getting a better handling car on good summer rubber

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avriette
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getting a better handling car on good summer rubber

Post by avriette »

I keep pretty nice summer rubber (I'll be posting a separate thread on rubber elsewhere when I get answers here) on the car year round and I find that I am sliding all over the place when I ...... inspire the car to move that way. This is bothersome, and I'd like to fix it. Julian mentioned the kartboy endlinks ($200 for the f&r set). He also mentioned camber bolts and I agree with his -2.5F and -1.5F rear. But he said (I think) I needed to buy two additional camber bolts. Where do I do that?

Also, I had asked Mike at Don Beyer Subaru to install the SPT front and rear sways and he says that while he is not convinced, he suspects that the "SPT" sways are just the "STI" sways that they sell to the non-STI crowd. So now I'm looking at aftermarket sways too. Is whiteline basically the way to go? Julian pointed me at these:

Rear sway at $212:
http://turninconcepts.com/product_info. ... ucts_id=61

Front sway at $188:
http://turninconcepts.com/product_info. ... ucts_id=41

The strange thing is they're both 24mm. Can anyone comment on this in particular or sways on the STI in general? I'm willing to buy the endlinks and the sways (do I need any additional pieces?) if the increase in handling is going to be there. I'm tired of the car sliding around. Like, is it going to be $600 better in the turns?
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complacent
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Re: getting a better handling car on good summer rubber

Post by complacent »

you'll want endlinks on the rear bar. i've seen more than a few oem's fold over. even on stock diameter.

i've seen autoxers go as stiff as 32mm up front. not necessarily practical for the street (or the track for that matter) but it does help keep the front end planted and gives that yummy front diff the chance to do its thing.

i think the bars make a pretty decent difference. i'm not sure what you'd quantify as $600 better though.
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Re: getting a better handling car on good summer rubber

Post by Sabre »

You'll definitely see the most benefit from the rear sway, but this combo:
Sways + endlinks + proper alignment
will get you big performance gains in the corners. To get the next level of performance, you're looking at struts/springs or coilovers.

Some background:
The stock STI has two camber bolts up front and is fixed in the rear. To get aggressive camber, you add two more bolts to the front and two in the rear. To get any more aggressive, you need to go to camber plates.

The stock STI swaybars are 21mm in the front and 19mm in the rear.

The stock endlinks (see picture below) are very fragile. With an upgraded sway, they are most certainly going to bend.

Links to the stuff we talked about:
Camber bolts
Rear Sway - Whiteline STi 24mm adj. rear swaybar
Front sway - Aggressive street - Whiteline STi 24mm adj. front swaybar
Front sway - Race - Whiteline STi 27mm adj front swaybar
Straight Endlink Combo - Kartboy front and rear endlinks

Stock STI endlinks:
Image

Karyboy endlinks:
Image
Sabre (Julian)
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Re: getting a better handling car on good summer rubber

Post by avriette »

Doesn't a 27mm front sway (vs 24mm out rear) make it understeer like a pig? I don't get whiteline's setup. Everyone else seems to be going big out back and skinnier up front (neutral tending towards oversteer).
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Re: getting a better handling car on good summer rubber

Post by avriette »

bump and edit: is it the adjustment to the front bar (being much thicker than the rear bar, but adjustable) that makes it not understeer severely?

i'm seriously wondering because the whiteline guys do really well at the track and everyone seems to agree that their stuff is where it's at in terms of sways.
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Re: getting a better handling car on good summer rubber

Post by Sabre »

I think that with a 24m front and rear with the rear set to full stiff, you will be neutral to slightly oversteer. Set the front to full stiff and you'll get understeer.
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Re: getting a better handling car on good summer rubber

Post by avriette »

Sabre wrote:I think that with a 24m front and rear with the rear set to full stiff, you will be neutral to slightly oversteer. Set the front to full stiff and you'll get understeer.
Maybe then I should go with someone like Perrin who has a skinny front and thick rear so the car is much more prone to oversteer. With the endlinks and camber of course, just different sways. Just a different preference for style of driving, I think.
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Re: getting a better handling car on good summer rubber

