laze1

iTrader: (17)

Should I use early or late REAR springs for NASA TTC?

Ok, so I am now engineering my car to run in NASA Time Trials...that is why I ask.

I am currently running a 2006 Grand Touring w/stock shocks, Hotchkis TVS, and SPL F & R camber arms, w 17x10 wheels and 275-40-17 RA1s . Also, I run my sways bars full soft in the rear, one hole up from full soft in the front. I bought all this stuff for HPDE, but now moving to TT.

But this setup moves me from TTC*(+7 points base) base class to TTB (total of 24 points over base class of TTC). So if I go back to stock springs and 255-40-17 tires I can run TTC...So I have of choice of using the early rear springs or "revised" new rear springs.....not sure which one to run??

I really like the Hotchkis setup, very nice and neutral, with just a hint of oversteer when running the "square wheel/tires" setup, very little understeer with the stock 18/19 wheel combo...and I would like to keep that.

So should I use the early springs? (still using the Hotchkis sway bars and square setup)


Oem springs 350Z’s 2003/2004
Front:314 Rear:342

Oem springs 350Z 2004.5/2005 (this is what come on the car new)
Front:314 Rear:427

Hotchkis Linear springs .6”/.8” drop (this is what is on the car today)
Front: 340 Rear 330
Stiffer or softer then oem springs by F+8% R-3% (relative to the early version spring rate)

terrasmak

iTrader: (8)

I would run the stock late model springs, they are better rates for your shocks.

Fooshe

iTrader: (42)

agree...late model springs.

Fluid1

iTrader: (19)

Can you list out all of your mods and corresponding points? Thanks,

laze1

iTrader: (17)

350Z Grand Touring is in TTC base class, with 7 points penalty added (TTC*)

So I start with TTC
add 7 points for the (*) Grand Touring Penalty
add 5 points for the Toyo RA1
add 4 points for 20MM over the base class tires size of 255 MM ( I run 275)
add 2 points for non-OEM springs
add 2 points for non-OEM sway bars
add 4 points for non-OEM upper control arms

Total points 24

You move up a class for every 20 points

http://www.nasaproracing.com/rules/T...ation-form.pdf

laze1

iTrader: (17)

My other option is to go with larger and stickier tires. Like 295 tires (rear only) like the Hankook Z214 or Kumho 710) and use up as many point that I can and stay in TTB...

BTW: If I re-install my stock springs, I can run both classes by just changing wheels/tire combos....I have a set of 4x 17x10 and 4x 17x9.5 wheels...This is a very good option so that I can run in the class that benefits me the most on a given weekend.

TIRES:
1) DOT-approved R-compound tires with a UTQG treadwear rating of 40 or less (ex. BFG R1, Hankook Z214,
Hoosier R6 & A6, Kumho V710, etc.—note: G.A. Cup Hoosiers OK) +10
2) DOT-approved R-compound tires with a UTQG treadwear rating of 50 to 130 (ex. Kumho V700,
Michelin Pilot Sport Cup, Nitto NT01, Pirelli PZero Corsa, Toyo R888, Yokahama A048, etc.—
note: see exception below in 3)) +7
3) Toyo RA-1 and Nitto NT555RII +5
4) Non-DOT-approved racing slicks +30 (of an origin—re-caps and re-treads are not permitted)
5) The following tire sizes will be used as the base tire size for each Base Class for all vehicles regardless of their OEM tire
size(s). All vehicles in a given base class may use this tire size (or smaller) without a points assessment:
TTA: 295 mm, TTB: 265mm, TTC: 255mm, TTD: 245mm, TTE: 235mm, TTF: 215mm, TTG: 195mm, TTH: 175mm
Increased tire width beyond that listed above (using the largest increase of front or rear if using split sizes) will be
assessed as follows:
Equal to or greater than: 10mm +1, 20mm +4, 30mm +7, 40mm +10, 50mm +13, 60mm +16, 70mm +19,
80mm +22, 90mm +25, 100mm +28, 110mm +31, 120mm +34, etc.

Fluid1

iTrader: (19)

Larger and stickier tires are useless if you don't have the camber to put the full surface on the ground.

Fluid1

iTrader: (19)

Get rid of the non-OEM swaybars -2
Switch the springs to Swift (still same points)
Get rid of the non-OEM upper control arms -4
Koni Yellow shocks valvematched to the Swift springs +3
Run 255 tires instead of 275 -2

Grand Total: TTC +19

laze1

iTrader: (17)

I run 3+ deg front, 2 deg rear now.....

I have SPL front and rear adjustable camber arms...

I can't image running the z with some big camber in front

Fluid1

iTrader: (19)

This makes no sense to me. Please rephrase.

I'm sure you don't run positive camber. So I assume you mean you currently run -3 degrees in front. "I can't image running the z with some big camber...."

-3 IS big negative camber. What is 'big' to you? -5*?

Fluid1

iTrader: (19)

Maybe you missed this.

betamotorsports

iTrader: (1)

I strongly suggest using a pyrometer to determine the camber needed for the 350Z. Just because folks in other cars run camber numbers of -3 or more doesn't mean its right for the 350Z. The front of the 350Z gains about 1.5 degrees of negative camber in bump with 2" of bump travel. There is also some negative camber gain in bump from the 9+ degrees of caster (about .5 degrees). Combining the suspension and caster camber gain my guess is the car has about 65% camber recovery in roll which means it requires less static negative camber to start with. Some of my testing with a pyrometer confirms this.

But, a lot has to do with tire selection so that's why its important to test on your own car and setup.

laze1

iTrader: (17)

I saw it,,,thnx for the input!

laze1

iTrader: (17)

Duh,,,sorry..

I should have said: I run 3 Plus deg of negative camber (3.2 L & R)

I think "big camber" is 3 Plus deg of negative camber..

also I mis-typed again when I should have said "I can't image running the z without big camber",,,,,

But I obviously am not an Engineer, I just know what feels good to me and gives good even tire wear on track days....I don't have a pyrometer and other nice-to-have tools like that...I'm just a guy out to have fun...and occasionally pass somebody and put done some reasonably quick lap times


I am mainly working on the "Driver"!

Fluid1

iTrader: (19)

Based on your other thread, it seems as you have a setup in mind. I'm glad, hopefully we can attend the same events in TTC and compare setups and lap times.

laze1

iTrader: (17)

I am just "thinking" about setups, learning all the way..( and using what I have in stock)

all these discussions have been very helpful in my "race track setup" learning process!

racing on a very limited budget SUX.....but make you be creative.

Thnx for all the input everybody.....

Fluid1

iTrader: (19)

Let me know what events you plan on attending this year and next, we'll have to get up and race.

laze1

iTrader: (17)

Come on down South....

Next event for me is Roebling Rd/Savannah GA
Florida Crown Region PCA HPDE - Sept 13th & 14

I am a PCA Instructor, and will have my son as a student with me for his 3rd track day...and I hope to try out my new setup..whatever that is

I have run Roebling many times, so it is a good test track for me as I have a good baseline to work from

Fluid1

iTrader: (19)

I live in Charlotte, NC.

Unfortunately I will be in New York that weekend of September 12-14

laze1

iTrader: (17)

How about Road Atlanta - NASA event Aug 9/10???

I will not be driving in this event..just volunteering with the TT and Enduro Directors.....I hope this helps me get my W2W comp license..i.e. suck-up big time before I ask for the license...