Does anyone know the spring rates for the factory coupe springs?

My pics

 

They are the same rate as the 350Z spring and the sedan with the sport suspension.

314/342

What do you plan on doing with the rate info?

Here are the spring rates in comparision to all known lowering spring/coilover product made for the Z33/CPV35/V35. If a product is not listed, that maker refused to give out the info.

Eibach's as noted (first number is the softer initial rate, followed by the higher final rate)
350Z 296/384 front 316/421 rear
G35c 229/337 front 274/463 rear
G35s 259/334 front 359/413 rear

RSR 350Z springs (just a wee bit progressive F&R, maybe one coil is progressive)
345/417 F+10% R+22%
Transfers +12% roll stiffness to rear

RSR G35 coupe springs (progressive front and rear)
315/315 F+0 R-8%
Transfers +8% roll stiffness to front

Hotchkis 350Z springs (linear springs)
340/330 F+8% R-3%
Transfers +12% roll stiffness to front

Tein S-tech 350z (fronts are progressive, rears are linear)
386/402 F+23% R+16%
Transfers +7% roll stiffness to front

Tein H-tech 350z (fronts are progressive, rears are linear)
358/375 F+14% R+11%
Transfers +3% roll stiffness to front

Tein H-tech G35 coupe & sedan(fronts are progressive, rears are linear)
324/260 F+ 5% R-22%
Transfers +27% roll stiffness to front

Tein S-tech G35 coupe & sedan (fronts are progressive, rears are linear)
358/274 R+14% R-18%
Transfers +32% roll stiffness to front

Tanabe GF210 Series 350Z
336/375 F+7% R+10%
Transfers +3% roll stiffness to rear

Tanabe NF210 Series 350Z
314/353 F+0 R+3%
Transfers +3% roll stiffness to rear

Tanabe NF210 Springs G35 COUPE
297/336 F-5% R-2%
Transfers +3% roll stiffness to front

Tanabe DF210 Springs G35 COUPE
308/353 F-2% R+3%
Transfers +5% roll stiffness to front

Tanabe NF210 Springs G35 SEDAN
297/269 F-5% R-21%
Transfers 17% roll stiffness to front

Tanabe DF210 Springs G35 SEDAN
286/280 F-9% R-18%
Transfers +9 roll stiffness to rear

Kg/mm springs 350Z
DR21 super sport 15mm drop
246/398 front 252/409 rear

Kg/mm springs 350Z
DRacing 30mm drop
252/454 front 252/482 rear

Espelir coupe springs (the U.S. importer recently changed specs, I do not believe the newly listed specs are correct, since the new one's are extreamly high. And when I called the company to ask if the springs are linear or progressive, they told me Linear, turn's out they were absolutley wrong, they are in fact progressive. I show the old specs for those reasons, take it with a grain of salt, same thing for the 350Z fitment)
409/460F F+30% R+37%
Transfers +7% roll stiffness to rear

Espelir 350Z springs
381/460 F+22% R+37%
Transfers +15% roll stiffness to rear


Tein Flex
672/672 F+114% R+98
Transfers +16% roll stiffness to front

Tein Flex JDM specs (can be special ordered est 6-8 weeks delivery)
560/560 F+78% R+64%
Transfers 14% roll stiffness to front

Tein Basic
504/504 F+61% R+43%
Transfers +18% roll stiffness to front

Tein CS (Monotube)
392/392 F+25% R15%
Transfers +10% roll stiffness to front

Nismo S-tune (uses progressive springs, especially in rear)
350Z/G35 Coupe
448/504 F+43% R+48%
Transfers +5% roll stiffness to rear

Nismo S-tune (uses progressive springs)
G35 Sedan
347/342 F+10% R+0%
Transfers 10% roll stiffness to front

Buddy Club Racing Spec coilover (Monotube)
748/280*
(very likely run's rear springs on the dampner body and not at the oem rear spring location)

Jic Flta-2 350Z fitment (Monotube)
560/672 F+78% R+98%
Transfers +20% roll stiffness to rear

Jic Flta-2 G35 coupe (Monotube)
560/560 F+78% R+64% $1750
Transfers 14% roll stiffness to front

Jic Flta-2 G35 sedan (Monotube)
504/392 F+61% R+15%
Transfers +46% roll stiffness to front

Cusco Zero 1&2
560/392 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.)

