ChopsMcgraw

Did my first autox yesterday in phoenix, however I was woefully underprepared (no air, no time for a course walk). By the last run the front tires (at 34 psi) had given up and I could no longer get the car to turn in. But, with such a small sidewall area, how much difference are tire pressures going to have, and what effect would a stiffer front bar have? Its been my experience the stiffer front bars generally increase understeer, and since I'd like to stay in BS, there wouldn't be the corresponding increase in rear bar stiffness to balance the car out. Any BS guys willing to share their setup experiences? My run was good enough for 2nd out of 21 in NV1, but I got whomped in PAX, somewhere in the 70's. While I need a bunch more seat time, it'd be nice to have a nice beginning setup, it was plowing like a caprice by the last run, was a full 2 seconds slower- Thx-


Chops
Lightning Yellow Base 6sp
Scenic Yuma, AZ

epitrochoid

what do you do when there'd understeer? just pull the ol' ebrake!

on a serious note, carefully analyze your driving technique before worrying about the car. are you sure you're keeping the car balanced on turn in?

ChopsMcgraw

According to my butt, yes. To someone else, who can say... The other runs were very neutral in balance, the car could rotate when you asked it too, not so in the last run... I was more agressive, but not much more aggressive than I had been-


Chops

John V

iTrader: (1)

Sounds like you were just going into corners too hot, or trying to brake and turn simultaneously. Slow down, turn in, get on the gas as soon as possible. It's all about exit speed.

On street tires you can measure the rollover of the front tires to check the pressures. It's a good rule of thumb that you should see scuffing down the edge of the outer treadblock, but no farther than about half way. I suspect that your pressures actually *increased* in the front tires throughout your runs as the tires heated up, and that you weren't rolling over too far. Sounds again like a case of overdriving.
On a car like the RX-8 which has "proper" suspension geometry, in general a front bar will promote understeer. However, it really depends on a lot of things. The only way to really know is by taking tire temperatures. If the outside edges of the front tires are getting much hotter than the center / inside and your camber is already at max negative, a front bar may help by limiting body roll and the resultant positive camber situation. It'll have the added benefit of making the car faster in transitions.

It's been a while since I've been on street tires, but I bet Clyde can give you some starting pressures. I'd take a stab that you'll want 40psi front and rear, which will allow you some room to bleed them down as they heat up.

Good luck and have fun. I wouldn't worry too much about the hardware now, just drive!

om-nc

I started at 37 psi all the way around and dropped to 34 rear and 36 front. This is with OEM tires. It helped a lot but my son found out the hard way about brake then turn as he took out 6 cones at the exit feature. A hard lesson of terminal understeer. FWIW I have the racing beat front bar and it helped tremendously.
Paul

clyde

I'm not sure where my notebook with my street tire notes is right (but I'm betting that it's in the car and it's too f'ing cold to run out there now), but I think I wound up at ~37 in front. The rears went up and down a few pounds from there depending on the course. Potenza RE040s. I never had a problem with overheating last summer, but I don't think the car ever had more than four runs in a single run group either.

Ophitoxaemia

i found the stock tires dont like heat and require cooling even with a single driver.

also, in stock form, it is easy to get the front on the bump stocks and create instant and impressive understeer.

james

Dark8

I ran with JICs and the OEM tires last year. I don't know if the higher spring rate made the tires work harder or not, but after half a run they would start getting a little greasy. Four-wheel drifts were quite easy at that point. I've changed to MX's this year. Now the challenge will to get enough heat in them so they will work. I used 38f/36r with the OEMs and they never rolled over.

On second thought, maybe my driving style is more to blame for the four-wheel drifts. :p

09Factor

Hey Chops,
Something for ya. Sorry I didn't get a chance to meet you Sun.
Considering you posted on one of your runs a 94.xxx, thats good for B stock at PIR.
The Red 8 that was there (Pret) only posted a 97.xxx and he's a really aggressive driver .

I felt honored by watching your run..

Dave

09Factor

And some more...

pret

i found that @36, i was coming below the treadwear mark. higher front air pressure would keep you more on the treads. i always thought that a stiffer or larger diameter front sway bar would decrease the understeer inherent with this car. also, wouldn't stiffer springs also help with understeer and keep you in stock?neway, nice run! man ur fast! i guess i gotta be more agressive

E, did you get to meet Tim with the yellow FD? Hes our president of the rotary car club of AZ, RCCAZ. check out the website, RCCAZ.com.

09factor, thanks for the great pics! I did notice that you have more of the yellow then the red! haha

John V

iTrader: (1)

If your club follows SCCA rules, springs must remain stock.

I agree that a bigger front bar will probably help the car be faster in sweepers. Looking at some pics I have of Clyde's car, looks like he has about +1 degree of camber in the outside front wheel at full front compression in a hard corner. A front bar would eliminate body roll and help keep the camber in check.

Dark8

Are the results posted anywhere?

pret

www.azsolo2.com

ChopsMcgraw

Hey, Great Pics! Thanks for the compliment, but I want to try and catch that BS 350z so I've got a ways to go, especially since he has sticky rubber. I didn't get a chance to meet Tim, I was pretty much dead tired that day, had been at a music educators conference the 2 days prior so I bailed pretty early. I wish that I had brought air so I could fiddle with pressures, but I just kind of blanked it. I'm just looking forward to the next event, that site makes for pretty killer fun courses!


Chops
Base 6spd

Imp

Interesting classing... what are all those other ST1, ST2, etc.. classes under the PRO class?

I saw that Josh Sorter (Black WRX) is still running very fast and cleaning up in PAX. I ran against him at Nationals in my WRX this year. He was faster than me by .5 second on day one, but he didn't have a good wet run on the 2nd day. Don't get much rain down there to run in, do you?

Is it April yet? it's killing me to just see my car sitting out in the driveway.

--kC

Ike

They're street tire classes KC, we have em in Milwaukee as well and they get 50+ entries a week. Though we just have two classes for em.

Street Tire 1 (ST1)
Street Tire 1 is a local regional category for any driver using street tires in a car which would normally run in the SS, AS, BS, FS, ASP, BSP, ESP, SM, SM2, AP, BP, CP or any Modified Open classes. Each entrant in this category compete against each other based on their PAX handicapped time. The PAX handicap depends on the Open class that the vehicle would normally compete in.

Street Tire 2 (ST2)
Street Tire 2 is a local regional category for any driver using street tires in a car which would normally run in the CS, DS, ES, GS, or HS Open classes. Each entrant in this category compete against each other based on their PAX handicapped time. The PAX handicap depends on the Open class that the vehicle would normally compete in.

Street Tire 3 (ST3)
Street Tire 3 is a local regional category for any driver using street tires in a car which would normally run in the CSP, DSP, FSP, DP, EP or FP Open classes. Each entrant in this category compete against each other based on their PAX handicapped time. The PAX handicap depends on the Open class that the vehicle would normally compete in.