Post by complacent »

avriette wrote:
Sabre wrote:I think that with a 24m front and rear with the rear set to full stiff, you will be neutral to slightly oversteer. Set the front to full stiff and you'll get understeer.
Maybe then I should go with someone like Perrin who has a skinny front and thick rear so the car is much more prone to oversteer. With the endlinks and camber of course, just different sways. Just a different preference for style of driving, I think.
Perrin also sold a ton of inlet tubes that collapsed under boost... I wouldn't take their products or theories as golden. Just my .02usd, ymmv.
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Re: getting a better handling car on good summer rubber

Post by avriette »

looks like whiteline makes an adjustable 27mm rear bar and a 22mm adjustable front bar. maybe that's the way to go.
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Re: getting a better handling car on good summer rubber

Post by PGT »

Perrin is horrid for QC. They tend to beta-test on customers....'05+ Legacy owners got to learn the hard way that Perrin didn't bother with real world testing before we bought their product. Any swaybar that HITS the control arm is a half-assed product. Instead of standing behind the product, they accused owners of being a) morons b) incompetent shadetree mechanics or c) both
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Re: getting a better handling car on good summer rubber

Post by avriette »

Okay, I am sorry I bumped my own thread that was mostly dead. I have a question that has been nagging at me since, oh, this afternoon, and I figure somebody (probably Zak) has a good answer for me.

So, let's say that the car was moving around the top of fourth gear through a downhill, uh, chicane. This is in Arlington somewhere. Don't worry, it was a closed course and a trained driver. The car swayed a lot, but mostly stuck to the road. There was a little bit of complaining in terms of tires wailing (you know, like X-wing noises), and the chassis seemed to hunch down in the front really hard (losing lots of speed - top of fourth to middle of second kind of turn).

A couple things come to mind.

First, the car still (mostly) understeers when it is under heavy, heavy braking. Shouldn't the rear be lighter, and the rear want to come out a bit more? Why is that not happening?

Second, there are certainly ways to stiffen up the chassis and ways to make it "handle better." We've talked about some of them here, Julian and I have talked about them a lot offline. But I find myself thinking back to what was ultimately chassis flex and body roll and how the car still stuck despite it flopping around like a fish. If the chassis were stiffer (heh, heh), that slop would not have been taken up by the body, and would instead have been transferred (presumably) to the tires. That would mean that, since the tires are at the limits of their ability to hold the ground (we can sense this based on the noise, right?), they would be under greater demand to hold and would instead lose grip and slide. Sliding at the top of fourth through a turn sucks a little. Do I have this right? Not the sucking part, but the part about the chassis maybe having an "appropriate level of slop in it"?

Lastly, and Julian has I think answered this for me, putting slicks on the car is a bad idea, right? Ordinarily (and before I had lots of talk with J about this) I would think, okay, I don't care about treadwear, so I will put some slicks on the car (those 30- and 40-wear tires) and just go tear shit up. But the problem with this is the exact opposite of the "appropriate level of slop" problem, right? If I put slicks on the car and flog it approximately as hard (on a closed course with a trained driver), that force is translated back through the tires and into things like end links, sway bars, and control arms, and rather than slide around on the tire, it's going to stick, and I'm going to break parts. Is this approximately correct?

See, I'm thinking of buying new tires by around the end of the summer, and I'm at the point where I am pretty familiar with the limits of what it can stick to. I'd like "more stick." But it's starting to occur to me that a sloppier chassis that is also stronger with a slicker tire might be the better route than a very stiff chassis and a slicker tire (which might still slip), or a slicker tire with the same chassis (which might rip parts), or a stiffer chassis with the same tire (which will probably slip even more).

And of course I use the term "slicker" here as an adjective, not a noun. I am speaking about tires, not jackets.

This is mildly confusing, and at one point I think I had the answers to these questions, but in college, I didn't have enough money to own an STI and we didn't even get them here in the States.

If I haven't mentioned, the car is on the (now discontinued) RE-01R. They've got okay tread left but I know they're going to need to be replaced by the end of summer. And no, I don't mind driving on slicks in the winter if it means on sunny days they will be fine and I can just drive slower in the snow and rain. Gosh, I say stupid things like that a lot. Sooner or later somebody is going to call me a squid. Thanks in advance, I realize I talk a lot.
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Re: getting a better handling car on good summer rubber

Post by Raven »

First, Heavy braking will always cause understeer. The tire only has so much force it can exert. If you use all the force to stop the car, there's none left to turn.

Second, I think you're really over thinking chassis flex. Also I think you're attributing things to chassis flex that really are just a car bouncing around on a poor road surface.
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