HKS LS+ (rear springs are progressive)
496/440 +58%front +29%rear
transfers 29% roll stiffness to the front

HKS LS G35
448/336 43%front -1%
transfers 44% roll stiffness to the front

HKS LS 350z
448/448 43%front +31%
transfers 12% roll stiffness to the front

HKS II 504/504 +61%front +47%rear $1600
transfers 14% roll stiffness to the front

KW coilovers Variant's 1,2&3
Variant 3's are noteworthy as the only known coilover for these cars where the dampners are adjustable for compression and rebound independently. They also differ in using progressive springs front and rear
Front: 485lbs to 525Lbs Rear: 240Lbs to 548Lbs

D2 Racing Coilovers (Monotube)
840/728 F+168% R+113% (wee bit stiff eh, the recommended rate to)
Transfers 55% roll stiffness to front





"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke

G35 6mt

 

This post should be in the FAQ section. Great info.

Gsedan, would it be correct to guess that the JDM Flex with EDFC could have a min stiff +50% and max +100% over stock given the 78% avg?

 

xswl0931, that might be the picture that the few owners of the original flex system would paint. I say "original" because when the flex was first marketed here it had 560/560 rates. It was changed in the US a while back. Getting the JDM flex would take a while, 6 to 8 weeks to arrive from Japan by ship. Price is the same since your ordering dealers cost is the same as the USDM flex.

"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke

G35 6mt

 

Gsedan35

Thanks!

 

Remember to convert the spring rate to Actual wheel rate [how much the mounting angle and mounting position away from the wheel hub reduces the springs force]

Normal wheel rate ratios might be 150 pound/inch front and 120-130 pound/inch rear

 

<blockquote><font class="small">In reply to:</font><hr>

Poster: Q45tech


Remember to convert the spring rate to Actual wheel rate [how much the mounting angle and mounting position away from the wheel hub reduces the springs force

Normal wheel rate ratios might be 150 pound/inch front and 120-130 pound/inch rear

<hr></blockquote>


Getting into wheel rates is rather over the top here and will confuse people without cause, it's simply not something they need to get into to make mild improvements. Replies should be shaped to the members requirements and goals. As such that means extra work to vary the content as to best help them. It takes that willingness to manage the flow of information in a responsible fashion to truely help the greatest audiance on any forum and lets them know they are free to ask for additional info at any time.

As a baseline spring rate date gives members the ability to make simple judgement calls and to see that some spring choices can have consequences. If they want serious improvements to the car, then the discussion's can begin to touch the wheel rate topic. But realistically wheel rate is only a fractional tid bit to a much much bigger picture. I would certainly hope that any one planning to spend big money on suspension mods would already have discovered or heard about such things.

I have had the following on hand for some time, simply posting for the curious.

Spring rate to wheel rate convertion chart, it reads as follows
spring rate lbs to wheel rate lbs.

Numbers are a simple matter of multipling front spring rate by front motion rate of .79 Same for the rear where the motion rate .36 (due to the inboard location of the rear springs and the length of the lower arm offering up less leverage to the wheels) So anyone can do the math for any product I don't list.

