FC with JIC FLTA2s - 8kgF, 6kgR, stock sway bars, PU bushings, dtss disabled, front roll center spacers, alignment - -2.4F/2.6R camber, 1/32F 3/32R toe in. Vehicle weight is 2520 with 11 gallons of fuel with no driver, vehicle balance with driver and above fuel is 50/50 front to rear balance, 50/50 cross weights and 50.5/49.5 left to right balance. 17x8F 17x9R with 235/40/17s Toyo RA1s all around, auto power 4 pt. Power is approx 290whp @ 14.5psi.

Drove the car at a Solo 2 practice this last weekend detuned to approx 165whp and everything felt perfect. The suspension reaction is entirely predictable and entirely neutral, transitioning exactly how you want it. Was at the NASA event @ Button Willow in HDPE 3 and had mechanical problems so had to opt into HDPE 2. It was brake fade. Partly due to fluid i shouldve changed but I've never experienced brake fade at this track or any other event. However it was my first time running R compounds at Button Willow.

So basically, my question is where to go from here. The car is how I want it now, just want more grip and more power. I think I will try to shoot for 255s on all four corners and increase power but is there anything larger holding me back which can be addressed such as FC suspension pick up points, control arms, ASB, chassis flex, steering angles, bump steer, etc.

Any constructive and insightful advice is appreciate. I know theres a lot of variables involved so if theres anything left uncovered please ask. Thanks in advance.

 

Looks like you have everything covered with equipment on the car. Now getting everything to work together is the trick. You have every adjustable part so I would invest in a pyrometer if you don't have one. That will tell you if your settings are right for the track. From the quality of your parts selection I'm guessing this isn't your first rodeo, if you know what I mean.
Beyond a pyrometer and getting split times I'm guessing more seat time in the car is going to give you the most improvement.
You mentioned brake issues, get some cooling air to those fronts and get some racing fluid, I like Motul but it sucks up moisture and needs to bled a lot.
Improving suspension geometry is beyond what I can offer over the forum without knowing your ride heights etc. and what you are capable of fabricating. There are some things you can do with subframe bushings in the rear(raise it) but then you have to get the drive line back in phase.
One more thing, we all want more power and grip and braking!

 

If you call me, we can cover it in detail. Try me on a saturday, or sunday afternoon. Stock brakes with Carbotech XP9, or 10 and ducting works on my car, it will surely work on yours. I use the Motul 600(12.95/pint), XP10 pads, stainless lines, and a stock sytem otherwise. I will be adding a recirculating system this winter. Maybe you are on the brakes too much. I'll be instructing at Thunderhill Oct. 29-30. I know its quite far, but it is a very fun track. I actually did not even have ducting until my last event. As far as going faster, you need seat time first. The toe in the rear S/B 0 IMHO, the front S/B slightly out(1/8). What pressure, and tire temps did you see? Hot/cold etc. Was the car loose, tight. At the limit does it understeer, or oversteer? If you say it's nuetral, you are probably not going fast enough. Do you left foot brake? Like you said there are alot of variables. What tires are you running? I would just switch to a 255 in the back, otherwise you will need new wheels, and front fenders. You are no where near the limit yet for your set-up. What are your spring rates in lbs? they should be around 275/450 for a dual use car. I would set the JICs full stiff in front, and about 50% out back to start. What are your oil, and water temps, and where are you measuring them? Anyway, first thing is to max out your system. Your car could run in group 4, so that means set-up(tire pressures/alignment/sway bar settings, spring rates), and you are the two things to work on right now. You may have too much rear camber as well. When my FC was 2900lbs, and made 290rwhp, I was in the top 2, or 3 in group 4 in norcal as far as dual use cars. That was on 235-40-17 RA1s with 275/450, and RB sways set full stiff up front, and the lighter setting in the rear. Call me this weekend, but make some notes first so we don't go off on a tangent. Later, Carl

 

Carl thanks a lot for the help, I'll try to post some feedback on here and more when I call you. It would've been nice if you had a ride or drove but I know you were busy giving your car a shakedown on that track. Thanks again.

 

removeeee the rear sway bar......

sorry but this will haunt you wherever u go for making me lose 2 hour of sleep !

 

you could run 16" wheels, like 16x9 CCW's with a 275 or 265 or 255 at all four corners to shed some pounds and get lower to the ground.
the wider tires would help you reach higher levels of grip, but how are you doing for brake pads? they will have a significant effect on lap times.

also a lexan rear hatch even a lexan windshield to lose more weight.

sounds like a badass FC.

 

Right, since this event, its helped me realize what needs to be revised and what needs to be completely redone on the FC. I was just panicing that I was hitting the upper limits of the FC but im obviously far from.

As for the braking, i've decided to go with the AWR ducts in the future with the hoses extending to the stock S5 bumpers side openings to help with cooling.


Carl this is Zubair and again id like to thank you for your help and feedback this weekend. It would've been nice to get a firsthand insight from you but you were clearly busy dealing with some of your own issues so hopefully we can catch each other another time. I wish I had the full range of information you need but unfortunetly, some of my metering devices were down/ missing the equipment to make proper measurements.

As for springs, I believe its approx 450lbsF and 370R. When I say its neutral its in the sense that it'd depend on the corner whether it'd want to oversteer or understeer at the limit. Through the tighter corners it'd be a slight understeer sensation that could be corrected with a bit of throttle while at higher speed it was slight oversteer. Tires felt excellent until the 3rd and 4th session when they felt they'd begun greasing up and giving up grip. unfortunetly without a pyrometer i was unable to get temps at that point. Water temps hit a peak of 87C.

As for wheel and tire sizing, I want to go with 255's on all four corners in the future using 17x9s.

Alpine, as you stated, the removal of the rear ASB is something thats been suggested to me a few times but I see such a wide range of opinions on it ranging from complete removal of it to thicker rear bars that im unsure of which direction to go in. Also as for the JICs, I'd like to speak with them because there was a bit too much roll through certain corners, I'd like to find whether increasing spring rates now that Im using r compounds primarily will help.

Thanks again for the suggestions. Heres some quick pictures from the event, you'll have to copy and paste for it to work, enjoy!


http://www26.brinkster.com/vertexspirit/IMG_4893.JPG

http://www26.brinkster.com/vertexspirit/IMG_4895.JPG

http://www26.brinkster.com/vertexspirit/IMG_4942.JPG

http://www26.brinkster.com/vertexspirit/IMG_4969.JPG

http://www26.brinkster.com/vertexspirit/IMG_4988.JPG

 

What are "front roll center spacers"?

 

Spacers that shim the tie rod attach points to the hubs.
These are popular with AE86's and S13's / S14's.
They are usually primarily to minimize bump steer on extremely lowered vehicles.
They are practically useless on stock height vehicles.


-Ted

 

Oh so they're bump steer correctors, and actually do nothing to the roll center.

 

No they do raise the front roll center.

 

How?
The only way I know of to raise the roll center on a strut suspension is to:
Lower the outboard attachement point of the lower control arm.
Raise the inboard attachement point of the lower control arm.
Or change the angle of the strut to more vertical.

 

I don't use only shims but you are correct. They lower the outer ball joint in relation to the spindle. There are other pieces from the stock car guys that do the same thing and use shims. Check out these http://www.colemanracing.com/catalog...?cPath=49_1276 They are used with monoball type joints and allow height adjustment of the outer ball joint.