Author Topic: Solstice GXP 1st place in High Speed Autocross (Read 12777 times)

Graywolf · « **on:** May 30, 2012, 09:48:42 PM »

This past weekend I won 1st place in X prepared @ Blackhawk Raceway over Subaru WRX sti 's, Mitsibishi Evo's and Camaros in Hi Speed Autocross. It was a crazy weekend for me since I had to play in my band,4hours sleep Friday ,4 hours Saturday and only 2hours sleep Sunday and Raced on Monday. I made only 3 timed runs and was pleased with my time. The track had 2 rough spots on turns where the asphalt was tearing up and I wanted to save my new A6's. The other competitors made 8 timed runs but noboby beat my fastest time. They made me change from A prepared because of new rule on car classes. I would have won in that class also which had all Corvettes and one Bmw m3. Also smoked a Dodge Viper by 2 sec's Finally got the car running great 25lbs boost in all gears

crisco · « **Reply #1 on:** May 30, 2012, 10:02:31 PM »

Congrats! Graywolf!

Gentleman Jack · « **Reply #2 on:** May 30, 2012, 10:39:17 PM »

Wow! Great work!

Sly Bob · « **Reply #3 on:** May 30, 2012, 10:41:40 PM »

Wow, sounds like some great driving. Nice work!

1LILNDN · « **Reply #4 on:** May 31, 2012, 12:28:28 AM »

Great driing for not having alot of sleep . Beating an STI is doing something." Congrats "

Kelu · « **Reply #5 on:** May 31, 2012, 01:45:26 AM »

Wow, congrats for such a performance

and thank you for sharing the joy with us

DeepBlueGXP · « **Reply #6 on:** May 31, 2012, 05:33:42 AM »

Sweet. Glad to hear your GXP is working great.

ihawk95 · « **Reply #7 on:** May 31, 2012, 06:26:57 AM »

Way to go!!! Nice job!!!

Critterman · « **Reply #8 on:** May 31, 2012, 07:35:13 AM »

HINT to self. Don't get any sleep leading up to race day.

Great Job.

Dr. Gronk · « **Reply #9 on:** May 31, 2012, 10:16:10 AM »

Wow, good job! Sounds like your car wasn't the only thing running in all gears at 25lb boost. Get some much deserved rest!

POS VETT · « **Reply #10 on:** May 31, 2012, 10:38:52 AM »

Nice work !

Our result was different. My wife took the Solstice to an autox for the first time this past Sunday to see what it could do after the coilover, chassis braces, and sway bars. It ran on the stock tires and wheels with quite a bit of negative camber up front (-2.2 degrees). It didn't have any problem putting down power but the car had massive understeer. Changing damper setting had very little to no effect; the car just plowed. So bad that she didn't want to race it anymore and Monday she switched to the Z06.

Sol Asylum · « **Reply #11 on:** May 31, 2012, 01:19:45 PM »

Quote from: Critterman on May 31, 2012, 07:35:13 AM

HINT to self. Don't get any sleep leading up to race day.

Great Job.

Hint to Critter. Drive around the cones.

Carbon Sky · « **Reply #12 on:** May 31, 2012, 02:51:28 PM »

Quote from: POS VETT on May 31, 2012, 10:38:52 AM

Nice work !

Our result was different. My wife took the Solstice to an autox for the first time this past Sunday to see what it could do after the coilover, chassis braces, and sway bars. It ran on the stock tires and wheels with quite a bit of negative camber up front (-2.2 degrees). It didn't have any problem putting down power but the car had massive understeer. Changing damper setting had very little to no effect; the car just plowed. So bad that she didn't want to race it anymore and Monday she switched to the Z06.

My guess is the excessively stiff front spring rate and front sway bar. Put the stock front sway bar back on, leave the ZOK sway bar in the back, and if you can, swap the front springs for lower rate springs.

You aren't effectively transferring weight to be able to get the most out of the tires, and as you have now realized, you've actually decreased the handling performance.

