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Which will best achieve my goals?

  • More negative front camber

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2004 fxt A/T
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Discussion Starter #1 (Edited)
Before any one makes the comment "Front swaybars will increase understeer", I know but it also increases front grip, better turn in, less positive camber increase, and more stability at speed.


I am putting in a STI steering rack and figured while I was in there why not replace the front swaybar at the same time. I also realize that the McPherson strut geometry imparts positive camber as the outside spring compresses. I am currently on OEM struts and springs with STI RSB and am simply not willing to give up ground clearance. I understand that lowering my COG will help more than either of these options, but I don't want a track car just a bit more stability while in the throttle and at the limit. So my question is, should I put in a 22mm front bar, adjust to more negative front camber, or a combination?
 

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Discussion Starter #3
How about bigger bar and more negative camber together?
I did put that as one of the poll options, and that is the one I am leaning towards since the car has to be re-aligned after the steering rack install.
 

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Not sure about the negative camber. But I was on WRX struts and STi RSBs. I put a 22/24mm FSB in the other day, and the difference was very nice! Better balance, response, and the car just felt better. It also seemed to increase my oversteer that was explained to me in another post.

I would go with a bigger FSB.
 

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I would suggest going ahead with the swaybar (since that's the most labor intensive and you'll be under there anyway!) and see how different it feels. After getting acclimated to that, then proceed to the camber adjustment. If you do both at the same time and do not like how it handles, then you are left wondering which change to make.

FWIW, I recently had my front camber adjusted and could tell a difference as far as immediate turn in. It's nice! :woohoo:
 

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2017 VW Golf SportWagen 5MT
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I'm with Doc, do the bar first then adjust the camber as needed. How much negative camber are we talking about here?

Stan
 

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I did put that as one of the poll options, and that is the one I am leaning towards since the car has to be re-aligned after the steering rack install.
Reading>Me

Doc's suggestion is best. Piece-by-piece evaluation will give you the best idea of what works and what doesn't for your driving style. Though with a 22mm I wouldn't really think that the results would be detrimental at all. It should give pretty neutral results, given the STI RSB size. Besides, if you go bigger than 22mm and you feel increased understeer, you could always opt for an adjustable 22-24mm RSB to fine tune some oversteer into the system.
 

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Discussion Starter #8
I'm with Doc, do the bar first then adjust the camber as needed. How much negative camber are we talking about here?

Stan
Not much -.5 to -1 degree, like stated if I were autox I would probably run -2.5 but I am just wanting a flatter tire patch while under load.
 

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Ol' Timer
2006 WRX Spec-C 6MT
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^^Yep. Larger bar (22mm) and start camber at -1. Since such little changes to camber will not decrease tire life so it's a win-win.

I would also highly suggest an adjustable bar and solid endlinks.
 

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Discussion Starter #13
Well it looks like that settles it, 22mm front sway and -1-1.5 degrees of front camber.

^^Yep. Larger bar (22mm) and start camber at -1. Since such little changes to camber will not decrease tire life so it's a win-win.

I would also highly suggest an adjustable bar and solid endlinks.
When I put in the STI RSB I went ahead and put KB endlinks in as well. I would like to get away with as little rear bar as possible to keep some articulation and get front grip sorted first. I wouldn't be apposed to an adjustable rear bar but maybe a rear strut tower bar here first. I just don't know how much larger bars all around will help with my tall soft sidewalls. Am I just being a pantie waste? Should I just stop thinking and get a rear swaybar as well to match the front? Thanks everyone for the recommendations.
 

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I just don't know how much larger bars all around will help with my tall soft sidewalls. Am I just being a pantie waste? Should I just stop thinking and get a rear swaybar as well to match the front? Thanks everyone for the recommendations.
I don't think there is anything "panty-like" about your concerns/questions! From what I have gathered through reading some earlier threads, you can have the car balanced, but not have a lot of ultimate grip, though it may feel easy to control at the limit. You can also have a higher grip threshold that leads to understeer. So, while the understeering might not "feel" as nice, since you have more overall grip, it may allow you to ultimately go faster through the corners. I got more than a little confused at times, but that's normal for me! :icon_confused:

I'd love to hear from folks who autocross and the different setups tried and corresponding results...
 

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Also forgot to mention, the front suspension travels a lot less independently after the bigger FSB, and a bit more NVH.
 

