I think I am regretting my spring selection

cossie1600 · 12-10-2013, 03:39 PM

I ended up with 14k springs in the front. I am starting to regret it as I think it is too stiff, I probably should have gone with 12 and a big bar instead of 14. What do u guys think

GSS138 · 12-10-2013, 05:05 PM

Personally, yes. WO aero 14k is kinda stiff. The OEM setup has a wheel rate of about 167 in the front and 146 in the rear.That calculates out to a a ride frequency of about 1 with a 15% difference front/rear.

14K frontis 300+ wheel rate and a >=2.0 Hz ride frequency which is definitely above or at the upper limits of where a non aero sedan type car should be.

as a general guideline:
 0.5 - 1.5 Hz for passenger cars
 1.5 - 2.0 Hz for sedan racecars and moderate downforce formula cars
 3.0 - 5.0+ Hz for high downforce racecars

So unless you have a pretty significant splitter, you might want to tone it down.(Or buy a splitter!)

Check this link out
http://www.optimumg.com/docs/Springs...Tech_Tip_1.pdf

03threefiftyz · 12-10-2013, 06:11 PM

I violently disagree with the frequency guidelines above. You won't find a formula car with 1.5hz frequencies on planet earth. Most GT based race cars are 3hz+ and formula cars are over 4. 14k is not all that stiff in reality.

clintfocus · 12-10-2013, 08:05 PM

just curious, what about it seems "too stiff", also what dampers are you running?

GSS138 · 12-10-2013, 09:56 PM

Quote:

Originally Posted by 03threefiftyz

I violently disagree with the frequency guidelines above. You won't find a formula car with 1.5hz frequencies on planet earth. Most GT based race cars are 3hz+ and formula cars are over 4. 14k is not all that stiff in reality.

Formula 1 no. Formula 5000, probably. I don't have specs on either one nor am I friends with any drivers from either one. But without Aero, I can not see any reason to use anything stiffer than 14K on a road course that has bumps, camber, and traction changes.

In a nice flat Auto X environment I can see the point. 14K spring with a corner weight of ~800 lbs is pushing the limit of tire compliance and would only be good on a very smooth flat surface-like auto X or tarmac. You will not be getting enough bump travel to ensure tire compliance. I don't know the math on bump stop rubbers, but proper bump stops is probably a better answer than 18K springs whether on tarmac or corner 6 of Big Willow.

03threefiftyz · 12-10-2013, 10:03 PM

Sorry man, but you are WAY out of alignment with what actual race cars use...

Even FSAE cars are well above 4hz.

03threefiftyz · 12-10-2013, 10:07 PM

Also, while most of the West Coast Auto-x sites are pretty flat...it's the opposite on the right coast. Our sites are mostly bumpy as ****...

Case in point:

clintfocus · 12-10-2013, 10:21 PM

waiting for the rest of the car's suspension specs before i give some input.
but in my opinion, a 370 on wide front tires at a good pace, 14kg isnt outta the question, but the damper needs to be up to snuff

GSS138 · 12-10-2013, 10:22 PM

Well then I apologize on believing in basic math. A small note though, if your front right tire is 8+ inches off the ground, you suspension is probably not tuned right and you need to reduce your spring rate. TY for proving my point with your photo demonstrating a terrible suspension.

03threefiftyz · 12-10-2013, 10:37 PM

I find this bordering on hysterical, but do carry on...

..it is "jacked" up because he hit a bump at 50mph while accelerating out of constant radius corner.

Same corner:

03threefiftyz · 12-10-2013, 10:42 PM

Also, although I don't agree with Dennis Grant at all on set-up, he does supply an easy to use dynamics calculator on his website...

Autocross to Win (DGs Autocross Secrets) - Dynamics Calculator

03threefiftyz · 12-10-2013, 10:53 PM

Just out of curiosity, I looked up what a bog standard 996 GT3 cup car came with for springs....1200lb on front, with a strut.....on car with no weight on the front wheels. Then again, I am sure the fine folks at Porsche motorsport are just plain stupid and haven't discovered the internet knows all.

GSS138 · 12-10-2013, 10:54 PM

I'm just trying to think of that race where the winner had two wheels off the ground. Oh yeah now I remember, the Dukes of Hazard, those guys were fast! I bet they were using like 5000Hz wheel rates to get away from Boss Hog!

03threefiftyz · 12-10-2013, 10:58 PM

Quote:

Originally Posted by GSS138

I'm just trying to think of that race where the winner had two wheels off the ground. Oh yeah now I remember, the Dukes of Hazard, those guys were fast! I bet they were using like 5000Hz wheel rates to get away from Boss Hog!

You must not watch any touring car racing....

GSS138 · 12-10-2013, 11:00 PM

Umm that's not a touring track on television, that's a parking lot with cones.

