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GRs in STU autocross
GRs in STU autocross
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Old 12-24-12, 02:12 PM   #41
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Default Re: GRs in STU autocross

Thanks, I'm pretty stoked.

700/900 sounds pretty awesome, it would be cool to have the ability to set up from scratch. I look forward to future post, with pics of course. Are you planning on stock sways??
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Old 12-24-12, 05:15 PM   #42
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Default Re: GRs in STU autocross

Not sure on the sways. Here's some info I've either calculated or collected. Feel free to jump in if you see something that needs adjusted. We can use this for future reference:


GR SWAY BAR INFO
OEM Front (.67 Sway Motion Ratio)
2010 STI bar: 20 mm (400 lbs/in)
2011 STi bar: 21 mm (486 lbs/in)

Eibach front: 25 mm tubular and 2 way adjustable (not sure this is correct)
Position 1 = 82 N/mm (465 lbs/in)
Position 2 = 93 N/mm (528 lbs/in)

RCE front:
25.5 tubular and 2 way adjustable,

Position 1 = 22.7 effective rate (664 lbs/in)
Position 2 = 23.5 effective rate (762 lbs/in)


Perrin front:
22mm solid and 2 way adj
50% Higher Rate than 20mm / Effective Rate =600 LBS/IN
85% Higher Rate
than 20mm / Effective Rate =740 LBS/IN

Perrin front: 25mm solid and 2 way adj
160% Higher Rate than 20mm / Effective Rate =1040 LBS/IN
215% Higher Rate than 20mm / Effective Rate =1260 LBS/IN


OEM Rears
(.59 Sway Motion Ratio / .78 Shock & Spring)
2012 WRX bar: 16 mm / bar rate: (178 lbs/in)
2010 STI bar: 18 mm / bar rate: (285 lbs/in)
2011 STI bar: 19 mm / bar rate: (354 lbs/in)

Eibach rear: 22 mm tubular and 2 way adjustable
Position 1 = 58 N/mm (332 lbs/in)
Position 2 = 76 N/mm (432 lbs/in)


RCE rear:
25.5 tubular and 2 way adjustable,
Position 1 = 22.7 effective rate (721 lbs/in)
Position 2 = 23.5 effective rate (828 lbs/in)


Perrin rear: 22mm solid and 3 way adjustable,

Position 1 = 140% (527 lbs/in)
Position 2 =
185% (656 lbs/in)
Position 3 = 240% (869 lbs/in)


Adding thread Mind started with good info: Springs, Swaybars, Wheel Rates and Frequency

Last edited by senna1a; 03-28-13 at 04:52 PM. Reason: adjusted rates slightly - some were rounded earlier
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Old 12-25-12, 05:55 PM   #43
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Default Re: GRs in STU autocross

Quote:
Originally Posted by senna1a View Post
Here's some info I've either calculated or collected.
Excellent! Thanks for the contribution.

Koni DAs and 700/900s sound like the start of something awesome. Are you getting the valving done by Lee?


As a side note, I'm thinking of picking up a set of RCE bars soon to run until I step up spring rates. I'll post thoughts if/when that happens.
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Old 12-26-12, 07:38 AM   #44
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Default Re: GRs in STU autocross

Some additional observations after a busy season (30+ events ):

- The GR chassis loves front camber. No surprise there, as the GD loves it, too. Having experienced a significant increase in camber, I now feel terrible for those poor souls running STIs in B Stock...

- Star Specs + Carolina summer heat = grease. If you're running summer events south of Anchorage, get a nice water sprayer and keep that mf full. I have to soak my fronts between runs, and the rears require at least a quick spritz. Thank goodness I did Evo School in November -- all that hot-lapping without time to spray would have murdered my tires.

- Leave the center diff in auto. I like a neutral to loose car, so I tried out full open (one bar) in the beginning, but eventually gave up trying to beat the computer.

- Feel free to run the car close to empty on fuel. I've made up to four 60 second runs after the fuel light came on, and never experienced starvation.

- Get wide wheels. The 245/40 Dunlops stretch nicely on my 9.5" wheels and look a hell of a lot wider than 245s! As previous research indicates, turn-in and transitioning is quite crisp.

- Stick with 18" wheels. I really wanted to run 17s (cost, weight, cost, gearing, cost), but had issues running into the rev limiter in second on most courses when I was still using the OEM BBS wheels. Given the big concerns of prolonged limiter-banging in our cars, I thought it wise to keep the same overall diameter. In fact, I would gladly give up some gearing advantage to run a larger diameter setup, were it feasible.


I'll add more as I get even more familiar with the car.
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Old 12-26-12, 09:17 AM   #45
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Default Re: GRs in STU autocross

Very good notes; and yeah, Lee/Gordon are always willing to help. I haven't run much autox the last 4-5 years, just a couple Pro's this past year in a WRX, so will be good to get used to the STi and it's diff magic. Did you run more ashpalt or concrete running auto? Did you try auto- at all for concrete or auto+ for colder/rain events?

I like the idea of the RCE sways. I'm considering getting a set along with some springs with rates similar to yours to compare to 700/900 with stockish sways. The overall wheel rate should be similar.

