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Old 10-07-2009, 04:14 PM   #1
twizzstyle
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Default Need expert help with my suspension

I'm not looking for advice from people who have only done a handful of autocrosses, I need some expert help from a seasoned autox'er that's been doing it for many years.

My car does great at autox, feels like a go-kart... but recently at an autox practice I hopped in a friends STi that just has coilovers and a rear sway bar, and it handled WAY better than my car. My car has a lot of mods, and I wonder if maybe I've done too much and its actually detrimental to my handling now.

My car's details:
02 WRX wagon with lots of power (irrelevant)
Stock driveline (diffs, etc)

-Tanabe coilovers (KYB AGX body with 8k front 6k rear springs)
- Whiteilne 26mm rear sway (solid endlinks)
- Whiteline 27mm front sway (solid endlinks)
- Whiteline roll centre kit
- Whiteline anti-lift
- Steering rack bushings
- Strut bars front/rear
- Usually drive on RE070's, sometimes azenis

It has been a while since its been aligned, and I might've played with the camber a little bit up front, but it should be right around -2.5 camber up front (maybe up to -3.0?) about -1.2 camber in the rear, 0 toe everywhere.

The STi I drove had almost identical alignment according to the owner.

Now, I know the driveline in the STi makes a HUGE difference, but I'm leaving that out for now. It's the turn in that's bugging me, the STi was very sharp and immediate in its response, where as my car (in comparison) seemed to delay slightly. It still feels great, just in direct comparison to the STi it wasn't as good.

I wonder if maybe my front sway bar is overkill (too big)? Or maybe with a bar that big up front, I don't need as much static camber? I've thought about decreasing my camber a bit with the camber plates, but doing that will also give me toe-in which might make it worse again. I haven't had a chance to check tire temps across the tires yet to see if the camber is bad. I think at the next practice I'm going to put my stock front sway bar back on and see how that feels (although with the stocker up front and 26mm in back it might be a little dodgy). I prefer a car that is a little oversteer-prone, but I can slide my car all day long with great ease - its just this crap turn-in that I want to improve.

Also I suppose I should note that I don't, and probably never will autox competitively, so I have no concern for classing with my mods, etc. (Most of the events I do are just practices, or un-timed fun runs in a couple of clubs)

Any advice?



(hoonery from a practice last weekend... I don't always drive like a douche like this )
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Old 10-07-2009, 04:31 PM   #2
dantastic
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what wheels and tires are you running? what wheels and tires were on the STI you tried? tire pressures? could be as simple as tires. i went from azenis to kumho XS and it made a world of difference.
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Old 10-07-2009, 05:03 PM   #3
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With that front bar and those front springs, it should turn in very crisply. It sounds like you have a problem somewhere else.....like the alignment. Find out where you're at before you make any changes. The ALK should allow you to run less negative camber up front, so you may have way too much (again, referencing the bar and springs) or your toe is outta whack and feeling numb.

What kind of delay were you feeling? A tire scrubbing delay, a body pitching delay? Get tire temps first and foremost, then make mental notes on feel, then use the data to determine a possible change.

Jay
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Old 10-07-2009, 05:34 PM   #4
twizzstyle
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Yeah I will measure tire temps at the next practice. I'm on Rota's (I know...) and 225/45/17 RE070s. I think the STi had RE070's, but might have been RE-01R's.

I generally run my RE070's right around 42-45psi or so, sometimes slightly less up front (40ish). I don't like my azenis as much as my RE070's, but I have the azenis just for gearing (they are 205/45/16's so about an inch smaller diameter than stock, helps keep the revs higher, with a loss in handling).

I don't even think delay is the right word. Driving my car it feels great... but then if I go back to back with the STi, it just felt "better". I found myself turning too much in the STi, then if I went back to my car, I wasn't steering enough (steering ratio difference?).

If my camber isn't exactly where it was last time I had it professionally aligned with 0 toe, then it might be a little more negative, which would give me some toe out correct? Which I would think would improve my turn in.
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Old 10-07-2009, 07:20 PM   #5
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Quote:
but recently at an autox practice I hopped in a friends STi that just has coilovers and a rear sway bar, and it handled WAY better than my car.
What kind of coilovers were on the STi? You have...