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Discussion Starter #16
I have to say this is the best/simplest breakdown I have found. Turn in Concepts also released a good simplified swaybar cause and effect run down. I have to say that a slightly larger front bar relative to the rear bar makes sense to me for the simple fact of weight distribution. A much larger rear bar has never really made since to me.
Subarus in general have soft springs and high ride heights on McPherson struts.
Q: What purpose does this serve?
A: It gives some decent off-road capability and provides lots of travel on each corner, while giving a smoother and softer ride around town as well.

Q: Do softer springs have a drawback?
A: Well... Suspensions are fundamentally a system of compromises. While a Porsche has a McPherson strut suspension, it's certainly not off-road capable since it doesn't come from the factory higher off the ground and doesn't require the large amount of travel, thus it won't have the same types of drawbacks that WRX/Outback/STI/etc has for higher on-pavement performance. So the Subarus do suffer a bit on pavement in lacking grip that they would otherwise have if it weren't for a "You can do it all!" type of compromise.

Q: Why would a bigger front bar be better? Won't that create more understeer?
A: The answer is both yes and no. By technical definition, it will create more understeer just like the books and what I like to refer to as "typical tuning" or "game tuning" say it does. (i.e. bar gets bigger at one end of the car, then traction is reduced at that same end of the car.) However, most folks typically don't feel it on a larger front bar for Subarus since it is only at the absolute limit of traction. When folks say that a larger front bar reduced understeer on their car, they are right in the sense that the car doesn't push (or understeer) as easily as it used to. Essentially the larger front bar raised the limits of grip up front.

Q: Ok, so if it gained understeer then how did the larger front bar gain grip?
A: The McPherson strut setup on Subarus gives a large range of travel, but it doesn't go straight up and down when it compresses from hard cornering, it travels on a slight curve. This curve affects the contact patch of the tire (i.e. how much of the tire is flat on the road surface at any given point) and for lateral lean of the tire, it's known as a camber curve. Reducing bodyroll of the vehicle through either springs or swaybars will reduce the bad end of the camber curve, which typically causes the tire to lean outwards and under hard cornering with a stock setup one is basically chewing the edges of the tire. (Note: The camber curve starts out by adding a little negative camber, but then, depending upon ride height and amount of bodyroll for the particular car's setup, goes a lot positive. Which is bad. I'm dealing here with hard cornering where one is more likely to notice suspension improvements and thus I'm ignoring the initial part of the camber curve since for performance driving it won't come into play much on a Subaru.)

Maximum cornering grip is not attained by using the very edge of one's tire, but rather as much as possible of the tire. This is why racecars have front tires that have quite a bit of negative camber (leaned in towards the car.) This way when the racecar rolls from weight transfer (bodyroll is caused by weight transfer, not the other way around) the tire ends up basically flat. In a street car, the same amount of negative camber isn't as necessary so one will find that a slight amount of negative camber is a better balance since one isn't cornering flat out around a racetrack as would a racecar. The goal is 0 camber during a corner. Racecars achieve it, street cars often do not for a multitude of reasons. But we try to keep it as close to 0 (i.e. perfectly flat or wheel straight up and down) as much as possible mid-corner.

So, preventing bodyroll will reduce strut travel, which will keep the camber curve from causing too much reduction in negative camber and going into positive camber, thus causing greater traction up front in the car and less "understeer" (by the seat of pants/speed definition.)

Q: So if the traction up front is greater, how does it cause more understeer by technical definition?
A: By technical definition, the front tires will still give way before the rear. In other words, even though the limit of traction is higher, once that limit is reached the front tires will give up before the rear because with a larger front swaybar, one is reducing grip by loading up more weight on the tire that is doing the most work. The larger bar reduces bodyroll, but in compromise fashion does it by loading even more weight onto the tire that was already doing a lot of work to start with. More weight means reduced grip. So we get say a -1 on grip from the weight loading on the front bar so that it's slightly less likely to rotate (have the rear come around) but a +3 on overall grip of the limits of the car so the car understeers only at a notably higher speed than before. That's how you get both a "yes and no" as an answer to "Does a bigger front bar cause more understeer."

Q: What about a rear bar? Does a bigger rear bar cause more oversteer?
A: Yes. A bigger rear bar changes the balance of the car in a more predictable fashion. It reduces bodyroll (for the whole car, as does a front bar, no silly-putty chassis produced these days, much less the super-stiff Imprezas of late) both front and rear. Grip goes up in both places due to a reduction in camber curve up front from less body roll but the weight loading in the rear from the bigger bar will cause it to lose more traction than gained (the rear doesn't have a camber curve like the front, and under load changes by only a minimal amount.) Thus the cornering limits are raised and by both definitions above, there is less understeer.

Hope this helps.

-Biggly
 
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