I've taken my limiter from 6750 to 7200, but left the limiter light so it'll come on at 6750 and had everything taper off so no hard limiter. I'll have a set of 17's and 18's, but will more than likely run 18's for all but tight courses.

I'll keep adding thoughts/etc as well. Feel free to pokes holes in ideas as I typically explore a bunch of possibilities to find the right mix.
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Old 12-26-12, 09:28 AM   #46
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Default Re: GRs in STU autocross

Good stuff, I'll chime in too. Close to 20 events this year with two clubs. FYI, both of our venues are on bumpy asphalt.

-2.5* camber is totally fine for DD, no strange wear patterns.

Bring a sprayer and wet down the intercooler and radiator, especially for two driver cars.

Hankook RS-3s for the summer, they love heat and only get faster the more they are abused. Good starting pressure is 38psi all around.

Get the lightest wheels you can find in 9"-10" width.

I'll agree with the stretch but not on the 18s. It might be the courses I run are tighter and more technical, but the gearing and weight advantage for the 3.5mph top speed loss is well worth it. If I'm constantly on the limiter I'll short shift to third and heel toe in the next braking area. This season we had about 8 courses where this was necessary, in each situation I was hitting 70+ so shifting would have happened no matter what.

Depending on the course you can get the car to rotate better by either putting it in Auto+ or increasing rear tire pressure. Auto+ is great for tight technical courses but is unstable at high speeds. More rear tire pressure isn't as drastic, so is better for fine tuning rotation.

Auto- is worthless unless it's a super fast and open course and the car needs more stability.

Power through everything and get on the throttle as early as possible. The diffs can only do their voodoo under power so stop being a pansy and use the pedal on the right. The car will hold, just plan ahead and rip it.

Good mounting point for a camera is on the dome light. Use one of the slightly curved adhesive mounting clips and attach it to the right (passenger) side of the light. This way you can see how well you are looking ahead, if you have smooth inputs and check your line all in one video. Winning!!
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Old 12-26-12, 02:21 PM   #47
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Default Re: GRs in STU autocross

Quote:
Originally Posted by senna1a View Post
Did you run more ashpalt or concrete running auto? Did you try auto- at all for concrete or auto+ for colder/rain events?
All the sites I ran this year were asphalt except one, which was concrete. I think there were three or four events where it was either raining or there was standing water on course in spots. In all of those cases, I kept it in plain auto.

I did mess around with Auto - in a few events, but ended up just leaving the diff alone in the end.

Quote:
Originally Posted by senna1a View Post
I like the idea of the RCE sways. I'm considering getting a set along with some springs with rates similar to yours to compare to 700/900 with stockish sways. The overall wheel rate should be similar.
That is my thinking as well. I'm pulling the trigger on them today, so I'll have them before the first event of 2013. Now, if Dunlop will just come through with some ZIIs...

Quote:
Originally Posted by senna1a View Post
I've taken my limiter from 6750 to 7200, but left the limiter light so it'll come on at 6750 and had everything taper off so no hard limiter.
I think raising the limiter with a tune is more appealing to me than gaining power/torque. We'll see if I grow a set this year, and forsake the factory warranty.

Quote:
Originally Posted by DelJago View Post
I'll agree with the stretch but not on the 18s. It might be the courses I run are tighter and more technical, but the gearing and weight advantage for the 3.5mph top speed loss is well worth it.
It is definitely course-dependent, but from my experience, a lot of transitions around here are just out of reach for our second gear (with stock rev limit). On our bigger courses (ZMax Dragway in Charlotte, Cherry Point Marine Air Station), a decent amount of each course is often spent in third, but the "tweener" spots make staying in second more advantageous than two shifts.

On smaller courses, there is no question that more speed in second would pay huge dividends. Again, this is simply my experience around NC/SC/VA.

Quote:
Originally Posted by DelJago View Post
Depending on the course you can get the car to rotate better by either putting it in Auto+ or increasing rear tire pressure. Auto+ is great for tight technical courses but is unstable at high speeds. More rear tire pressure isn't as drastic, so is better for fine tuning rotation.

Auto- is worthless unless it's a super fast and open course and the car needs more stability.
You've got them backwards.
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Old 12-26-12, 03:54 PM   #48
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Default Re: GRs in STU autocross

Are either of you considering additional bushing upgrades?
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Old 12-26-12, 04:41 PM   #49
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Default Re: GRs in STU autocross

I've already got the Whiteline front control arm and rear upper control arm (camber adjusting) bushings sitting on my workbench. The fronts will get done whenever I pull the front coilovers next, and the rears might get done before Dixie NT.

I'm not exactly looking forward to re-aligning and corner balancing the car.
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Old 12-26-12, 07:17 PM   #50
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Default Re: GRs in STU autocross

Quote:
Originally Posted by em99sport View Post
You've got them backwards.
No way, I've played with this all season and Auto+ definitely allows the car to step out more than Auto while Auto- doesn't rotate much at all.

Auto+ sliding at 1:06
Auto is stable at 1:09

Side by side only because YouTubeDoubler is awesome.

If you can control it I think Auto+ can be faster which is why I try it after I get a couple runs in and feel more confident on the course. Unfortunately it's too loose for my hamfists, especially on this course where I was in third through those offsets.

Anymore I stick with Auto and adjust via tire pressue.
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