Oem springs.
Front:314 to 249 Rear:342 to 123

Espelir coupe springs
Front:409 to 323 Rear:460 to 166 F+30% R+37%
Transfers +7% to rear

Espelir Z33 springs
Front:381 to 301 Rear:460 to 166 F+22% R+37%
Transfers +15% to rear

Tein S-tech 350z
Front:386 to 305 Rear:402 to 145 F+23% R+16%
Transfers +7% to front

Tein H-tech 350z
Front:358 to 283 Rear:375 to 135 F+14% R+11%
Transfers +3% to front

Tein H-tech G35 coupe & sedan
Front:324 to 256 Rear:260 to 94 F+ 5% R-22%
Transfers +27% to front

Tein S-tech G35 coupe & sedan
Front:358 to 283 Rear:274 to 99 R+14% R-18%
Transfers +32% to front

Tein Flex
Front:672 to 531 Rear:672 to 242 F+114% R+98
Transfers +16% to front

Nismo S-tune
Front:448 to 354 Rear:504 to 181 F+43% R+48%
Transfers +5% to rear

Jic Flta-2 *350Z fitment
Front:560 to 442 Rear:672 to 242 F+78% R+98%
Transfers +20% to rear

Cusco Zero 1&2
Front:560 to 442 Rear:392 to 141 F+78% R+15%
Transfers +63% 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.)

Tein Basic (HKS Hypermax II use's same spring rates)
Front:504 to 398 Rear:504 to 181 F+61% R+43%
Transfers +18% to front



"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke

G35 6mt

 

cajo, your welcome, I'll add to the list from time to time as additional products with rate info comes my way.

"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke

G35 6mt

 

<blockquote><font class="small">In reply to:</font><hr>

Tein Basic (HKS Hypermax II use's same spring rates)
Front:504 to 398 Rear:504 to 181 F+61% R+43%
Transfers +18% to front

<hr></blockquote>
Can someone please explain what "Transfers +18% to front" means? Does this have to do with under/over steer?

Never mind. A search on 6MT.net gave me the answer I was looking for (after searching FA and G35driver)...

<P ID="edit"><FONT class="small"><EM>Edited by neffster on 10/06/04 04:05 AM.</EM></FONT></P>

 

Please explain where how you derived [measured] the front spring motion ratio as 0.79? Agree with rear but front seems off?

 

http://www.proshocks.com/calcs/imotion.htm

A calculator to derive wheel rate from spring rate

 

You wouldn't happen to know what the part numbers are for the different Nismo sedan and coupe/350Z springs? If not, where is a good place to check?

Each Nismo spring has a part number on the spring, as I'm sure you know.

Thanks in advance

 

Ideally you want the front to rear roll stiffness [sum of springs and sway bars]equal to the weight ratio on the front to rear wheels. Unfortunately this varies with body position and interior weight load [passengers and trunk] and after market wheels and tires and amount of gasoline in tank..............so this ratio is a moving number.

Statically the weight ratio might be 54/46 empty fuel and change 8%/[54/46] or ~~4% with a full tank..........when you get too close to the edge 4% is a big number

Springs usually sit in rubber seats and sway bars have rubber bushings so the numbers start out soft till the bushings - seats get fully compressed [nonlinear in the first few inches of movements from static. Shock absorbers have stickson based on velocity and internal temperature of fluid and internal gas pressure changes with temperature.

Anyway the factory designs in understeer [the front suspension is stiffer than the ideal weight ratio would dictate]. Also additional front stiffness is added to correct for the situation when rear tire friction drops [cold temperatures] and any form of acceleration where the friction must be shared.

What is spot on in warm weather on a dry high adhesion road surface will be dangerous in cold rain where any acceleration can break the rear end free thus deliver over steer.

Important to think about cold wet when setting ratios or at least have a summer vs. winter setting.

Big BMW have an active rear sway bar stiffness which is tied to windshield wipers [rain detection]. Race cars have variable rear bar [cockpit adjustable] to compensate for fuel weight drop and tire vulcanization [in 100miles][from cornering heat].

Measuring springs alone is great but you must consider and check HOW they act when mounted on the car. Same with sway bars. You must know the motion ratios [and corner weights] and expected G loads [to calculate added weight transfer] when deriving the roll couple ratios.

Consider that a drivers weight sitting offset from center line yields significant variations in left to right G [cornering] capability.......racers trim the springs [rates lengths] to compensate for even a 10 pound side to side variation.

It isn't all that complicated, you just must be sure of exactly what you want to achieve.