it's extremely difficult to predict whether or which of these sway bar combinations would be best or even an improvement over your current set-up. To get there, you need to first find out whether your current alignment and tire pressure settings are optimized. If you're trying to change the over/understeer tendencies of a car w/out first confirming your alignment and tire pressures are optimized within the adjustment range you have available, you're likely to achieve improved balance only at the expense of reduced grip, and the overall result is likely to be a faster feeling car that runs slower lap times.

Last edited by quikSTi; 09-23-2004 at 05:59 PM.
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Old 09-23-2004, 07:27 PM   #43
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Quote:
Originally Posted by quikSTi
Since your ride height, spring rate, and camber are not stock configuration, the improvements stated about stiffer swaybars may not apply, and it's extremely difficult to predict whether or which of these sway bar combinations would be best or even an improvement over your current set-up. To get there, you need to first find out whether your current alignment and tire pressure settings are optimized. If you're trying to change the over/understeer tendencies of a car w/out first confirming your alignment and tire pressures are optimized within the adjustment range you have available, you're likely to achieve improved balance only at the expense of reduced grip, and the overall result is likely to be a faster feeling car that runs slower lap times.
I have room for more negative adjustment in the rear, but up front I'm running as much camber as I can. I run 51 PSI up front, and have chalked that that is the lowest pressure that doesn't ride on the sidewall around corners (Toyo T1-S, 225/45/17). The front tires are still much warmer on the outside half of the tire, but it is better than with my old alignment (-1.2 front), which had only the outside 2" of the tire warming up during a run. I've tried running as low as 49 PSI up front, but the tires roll over, and then the outside edge is ALOT hotter than the rest of the tire.

The rear tires I've run from 46-48 PSI, and really don't notice much difference in the feel on course, or tire rollover.

Next year I will be running RE-070s, so I'm hoping I will be able to lower the pressures and improve grip also.

A recent pic of my car during cornering shows quite a bit of body roll, which I'm sure is killing my static negative camber, and I hope can be improved with a front sway. Since I'd like to maintain the balance I have on the car, I figured I would get a front and rear bar at the same time.

I figure a WRX on lowering springs with upgraded struts, running good neg. front camber wouldn't be all that uncommon, and others might have some info.
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Old 09-23-2004, 07:45 PM   #44
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Really I don't think you need front AND rear bars unless you have severe rotation problems.

Add front bar: More front grip and better rotation.
Add rear bar: Less rear grip and better rotation.

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Old 09-24-2004, 09:37 AM   #45
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With a stiffer front swaybar (21mm or 22mm), is there a need to upgrade the front endlinks? Taking a quick look under my car, the front endlinks seem to be solid (unlike the rear endlinks).

Also, is there a good writeup for the installation of a front swaybar?
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Old 09-24-2004, 10:02 AM   #46
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Quote:
Originally Posted by DrBiggly
My times that day were dismal and I was very disappointed with my performance, again disappointed at the location, and the course design itself I did not feel comfortable with. Tom even ran poor times until he put on the cheater tires.

I also don't remember if I had fixed my ride height problems at that point or not; this made a nice difference in balance as in noob fashion, I had my coilovers all out of whack on ride height.

So really there were a lot of factors, not the least of which was me. On a personal note, I refuse to attend another event at that site as I believe it a very poor site.
That was the same course they used for the divisional. Looking at the results from there, and our dry results... times are pretty much right where they should have been. http://www.phillyscca.com/Assets/res...NEDIV2004C.pdf

In the dry, Tom and I were running Low 39's/38's. Fastest STS time was low 39s (Corey) and same with fast STX (Both at the divisional results).

So... the course was driven the way it was supposed to be.

The only changes to the course were the laydown of extra pointer cones for the numer of novices we had and maybe one more element.... that was tightened on the Subaru course vs a little more open on the Divisional course.



