cwalker

iTrader: (4)

Does anyone have any B Stock performance or tuning tweaks that they would be willing to share?

I am an experienced A/X'er, but have no exerience with my recently purchased '03 Track model.

I read that it pushes in the corners, but this can be balanced by matching tires on the 4 corners. Anything else that is BS legal.

chubmann

I have high speed a/x my '03 Touring model in B stock at Blackhawk Farms. You are correct that it pushes in corners and was able to tune some out with tire pressure. I am going to try even higher pressures in the rear (which inreases the spring rate). This is not the optimal because you are meant to stick the unstuck end but I feel that giving the back end a little bit of a nudge to come around will help. Also found that it needs the high temp brake fluid (like Wilwood 550).

cwalker

iTrader: (4)

What tire set-up are you running? Do you have the same width tires in front and back or are they staggared?

I'm running Mich Sport A/S's, 225 fronts and 245 rears, non-racing of course. I played with the tire pressures from around 30-45 psi in efforts to get them to corner better on the street. I noticed that with these low profile tires (35's front - 40's rear) that the car would push even more if I went above 35 psi, but would actually stick better around 33psi... The pushing was horrible up at 45psi, on the fronts. I kept pressure the same front to rear when testing this. However, I did also notice that it was harder to spin the rear tires, while launching, at around 38 psi.

I think this pushing of the fronts at higher pressures is due to the contact patch dimenishing because the tire actually crowns, or becomes more rounded.

You may be able to increase the grip in the front by reducing the tire pressure on the front tires... asuming you can run any lower than you already are. -just a thought

I'd be interested to know what tires/pressures racers are running.

tomsn16

iTrader: (2)

Suggest following for BS:

Shocks.............Koni SA or DA
Sway Bar.........Needs to be 20-40% stiffer,we use a 32mm solid bar,there are many options.
Alignment........Front Toe=1/8"out(total),Rear Toe=1/4"in(total)
Tires................275/40/17 or 275/35/18 .Tire press at 44F,40R.
Wheels...........light weight as you can find and afford.Rays are good if you have a Track.

tomsn16

iTrader: (2)

Tire pressures are for Hoosier 275's. For the Kumho 275/40/17(there is no Kumho 275/35/18 yet) the pressures will be much lower...like 30/26.

cwalker

iTrader: (4)

tomsn16 - How's the pushing problem with your setup? Did you add your components progressively or all at once?

I was wondering which part of this setup reduces pushing the most?

soloracer

tomsn16 (Carter) - do you still have your Z? If not, what are you competing in? I heard lots of stories & cars. Did you know Mike King is running a older M3 (E36) model to compete in BS? However, I have heard that he was also running a Miata? Came real close to Ian a couple of weeks ago at Gulf Coast in Ft. Myers. They had a 2-day event & Ian was in a GT-3. The Saturday course was really fast with long sweepers. I was about 2 sec behind him. Not bad for a fat pig Z against a $125K rocket Porsche. Are u going to Jax in March?

tomsn16

iTrader: (2)

CWALKER...regarding push.With our car push was not a problem.The Hoosier 275's plus alignment(which is not far from stock)were probably the biggest factors. The shocks and big frt sway bar are needed to keep rear wheels down on corner entry and exit...to use the Z's torgue you have to do all possible to keep those rear wheels down to put the power down.

SOLORACER....Sounds like you did very very well to stay close to Ian(no matter what he was driving).We have an '05 Track ordered for the BS wars this year.Won't be in Jax but have a Z codrive planned for Ark Tour,Atl Tour and Atl Pro. Don't expect our Track to arrive until May or June.

larson

iTrader: (1)

Is there any problem with mounting the 275-40-17 to the stock 7 1/2 inch front rim? Recently purchased an enthus and have purchased another set of stock rims for kumho's. Thanks for info already posted it's extremely helpfull.

tomsn16

iTrader: (2)

No problem with 275/40/17 on 7.5 rims. It is the right tire size for the Z. Remember the Kumho 710's like low pressures.

