Quick help on Hoosiers, tire pressure for a/x Options

[Trekkor]

205/50/ZR15's R3S03's

I'm pushing. Help me turn in.

Ran 25psi front and 27 psi rear. How low can I go?

I'll loosen up the front bar as well. Workin' on tiars right now. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

Thanks, KT

[drew365]

Generally Hoosiers don't like to be run that low. I experimented with pressures from as low as 24# and found they would stick the best at 31# cold which is what they recommend in the pamphlet that comes with them from Tire Rack.
But that is on the track where I get them heated up after a lap. You're doing AX, you should be using the A series but I'm sure you know that. When I ran them as low as 24, 25 and 26# cold I felt like the side wall was starting to roll over.
So, I don't know what to tell you for R tires on AX but I still don't think you want to be running that low. I would try 29# to 31# range ambient temperature.

[nebreitling]

dood, forget the aircan for now -- put those springs in!

[Randal]

QUOTE

dood, forget the aircan for now -- put those springs in!

Well said.

I never got the Hoosiers to work unless I ran low pressures. Your ending point was my starting point, but I'd start with 26 in the rear and go down from there.

I'll call you tomorrow AM.

Cheers.

[Trekkor]

Thanks, Randal. That's what I was calling about.
Sounds like you have something up your sleeve (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif)

I ran the Hoosiers on a lonely hill at 26R and 24F. Felt more responsive to me. No evidence of rollover on the sidewalls. (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

Front bar is still unchanged. 150# rears still on.

KT

[drew365]

At those pressures you're relying on the rolling resistance of the flexing rubber for grip and not the chemical compound. I wouldn't try that on a track, but I guess you can get away with it at AX.

[Trekkor]

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif)
Good points. If I see any track time I'll get the pressures up.

You're the track boss at WCC, right? I'll need some help.

KT

[drew365]

Yup, if you come to WCC05 you'll like the track day. Streets of Willow is basically a large AX. You really have to work the car, hands and feet are moving all the time.

[campbellcj]

I suspect part of the issue is running the "R" Hoosiers for autox. You will probably never get enough heat into them to get normal Hoosier grip. The "A" version is compounded for autox and should heat up extremely quickly, although would be worthless on the track.

FWIW as Andy mentioned I typically run them in the 38-40psi hot range, which equates to 30-32 cold, plus or minus. Other -R tires like Kumhos seem to be happy with significantly lower pressures (<30psi), I guess due to the different belt/sidewall/compound construction.

[drgchapman]

I bought the "R" hoosiers last year. Best times last year with 28R, 26F. Stock sway bars, 140# rear springs, neg 2 degrees camber all four corners. Koni adjustables set on med-soft. Bested a GT-3 that day!

Buying "A" model this year.

Gary

[J P Stein]

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif)
With the tire pressures: cold
I ran R Hoosiers for a season. Took off 1-1.5 seconds with the
As out of the box.

Push? No shit?
AR bar is too big, rear springs are WAY too soft as a result. Toe of 0 to out 1/16 at both ends will help turn in at AX, but will screw you up everywhere else as it will be directionally unstable.....like an F-16.

Uh-oh, Gary is gettin' serious. I liked your "rough" tires mo better.....but you still ain't gonna catch me (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)
You can take the ulyf for a fun runs on 17 April & see why (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[SirAndy]

QUOTE (trekkor @ Mar 7 2005, 05:19 PM)

I'm pushing. Help me turn in. Ran 25psi front and 27 psi rear. How low can I go?

if it's pushing, try running MORE pressure in the rear. that should help yer ass to come around easier ...

(IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) Andy

[Series9]

QUOTE (trekkor @ Mar 7 2005, 06:19 PM)

I'll loosen up the front bar as well.

With that bar, I'm surprised it turns at all. (IMG:http://www.914world.com/bbs2/html/emoticons/cool.gif)

[J P Stein]

Dan Gurney.....one of my short list of heros, was one of the first/best of the big bar/ soft spring practioners.

He had purpose built race cars, with infinitely adjustable suspension, a truck fulla shox, springs, tires, LSD clutch packs, AR bars, alignment tools and a crew of guys that knew how to use em' all. He ran on billiard smooth (mostly) tracks and had 2-3 days to set up the car for a given track.......that he already knew. He was/is a suspension set-up guru....."fiddly" per some, but you can't knock his success.

About the only thing I can take from him in my endevors is his thinking of running the car as low as possible *without* running on the bump stops under "normal" (AX type) loads.

You can't adapt a car to your philosophy without designing the thing to it originally. You adapt your thinking to the car (IMO).

I wanna do AX. My venues are rough and kinda tight. I need suspension travel, but I want to keep off the bump stops...except on big bumps. I want the car to turn in quickly, neutral in mid corners with oversteer on command.....tight and sweepers.
I don't want the inside rear wheel to lift. I'd accept lifting the inside front lifting if all else was as I wanted. Big bars, little bar, no bars.....same with springs....don't mean shit to me as long as it all worked.