12-10-2013, 03:39 PM	#1 (permalink)
cossie1600 A True Z Fanatic Join Date: Jun 2009 Location: californee way Posts: 5,380 Drives: 370, Leaf Rep Power: 30	I think I am regretting my spring selection I ended up with 14k springs in the front. I am starting to regret it as I think it is too stiff, I probably should have gone with 12 and a big bar instead of 14. What do u guys think

12-10-2013, 05:05 PM	#2 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	Personally, yes. WO aero 14k is kinda stiff. The OEM setup has a wheel rate of about 167 in the front and 146 in the rear.That calculates out to a a ride frequency of about 1 with a 15% difference front/rear. 14K frontis 300+ wheel rate and a >=2.0 Hz ride frequency which is definitely above or at the upper limits of where a non aero sedan type car should be. as a general guideline:  0.5 - 1.5 Hz for passenger cars  1.5 - 2.0 Hz for sedan racecars and moderate downforce formula cars  3.0 - 5.0+ Hz for high downforce racecars So unless you have a pretty significant splitter, you might want to tone it down.(Or buy a splitter!) Check this link out http://www.optimumg.com/docs/Springs...Tech_Tip_1.pdf __________________ Current Mods: Vorpal Weapon +5.

12-10-2013, 10:22 PM	#9 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	Well then I apologize on believing in basic math. A small note though, if your front right tire is 8+ inches off the ground, you suspension is probably not tuned right and you need to reduce your spring rate. TY for proving my point with your photo demonstrating a terrible suspension. __________________ Current Mods: Vorpal Weapon +5.

12-10-2013, 10:37 PM	#10 (permalink)
03threefiftyz Track Member Join Date: Apr 2010 Location: MD Posts: 536 Drives: 03 350z 6mt Rep Power: 16	I find this bordering on hysterical, but do carry on... ..it is "jacked" up because he hit a bump at 50mph while accelerating out of constant radius corner. Same corner: 2004YZFR1 likes this. Last edited by 03threefiftyz; 12-10-2013 at 10:39 PM.

12-10-2013, 10:54 PM	#13 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	I'm just trying to think of that race where the winner had two wheels off the ground. Oh yeah now I remember, the Dukes of Hazard, those guys were fast! I bet they were using like 5000Hz wheel rates to get away from Boss Hog! __________________ Current Mods: Vorpal Weapon +5.

12-10-2013, 06:11 PM	#3 (permalink)
03threefiftyz Track Member Join Date: Apr 2010 Location: MD Posts: 536 Drives: 03 350z 6mt Rep Power: 16	I violently disagree with the frequency guidelines above. You won't find a formula car with 1.5hz frequencies on planet earth. Most GT based race cars are 3hz+ and formula cars are over 4. 14k is not all that stiff in reality.

12-10-2013, 08:05 PM	#4 (permalink)
clintfocus Track Member Join Date: Jan 2011 Location: los angeles Age: 39 Posts: 933 Drives: 370z, EK Civic, F150 Rep Power: 16	just curious, what about it seems "too stiff", also what dampers are you running?

12-10-2013, 10:03 PM	#6 (permalink)
03threefiftyz Track Member Join Date: Apr 2010 Location: MD Posts: 536 Drives: 03 350z 6mt Rep Power: 16	Sorry man, but you are WAY out of alignment with what actual race cars use... Even FSAE cars are well above 4hz.

12-10-2013, 10:07 PM	#7 (permalink)
03threefiftyz Track Member Join Date: Apr 2010 Location: MD Posts: 536 Drives: 03 350z 6mt Rep Power: 16	Also, while most of the West Coast Auto-x sites are pretty flat...it's the opposite on the right coast. Our sites are mostly bumpy as ****... Case in point:

12-10-2013, 10:21 PM	#8 (permalink)
clintfocus Track Member Join Date: Jan 2011 Location: los angeles Age: 39 Posts: 933 Drives: 370z, EK Civic, F150 Rep Power: 16	waiting for the rest of the car's suspension specs before i give some input. but in my opinion, a 370 on wide front tires at a good pace, 14kg isnt outta the question, but the damper needs to be up to snuff

12-10-2013, 10:42 PM	#11 (permalink)
03threefiftyz Track Member Join Date: Apr 2010 Location: MD Posts: 536 Drives: 03 350z 6mt Rep Power: 16	Also, although I don't agree with Dennis Grant at all on set-up, he does supply an easy to use dynamics calculator on his website... Autocross to Win (DGs Autocross Secrets) - Dynamics Calculator

12-10-2013, 10:53 PM	#12 (permalink)
03threefiftyz Track Member Join Date: Apr 2010 Location: MD Posts: 536 Drives: 03 350z 6mt Rep Power: 16	Just out of curiosity, I looked up what a bog standard 996 GT3 cup car came with for springs....1200lb on front, with a strut.....on car with no weight on the front wheels. Then again, I am sure the fine folks at Porsche motorsport are just plain stupid and haven't discovered the internet knows all.

12-10-2013, 11:00 PM	#15 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	Umm that's not a touring track on television, that's a parking lot with cones. __________________ Current Mods: Vorpal Weapon +5.

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