LatinVenom · « **Reply #13 on:** May 31, 2012, 05:19:18 PM »

I have a question. How much of the problem is the OEM tires?.

ihawk95 · « **Reply #14 on:** May 31, 2012, 06:02:08 PM »

Quote from: LatinVenom on May 31, 2012, 05:19:18 PM

I have a question. How much of the problem is the OEM tires?.

Ditto that question. They aren't exactly a great autox tire.

Carbon Sky · « **Reply #15 on:** May 31, 2012, 06:28:27 PM »

If it were just the tires the overall level of grip would be lower, but the balance between under and over steer would remain the same. So if he's complaining about outright grip, sure it's the tires. But if it's a matter of over/under steer, it's the suspension setup.

Treeman · « **Reply #16 on:** May 31, 2012, 08:01:59 PM »

Congrats! How fast is hi speed?

elff · « **Reply #17 on:** May 31, 2012, 10:15:11 PM »

Our cars plow if the front and rear sway bars are the same stiffness.
I've done a bunch of autoXing and I run the FE3 swaybar up front and the ZOK swaybar rear and it's solved the understeer issue.
You also need to make sure the rear shocks/springs are stiffer than the fronts.

Your kappa suspension needs some tuning

POS VETT · « **Reply #18 on:** June 01, 2012, 11:43:58 AM »

The coilover has stiffer springs in the back, 5 kg/mm front and 6 kg/mm rear. The sway bars are indeed GXP ZOK; roll stiffness should increase more in the back than in the front I believe. We've decided to limit the Solstice just for street duties.

At any rate, we've been to "hi-speed" autoxes where the Z06 hit rev limiter in the first gear (~62 mph) and in a few cases, second gear got the car into 70-75 mph range; things got very exciting very quickly.

elff · « **Reply #19 on:** June 01, 2012, 11:52:27 AM »

Go back to the FE3 front sway bar and the understeer will be gone.

Carbon Sky · « **Reply #20 on:** June 01, 2012, 12:06:30 PM »

Quote from: elff on June 01, 2012, 11:52:27 AM

Go back to the FE3 front sway bar and the understeer will be gone.

I run the same setup, and it's far more neutral than when you run ZOK bars front and rear. That added front roll stiffness is causing your understeer.

But hey, you can always keep the suspension setup that explains why you're under steering, and upgrade the tires, and improve grip, but maintain the same balance of under/over steer. Or you can change the front bar back to eh FE3 bar which shouldn't cost you anything but some time, and see if you like it, and decide what you want to do from there.

But all those suggestions it's the tire and not your suspension setup are leading you in the wrong direction.

Gentleman Jack · « **Reply #21 on:** June 02, 2012, 01:55:14 AM »

I think it's the tires.

Carbon Sky · « **Reply #22 on:** June 02, 2012, 01:06:04 PM »

Quote from: Gentleman Jack on June 02, 2012, 01:55:14 AM

I think it's the tires.

So if he upgrades a whole set of tires, front grip will improve, but so will rear grip, so whatever the increased grip in the front, that would cause a decrease in understeer, will be counter acted by an increase in rear grip, which will make it understeer all over again.

Care to explain how tires would change the balance, and not just the overall grip?

Look for yourself

Understeer: reduce front or increase rear anti-roll/ sway bar settings.
Oversteer: increase front or reduce rear anti-roll/ sway bar settings.

http://www.rapid-racer.com/suspension-tuning.php

So please, I'd love to hear how increasing the grip at all four corners will reduce understeer. Because hey, I've only been studying this stuff for years, and have only been applying it to formula SAE cas, and many modified road cars, and have been accepted into a masters of mechanical engineering, with a focus on automotive engineering, so it's not like I know what I'm talking about.

But in all seriousness, as far as everything they teach in mechanical engineering, it's just not the case that upgrading the tires, and leaving the suspension alone will change the under/over steer balance.

elff · « **Reply #23 on:** June 02, 2012, 01:13:07 PM »

I do believe GJ was just kidding because someone else said don't mention the tires

Gentleman Jack · « **Reply #24 on:** June 02, 2012, 02:03:57 PM »

Who said anything about 4 tires?

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Author Topic: Solstice GXP 1st place in High Speed Autocross (Read 12777 times)