my suspension is set up quite nicely right now (for my preferences), i would like a stiffer spring rate, but until i can afford coilovers, i was wondering what setting my hotchkis sways on stiffest/stiffest will do to my handling.

i'm currently on med/med. my springs are tein h tech for the sedan, soft, 320/270 approx.

-phil

 

phil,
with the springs you have on there right now, you have effectively reduced your rear roll stiffness, by 25% (or pushed 25% to the front). this will increase understeer. ignoring the sways for now.

with the sways at med/med like you have them, the roll stiffness has increased 60% to the rear (92% - 32%). the net roll stiffness increase would be 35% to the rear (60% to the rear from the sways minus 25% to the front from the springs). that seems like a lot, and i would think that it would produce some oversteer. i don't think it is a good idea to correct bad spring rates with your sway bars.

if you were to run them at full stiff, your roll stiffness would increase from 60% to 83%, and your net roll stiffness would be 58%. that seems a bit dangerous.

if you ran the front at full stiff, and the rear at medium, your net overall shift would be 4% to the rear. at that point, you might as well have saved the money on springs and sways.

i would leave them where they are at, or get new springs that are stiffer in the rear, and run full stiff front, and medium rear on the sways.

you can effectively ignore the effects from your tires, since they are almost the same width, front and rear.

i have hks ls+ coilovers and hotchkis sways on full stiff front, and medium rear. i will spare you the math, but it has produced a 1% shift to the front, and the car feels perfectly balanced. if i really get on it (like to the point of breaking traction) there is a tiny hint of understeer. which is what i want, when i am at the limit of the tires.

Chad

 

Excellent post chad, though I would not take the front to full stiff.

And I can offer him a easy solution for the rear spring rates. I have a pair of rear oem 350Z springs I have no use for. His Tein's drop the sedan 1.4" front and 0.7" rear. If he were to swap in the rear oem Z springs he's fix the rear spring rate and the overall drop would go to 1.4"/1.0". PM me if your interested AznIceRckt.

 

that is a great solution. linear springs. i like it.

however, if he did this, his rear roll stiffness would go up (since the stock Z springs are stiffer) and the oversteering element would increase. i think by taking the front to full stiff, it balances things out nicely. that is the beauty of adjustable sways, though, he can try out many different possibilities.

Chad

 

thanks for the tips guys.

i'll let you know about the oem springs, i believe i'll probably be picking up a set of coilovers soon though.

-phil

 

Doh, I honestly didn't think that my reply got posted as my computer froze up on the post. I actually gave the springs away to another forum member that needed them. Sorry about that.

 

Running the rear oem 350Z springs would bring back the 22% deficit the tein rear spirngs caused. Then tune the sway bars accordingly confirming with 4 corner tire temps. Spring rate tunning should always be the first route, then fine tune what's left with adjustable bars.

Going too high with sway bar settings will hinder a suspension's ability to act independently, not a good thing.

 

Here's a list of coilover specs, watch out for high spirng rates and large transfers of roll stiffness to the front.

Tein Flex (twin tube construction, adjustable dampners
Full-length adjustment and height adjustment for separate setting of the height and spring preload
Spring rates 672/672
Stiffer then oem by F+114% R+98
Transfers +16% roll stiffness to front
Side Note: Extremely high spring rates mean even when the adjustable damping is set as low as possible, you may not find ride quality happiness, several reports of this setups harshness exist Yet a few owner comment’s of a “like stock ride quality” also exist. However given the fact that they use a spring stiffness that’s over 100% stiffer then oem, if ride quality is of concern, either hitch a ride in a car equipped with them or make a different choice. In addition, several review’s have been done by people actually having the original more softly sprung Tein Flex coilovers do not take their comments to mean the same as the one using the current product, the original product specs are listed below under Tein Flex JDM.

Tein Flex JDM specs (can be special ordered est 6-8 weeks delivery)
Full-length adjustment and height adjustment for separate setting of the height and spring preload
Spring rates 560/560
Stiffer then oem by F+78% R+64%
Transfers 14% roll stiffness to front
Side Note: This is the original specs first offered in the U.S. with the Flex, shortly after it’s introduction the specs changed to those listed further above (672/672)


Tein Basic (twin tube construction, non adjustable dampners )
Spring rates 504/504
Stiffer then oem by F+61% R+43%
Transfers +18% roll stiffness to front
Side Note: Excellent value at it’s price point

Tein SS (twin tube construction, adjustable dampners )
(JDM only at this time. 6-8 weeks delivery, come via ship)
Spring rates 392/314-392 (rear’s are progressive)
Stiffer then oem by F+25% R+15% at peak



Tein CS (Monotube constructionad, adjustable dampners )
Special Note: A comfort ride system compare to HKS LS.They are valved and sprung to fullfill their intended mission of offering up improved ride comfort. More specifically their valving will impact the performance they can deliver. And to add, revalving them is extreamly expensive if you find they are too soft for you. If you want performance, pick a different Tein offering or pick a different brand.
Spring rates 392/392
Stiffer then oem by F+25% R15%
Transfers +10% roll stiffness to front




Nismo S-tune (twin tube construction, uses progressive springs, especially in rear)
350Z/G35 Coupe
Spring rates 448/504
Stiffer then oem by F+43% R+48%
Transfers +5% roll stiffness to rear




Nismo S-tune (twin tube construction, uses progressive springs, )
G35 Sedan
Spring rates 347/342
Stiffer then oem by F+10% R+0%
Transfers 10% roll stiffness to front