--kC
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Old 09-24-2004, 10:03 AM   #47
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Quote:
Originally Posted by fliz
I have room for more negative adjustment in the rear, but up front I'm running as much camber as I can. I run 51 PSI up front, and have chalked that that is the lowest pressure that doesn't ride on the sidewall around corners (Toyo T1-S, 225/45/17). The front tires are still much warmer on the outside half of the tire, but it is better than with my old alignment (-1.2 front), which had only the outside 2" of the tire warming up during a run. I've tried running as low as 49 PSI up front, but the tires roll over, and then the outside edge is ALOT hotter than the rest of the tire.

The rear tires I've run from 46-48 PSI, and really don't notice much difference in the feel on course, or tire rollover.

Next year I will be running RE-070s, so I'm hoping I will be able to lower the pressures and improve grip also.

A recent pic of my car during cornering shows quite a bit of body roll, which I'm sure is killing my static negative camber, and I hope can be improved with a front sway. Since I'd like to maintain the balance I have on the car, I figured I would get a front and rear bar at the same time.

I figure a WRX on lowering springs with upgraded struts, running good neg. front camber wouldn't be all that uncommon, and others might have some info.
That seems like fairly high pressures in the front tires, especially for a 17 inch tire with short sidewalls. I've found that if your entry speed is too high in these WRX's, you are going to understeer like crazy. On a bone stock WRX wagon with 225/50/16 RA1's, I ran 38.5psi up front without tire rollover and no push. With 53psi in the rear, it gave me the perfect balance where I could get the back end to dance for me when needed. I might add that this setup would push too if I entered the corner too fast. The trick for me was to slow down to go faster...

Just my .02

Mike
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Old 09-24-2004, 10:04 AM   #48
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let me chime in....Please...A front Swaybar is a great addition for those driving styles that can use it....I also think...that a bigger front bar is a 'aquired taste' ...It makes sense in a FULL on TRACK but an Autocross situation I don't think it advantagous...( above 65 mph....)....My turnin on a Autocross course is very good...with 2.75 neg camber...when I added a front bigger bar....my turnin was not as crisp...Mid corner bite was enhanced by the bigger bar but resulted in a push condition exiting the turn.....On the Track...the Bigger bar helped the situation as you are carrying way more speed for the bar to be advantagous resulting in a Very smooth Transition upon exit allowing better accerlation off the corner...Me personally...I don't like a bigger front bar...so I agree with Corey on this one...It also depends on what compensation the Suspension is providing Ie: Valving, Rebound, dampning, and Spring Rates...So unless everyone is on the same suspension...its hard to justify the advantages and disadvantages of a Front bar.....

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Old 09-24-2004, 10:30 AM   #49
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Quote:
Originally Posted by KC
That was the same course they used for the divisional. Looking at the results from there, and our dry results... times are pretty much right where they should have been. http://www.phillyscca.com/Assets/res...NEDIV2004C.pdf

In the dry, Tom and I were running Low 39's/38's. Fastest STS time was low 39s (Corey) and same with fast STX (Both at the divisional results).

So... the course was driven the way it was supposed to be.

The only changes to the course were the laydown of extra pointer cones for the numer of novices we had and maybe one more element.... that was tightened on the Subaru course vs a little more open on the Divisional course.



--kC
(What's it gonna be for next year?)
KC,

I was referring back to the Rockingham event where someone above was asking me about a local event.

I didn't have any complaints with the course at the Subaru Challenge; in fact it was rather fun. According to the results, I was faster than you in the rain. Did you cone away a run or something? In the dry I ended up with a 39.45 something. My car ended up at a 38.9 for a fast time in the dry.
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Old 09-24-2004, 11:42 AM   #50
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Quote:
Originally Posted by quikSTi
Okay, I'll bite.
The approach described above opposes conventional wisdom and begs the question:
Why did you/he choose bigger bars, which decrease left/right independence of the suspension, when you could have achieved the same benefits and retained more independence by using stiffer springs w/ the custom JIC suspension?
I made this point a long time ago, the relationship between the two seems to be forgotten a lot.
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