Quote:
KYB AGX body with 8k front 6k rear springs
which is as bottom end adjustable shocks as one can get. Stock STi stocks have better valving than KYBs.

I'd start looking there. Also, 6K/8K may be too much spring for the valving of the KYBs to handle. 400ft/lb is usually the top of the range and the 8k springs are over that limit. Their 'sweet spot' is usually around the 200-300 ft/lb range, IIRC.

--kC
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Old 10-07-2009, 09:43 PM   #6
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I dunno about the steering ratio difference....but if there is one, it would be profoundly noticable in back to back runs.

That's one thing that I noticed in driving my little FSP brighton and the mccanixx ESP WRX. I use a 300mm race wheel compared to his stocker, and the amount of hand movement required for his car is much more than mine.

Jay
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Old 10-07-2009, 10:11 PM   #7
twizzstyle
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Quote:
Originally Posted by KC View Post
I'd start looking there. Also, 6K/8K may be too much spring for the valving of the KYBs to handle. 400ft/lb is usually the top of the range and the 8k springs are over that limit. Their 'sweet spot' is usually around the 200-300 ft/lb range, IIRC.

--kC
Yeah the Tanabe's are crap, I got them just because they were cheap ($400 used) and gave me corner weighting ability. I'm not sure what the other car had, he told me once, I know they're not crap though.

My wheel is 330mm.

Thanks for the tips guys!
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Old 10-08-2009, 12:39 AM   #8
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also i am wondering if it is the different speed steering rack you are feeling. if im not mistaken the '02 wrx had a slower steering rack rate than the STi's.
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Old 10-08-2009, 01:40 AM   #9
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My first question would be what spring rates are on the STI and what tires are on it.
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Old 10-08-2009, 01:05 PM   #10
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Quote:
Originally Posted by tratpop View Post
also i am wondering if it is the different speed steering rack you are feeling. if im not mistaken the '02 wrx had a slower steering rack rate than the STi's.
That would certainly make turn-in feel crisper.
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Old 10-08-2009, 07:47 PM   #11
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From personal experience comparing the wrx and STi at autox I think the following add up to the difference you are feeling:

1) STi out of the box has more caster
2) STi rack quicker ratio
3) STi will rotate better coming out of a turn due to front LSD and variable center diff.

I also noticed when I added a lower front tie bar to my wrx it help with corner exit rotation, I'm not sure how but it gave the car better grip on corner exits. The STi has a factory tie bar already (extra bracing).

If it's the inital turn in thats slow, your other factory bushings could be getting soft.

Again from personal experience, when I replaced all the suspension bushings for a ST preped gen II integra and then compared it to another ST preped gen II integra, the response and turn is was so amazingly different. One felt like a go cart and the other a mini van (at initial turn in).
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Old 10-09-2009, 01:54 PM   #12
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Ok, talked to the STi owner, he has Helix DNA coilovers, with 8k front 6k rear springs. So same springs, but likely better damping (but can't be much better, those coilovers are $699 brand new!)
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Old 10-09-2009, 10:54 PM   #13
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Here's my advice:

Get better shocks, at least some koni's
Get better tires
You need be running at least 3 deg of camber up front. Anything less and you are not maximizing the contact patch.
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Old 10-10-2009, 09:48 PM   #14
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This has been asked several times already, and you haven't answered it yet :

What tires/wheels were on the STi?

You'd be amazed how tire differences can make a car feel crisp on turn-in or just like mush. The difference between Kumho V710s and Hoosier A6s isn't as noticeable as previous iterations of those tires, but it's still a noticeable difference to those who've been running for a while.

I'm willing to bet that tire differences are going to account for a lot of the difference that you felt.
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Old 10-11-2009, 09:22 PM   #15
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Quote:
Originally Posted by CamaroFS34 View Post
What tires/wheels were on the STi?
They were either RE070's or RE-01R's, I can't remember.
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Old 10-12-2009, 03:39 PM   #16
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Old 10-12-2009, 06:05 PM   #17
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As always I want to let you all know that you can ignore my posts at any time.

First of all the whole setup seems funky to me. (not trying to bash you or anything) What has worked for my WRX is: stock or not too stiff front bar, softer springs up front than the the rear. doesn't matter if they are 450lbs front and 600lbs rear or some other combination. Here is my Nationally competitive setup just to give you an ideea (I will not list all the small stuff just the important things)

Stock front Bar, Cobb Rear, 600lbs front, 850 rear, good double adjustable shock, almost zero aligment but with a hint of front and rear toe out. Front spacers, ~4deg of camber in front and 2.2 in the rear.