PDX_Racer

iTrader: (2)

Thanks for the setup suggestions!

del105

iTrader: (4)

I suggest going somewhere that is patient and good at mounting tires. Having some highschool kid trying to mount a 275 on a 7.5" wheel is probably a good recipe for some scratched up wheels.

cwalker

iTrader: (4)

tom - is there a rear wheel lifting problem on the Track model? I was doing a little research on the Koni's and read that the Track has a stiffer suspension than the other models.

Do you have any experience with this?

tomsn16

iTrader: (2)

My info on spring rates is that all models are same for a given year. I believe the 03's have 314 #/in front and 342 rear. The '04 models have same front but 425 rear. Don't have any info for '05 and in anyone has corrections to these specs please holler.
However,for SCCA BS you have to run the OEM springs that came on car ,you cannot change them.

chubmann

I think the original thought was to get the most out of a B stock configuration. Where I run, any of the additions that were mentioned would bump you to B modified which is still an ok place to run. As to using the car as stock, stickier tires may help. When it comes to pressures, they more effect the spring rate at that corner than the contact patch. The pressure would have to be much higher (like 60-80 psi) to get any noticeable crowning with a steel belted tire. This is a correct assumption with real racing tires that don't use as stiff of a contruction. I was running 38 psi LF, 35 RF, 34 LR and 34 RR. This had to much spring rate on the LF and caused the car to push on the predominately right hand turn circuit of Balckhawk Farms. Next time I will go lower (like 32 psi) in the left front with 38-40 psi left rear. Also this car may respond to a different (i.e. later turn-in) to get the back end to loosen up.

Good luck to all.

hippie

iTrader: (9)

Tomsn16...When I rated the springs in my '03 track I came up with 309 frt, 350 rear...close enough. I have two questions though. Couldn't I run the rear springs from a '04 track in a '03 track since they are the same model. I know I can't match rim sizes frt and rear since that is from a different model/ package, but the springs are both in track models. I didn't know the '04 was stiffer.
Normally I run 245/35/18 Hoosiers, but I tried running a set of 275/35/18's. To get any response out of the tire and to keep from wearing through the sidewalls I ended up with signifigantly higher pressures than you recomend, 60 frt 52rear. I assume the lower pressures help grip, but how long do the tires last?

bar- Hotchkis set med or stiff
shocks-frt stock(for now)
rear Ohlins
alignment-1/16 out frt 1/8 in rear

Hippie

tomsn16

iTrader: (2)

hIPPIE
1. In SCCA stock classes backdating is not allowed so you cannot use parts from another year if they are different from your year.
2.I am suprized that the 275's did not solve most Z handling problems.Your Hotchkis bar is stiffer than stock so your setup is very close to ours....EXCEPT for the Koni's. Could be that our Koni DA's are doing more than I thought. Also,we typically run the Koni's at near full stiff rebound and midrange to high bump (depending on how smooth surface is).When the car is stiff enough two wonderful things happen.1) you can throttle steer when you want to(no push) and 2) you can put the power down out of corners(no inside wheel spin).
60/52 psi with Hoosier A3S04's is much to high. We typically ran 44/41 down to 41/38 . Most similar weight cars run Hoosiers in low 40's to high 30's.
We got exceptional tire wear with the 275's. Best autoX car we have ever had in this respect. We got 80-100 runs with very uniform wear pattern...no flat spotting...when cord finally showed it was on outside edge as you would expect.In all cases we moved tires front to rear at about 50 runs.Grip was always best 0-40 runs but we found it to stay good until cord.
My guess is you need Koni's.

tomsn16

iTrader: (2)

Hippie....I just noticed that you have OEM front shocks and Ohlins on rear. I assume the Ohlins are stiffer than OEM rears and if so this may explain your very high tire pressure.
With SCCA stock class rules what we basically do is stiffen and stabilize the FRONT with bigger sway bar and higher rebound/bump shocks to make the car handle. In your case you have the best shocks on the wrong end of the car. When you get Ohlins or Konis on all four corners handling should be much much better.

cwalker

iTrader: (4)

tomsn16 - Cost aside, which upgrade (aside from tires) should I do first... Koni's or front sway(Brand suggestion)? What makes the most difference on the a/x track?

Anyone else have input on this?

tomsn16

iTrader: (2)

To make the Z fast you need all three. For sure the Koni's and bigger sway bar should be done together.