Why does the 350Z spring rates have to be so high compared to cars like the RX-8 and S2000 to get good handeling? Those other cars have something (besides weight) better than us?

Just wondering =p

 

The Z uses 314*/342*, what does the RX8 and S2000 use?

*car's built after 11/30/03 are supposed to use a slightly higher spring rate as part of revised suspension settings, until I get my hands on a set, I can't give a amount on post 11/30/03 cars till then.

 

RX-8s are

Stock RX8 6spd
F 155.61 lb/in
R 112.86 lb/in

thats like ALOT lower than the 350Z (no wonder it has a nicer ride?)

 

I'm confused! On several posts on this sight stock spring rates have been stated at F347-R419. I'm considering Tein H tech to "soften" my ride and they are rated atF358 R375,what am I suppose to make of all the conflicting info?

 

I believe the H-tech's ratings are at full compression. The springs are progressive, while the OEM's are linear. The H-Tech's are softer at low to mid compression.

 

Let me undue your confusion. I am the source of the 347/419 oem rate info. I discovered a few months ago that I was in error and I did a post to correct myself. Problem is, not everyone say the correction post as the previous data keeps popping up. Of note is the fact that Hotchkis tested the oem springs and say's they are 310/350. We are close enough to each other to confirm each other. The difference between us can be explained by normal coil spring rate testor +or- error.

So, I am sorry for the confusion, I hope I've cleared it up for you. Corrected oem rates are 314/342.

 

Your on the right track. Tein H-tech's and S-tech's are progressive in the front and linear in the rear. The rates given by Tein do not reflect the softer progressive initial rates, but the firmer final rates.

Eibach and Kg/mm are the only two Z33 spring makers that admit what their initial spring rates are in addition to their final rates.

 

Well, keep in mind that the Z use's shock's that are dialed in to deliver a lot more stiffness then what you'd normally see on a car. Those shock's are a blessing and a curse. On one hand you would not have as much universal automotive press praise for the car's handling. And on the other you would not hear so many complaints about bounce or harshness. Equip the Z with softer G35 coupe shocks and all the ride quality complaints vanish, but, all the performance benefits are reduced in like kind.

On the oem RX8 and S2000 spring rates vs the Z. One thing we have to know is the motion rates of both cars. In other words, how much of the springs force actually is leveraged to the wheel of either car(wheel rate). For example on the 350Z (G35 too) the front motion rate is .79 and the rear is .36 That means that for every 100lbs of spring rate 79lbs is exerted at the front wheels and in the rear 36lbs is exerted on the rear wheels for every 100lbs of spring rate. The S2000 and RX8 may have very high motion rates where the cars place their springs closer to the wheels to leverage more spring stiffness to the wheel.

Let's apply the Z's moton rates to get the wheel rates. First number is the spring rate followed by the actual rate leveraged at the wheel (wheel rate)


Front:314=248 Rear:342=123

What "if" the RX8 had motion rates of .90 and .65

Front 156=140 Rear 113=73

The Z is still higher of course.

Then, how does the after market dial in the spring rates for the RX8 and S2000? Here's Tein's take on that.

Tein flex RX8 504/391

Tein flex 350Z 671/671
(original flex system used 556/556 rates as do the JDM ones now)

Tein flex S2000 559/671

S-tech S2000 296/363

S-tech RX8 207/145

S-tech 350Z 386/402

I'm not a expert, but the above are somethings that crossed my mind on the subject.

 

KO: I have corrected my numbers on oem spring rates. Now let me state the following,and if you would give me your opinion.04 Z Touring 18'g35 wheels and tires,And I want to soften up the ride. I am presently running g35c sport shocks on the rear and there is no significant improvement.I have a set of g35s sport shocks and I intend to try out the rears next. I also understand the g35c standard suspension shocks have worked for some people.So#1 stock springs with some combination of g35 shocks,coupe or sedan, sport or standard.#2 Tein H tech with stock shocks or again some combo of g35 shocks.As you say you may not an expert but I for one would value your opinion. Thanks