Please note tha this is a bit extreme in terms of spring rates but I developed it for Lincoln's concrete (improved grip). It is a bit harsh for the beack seat but while driving is not too bad with some good shocks.

The WRX needs help to rotate due to crapy diffs that is why you want a stiffer rear. also you don not want your front too stiff (allthough will FEEL good) it will yeld slower times, you need the fron end to dig in in a corner ... of course you need to keep a balance because a too soft of a front end will be slow to react in slaloms and will lose camber when leaning in corners ... There needs to be a balance .... Of course small shock and toe/ride height adjusments can be made for different courses/surfaces.
P.S. I do think that I have one of the faster STX WRXs ot there (yes, yes I said that) and allthough I drive like **** I managed some decent results out there.

Good luck.
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Old 10-12-2009, 11:54 PM   #18
twizzstyle
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Great advice, thanks!

Sounds like overall I just need more camber, and a slightly smaller front bar, and maybe a better tire than the RE070.
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Old 10-12-2009, 11:55 PM   #19
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Quote:
Originally Posted by treicoaie View Post
Front spacers
What do the spacers do for you?
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Old 10-13-2009, 06:51 AM   #20
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Semi-hijack.... the springs on my coilovers have "8K/6K" rates, I used to have a calculator bookmarked but can't find the conversion to lbs/in. Anyone know roughly what that equates to off the top of their head?
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Old 10-13-2009, 07:11 AM   #21
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1k = ~56lbs

--kC
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Old 10-13-2009, 02:31 PM   #22
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Quote:
Originally Posted by twizzstyle View Post
What do the spacers do for you?
They will wear your wheel bearing quicker....
Wider track= more front grip .. also the way my car is set up I need at least a 5mm spacers just so the tires wouldn't rub against my springs.
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Old 10-13-2009, 03:04 PM   #23
twizzstyle
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Quote:
Originally Posted by treicoaie View Post
They will wear your wheel bearing quicker....
Wider track= more front grip .. also the way my car is set up I need at least a 5mm spacers just so the tires wouldn't rub against my springs.
ha, ok. I guess there's another thing the STi has up on me, track width... my car is a wagon.
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Old 10-14-2009, 01:00 PM   #24
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Quote:
Originally Posted by treicoaie View Post
They will wear your wheel bearing quicker....
Wider track= more front grip .. also the way my car is set up I need at least a 5mm spacers just so the tires wouldn't rub against my springs.
I'm pretty sure the WRX could take a 20mm spacer up front.
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Old 10-15-2009, 12:55 PM   #25
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Quote:
Originally Posted by treicoaie View Post
<snip>
What has worked for my WRX is: stock or not too stiff front bar, softer springs up front than the the rear. doesn't matter if they are 450lbs front and 600lbs rear or some other combination. Here is my Nationally competitive setup just to give you an ideea (I will not list all the small stuff just the important things)

Stock front Bar, Cobb Rear, 600lbs front, 850 rear, good double adjustable shock, almost zero aligment but with a hint of front and rear toe out. Front spacers, ~4deg of camber in front and 2.2 in the rear.

Please note tha this is a bit extreme in terms of spring rates but I developed it for Lincoln's concrete (improved grip). It is a bit harsh for the beack seat but while driving is not too bad with some good shocks.
Car 95/195 STX, I drove it well enough for a 7th place this year. Our car mimics treicoaie, although we both arrived at these suspension settings completely independently.

650F/800R
COBB tubular bars, front and rear (rear is as stiff as it will go)
AST 4200s, 3F/7R compression, 5F/11R rebound
toe -5/16"F/0"R
camber -3.3*F/-2.1R

We stiffened the rear to reduce front wheelspin and to work with our rear camber. We stiffened the front to reduce weight transfer under decel, which causes inside rear wheel lift. Rotation can be induced by a quick lift of the throttle then rotation is maintained with the throttle back down. It is also stable under braking- no snap oversteer when braking points are in the middle of corner exit. These settings have been run on low and high altitude courses, smooth asphalt and choppy concrete (and everything in between), all with similar driving characteristics.
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