Buddy Club Racing Spec coilovers (Monotube construction, adjustable dampning)
Full-length adjustment and height adjustment for separate setting of the height and spring preload
748/336 to 672 + 280 on dampner
This setup runs 336~672 progressive rate spring at the stock spring location and a 280lbs linear spring on the rear dampner body. Since those differing rear spring locations leverage differing forces to the wheel, here is a look at the setups wheel rates as a percentage of stiffness over oem wheel rates.
Stiffer then oem by F:+238% R: +233% to 331%


Jic Flta-2 350Z fitment (Monotube construction, adjustable dampning)
Full-length adjustment and height adjustment for separate setting of the height and spring preload
Special Note: This setup is known for it’s street ride harshness, but also for track performance
Spring rates560/672
Stiffer then oem by F+78% R+98%
Transfers +20% roll stiffness to rear

Jic Flta-2 G35 coupe (Monotube, adjustable dampning)
Full-length adjustment and height adjustment for separate setting of the height and spring preload
Spring rates 560/560
Stiffer then oem by F+78% R+64% $1750
Transfers 14% roll stiffness to front

Jic Flta-2 G35 sedan (Monotube, adjustable dampning)
Full-length adjustment and height adjustment for separate setting of the height and spring preload
Spring rates 504/392
Stiffer then oem by F+61% R+15%
Transfers +46% roll stiffness to front

Cusco Zero 1&2 (Monotube Zero1=non adjustable dampner, Zero2=adjustable dampner)
Full-length adjustment and height adjustment for separate setting of the height and spring preload
Spring rates 560/392
Stiffer then oem by F+78% R+15%
Transfers +63% roll stiffness to front (no they do not run their rear springs on the dampner body, oem location, seen them on the car with my own eyes.)
Side Note: Thats a awful lot of spring stiffness to move to the front

(Offical word from Bilstein is that all PSS and PSS9 coilovers are on hold pending a redesign of the rear height adjustment system)

Bilstein PSS coil over (Monotube construction, non adjustable dampners)
Special Note: Mild spring rates, but Bilstein says the dampners are performance valved
Spring rates 370/240-420 (rear progressive)
Stiffer then oem by F +18% R +23% (at peak rear spring rate)
Transfers +5% roll stiffness to rear

Bilstein PSS9 coilover (Monotube construction, adjustable dampners)
Special Note: Mild spring rates, but Bilstein says the dampners are performance valved
Spring rates 370/240-420 (rear progressive)
Stiffer then oem by F +18% R +23% (at peak rear spring rate)
Transfers +5% roll stiffness to rear




HKS LS+ G35 Coupe (Monotube construction, adjustable dampners)
Spring rates 504/448
Stiffer then oem by F+58% R+29% (rear springs are progressive)
transfers 29% roll stiffness to the front
Side Note: Has the unusual distiction of actually being valved stiffer then the same coilover made for the 350Z, though the Z version does NOT transfer as much roll stiffness to the front

HKS LS+ 350Z (Monotube construction, adjustable dampners)
Spring rates 448/448
Stiffer then oem by F +43% R +31%
transfers 12% roll stiffness to the front
Sidenote: Listed on HKS's Japan web site, but not on the US web site. These might actually be our RS coilover.

HKS LS G35 (Monotube construction, non adjustable dampners)
Spring rates 448/336
Stiffer then oem by F+43% R -1%
transfers 44% roll stiffness to the front
Special Note: A comfort ride system, compare to Tein CS coilover

HKS LS 350z (Monotube construction, non adjustable dampners)
Spring rates 448/448
Stiffer then oem by F +43% R +31%
transfers 12% roll stiffness to the front
Special Note: A comfort ride system, spring rates make better sense then same G35 application, compare to Tein CS

HKS II (Monotube construction, adjustable dampners)
Spring rates 504/504
Spring rates F+61% R+47%
transfers 14% roll stiffness to the front
Special Note: sprung and valved to be HKS’s most aggressive product, it is a notch above the RS coil over on the track, compare to Tein Flex and Jic coilovers

HKS RS (Monotube construction, adjustable dampning)
Spring rates 448/448
Stiffer then oem by F+43% R+31%
Transfers 12% roll stiffness to the front
Special Note: “Marketed” as HKS’s track coil over with a good street ride.

Zeal function V6 coilover (Monotube construction, adjustable dampner) $2855
Full-length adjustment and height adjustment for separate setting of the height and spring preload
Spring rates 560/448
Stiffer then oem by F+78% R+31%
Transfers +47% roll stiffness to front

KW coilovers Variant's 1,2&3
Monotube construction,
V1=non adjustable dampning,
V2=adjustable damping,
V3=separate adjustability for compression damping AND rebound damping and is the only product of it’s kind at this time.
Spring rates Front 485lbs to 525Lbs Rear: 240Lbs to 548Lbs (progressive springs)

D2 Racing Coilovers (Monotube)
840/728 F+168% R+113% (wee bit stiff eh, the recommended rate to)
Transfers 55% roll stiffness to front
Side Note: Only known application of this coilover was by a vendor wishing to sell it, upon installation it was determined that the ride quality was so poor that they were pulled from the car and any idea of carrying the product was shelved.


Kg/mm DNA coilovers (Monotube construction, adjustable dampners)
See the Buddy Club specs on spring rates and stiffness to oem specs

T1R Type-E Suspension systems (Monotube construction)
Full-length adjustment and height adjustment for separate setting of the height and spring preload
Spring rates: 672 lbs/ 448 lbs
Stiffer then oem by F+114% R+31%
Transfers +83% roll stiffness to the front