Apexi350z

iTrader: (3)

I currenly have Eibach Pro-Kit on my car, but I think they are too low when driving around bumps and potholes in the Houston area...

So I am thinking about changing them out for either Tein S.Tech or High Tech springs.

After research the site, I found out that:

Stock = 347 Lbs/in (front) | 419 Lbs/in (rear)
S.Tech= 386 Lbs/in (front) | 402 Lbs/in (rear)
H.Tech= 358 Lbs/in (front) | 375 Lbs/in (rear)
Eibach= 384 Lbs/in (front) | 421 Lbs/in (rear)

What I am interested is the H.Tech, which has similar spring rate in the front compare with stock, but less spring rate in the rear..
What does it really mean in real life?

What happens when it's less spring rate in the rear? will it cause oversteer/understeer? ride quality will improve or otherwise?

I like the Eibach's ride so far, which eliminates most of the bounce, but it's just too low.. I would probably go with a 0.5" drop or so....

Any advice are apprecieated!

jmark

iTrader: (1)

Eibach's are progressive springs not linear like the stock.

benzz280

iTrader: (2)

how bout the TEIN springs?? linear or progressive?

Apexi350z

iTrader: (3)

Both S.Tech and High.Tech are Progressive Springs..

benzz280

iTrader: (2)

then they should be ideal for you, the H tech lowers the least!
by the way less spring rate means less stiffer
if you like to oversteer, then go stiffer in the rear then the front
stiffer springs generally mean harsher ride

let me know the ride quality if you ever get the H tech, i have been contemplating to get this or the expensive Konis shocks to reduce the bounce

Bud

I installed the Tein S-Tech springs on my Z the springs lowered the car approx. 3/8". The ride was slightly improved. Only when I changed the shocks did the ride get where I wanted it.

Apexi350z

iTrader: (3)

thanks for the info!

350Zteve

iTrader: (6)

In general terms, the end of the car you add stiffness to, you decrease traction too. Therefore if you stiffen the front, you get more understeer. Softening the rear again provides understeer. I would avoid any spring kit that softens the back and stiffens the front, that will just increase the understeer.

Most every car comes out of the factory set to be understeer biased. The Z is no exception. If you want to get the car to be more neutral. Increase the rear stiffness via springs or sway bars.

Z-Noob

So for the person looking for a very little lowering without f'n up the car, which springs are the ones to go with. I don't care to spend too money on coilovers, just springs. thanks

350Zteve

iTrader: (6)

The RSR's have stock spring rates and lower the car 15mm. These would be a good choice.

Z-Noob

I noticed you have the eibachs. How do you like those? I was considering those just based on my previous experiences with Eibachs on other cars.

Zster

I just got the Tein S.tech installed... it didnt lowered my car significantly... The ride quality improved alot over stock... i should have gotten the Eibach prokit.... because i like my wheel closer to the fenders.... anyone with Eibach prokit and wanting to trade???

JasZ

Does anyone know what the spring rates are on the '04 Roadster? I love the ride as it is stock, but I'm pretty sure I'll want to lower it after getting my new wheels.

I live in Houston too. Man, the roads are a nightmare everywhere you go.

Speedracer

Properly eliminating the "bounce" and maintaining ride/handling qualities will require a shock and spring upgrade. My suggestion is that if the Eibach springs are too low, keep the stock springs and change the shocks to an adjustable unit such as Koni Sport. Reducing the rear spring rate alone will increase the understeer...definitely undesireable. Alternatively you could decrease the rear spring rate and add a larger rear anti-sway bar, although most people seem to feel that even the stock set-up needs a larger anti-sway bar. Quite honestly, if money is an issue, it's hard to "fix" this suspension. If you track your car regularly there is no substitute for coilovers with a higher rear spring rate, otherwise, stock suspension with upgraded sways work very well.

Gsedan35

iTrader: (10)

I'm the source for the oem spring rate info,.........BUT!!!
I have revised the oem rate info, I did a post announcing the revision, the old rate data is incorrect.

Please take note of the corrected oem rate data which is,....
314/342 (Hotchkis say's oem is 310/350, which is within the nominal margin of error for coil spring rate testors).
I have not gotten my hand on oem 04 Z springs from the revised suspension setup, they are said to possibly be slightly stiffer then 03 springs. It only takes a fractional increase (or decrease) in wire diameter to effect a springs rate.

zxsaint

Could you explain this in more detail? In what way do you feel theres an improvement, considering the springs are stiffer?

DM4

I have conflicting info on spring rates for the 04 Roadster. Some sources say it is the same as the coupe , others say it is different. No one, including dealers and aftermarket manufacturers, have been able to give me a definitive answer. I did speak to Paul at Nimso and he stated that the Nimso spring/shock kit is applicable to both the roadster and coupe even though the web site indicates it is only usable on the coupe.

mickyboy

Spring are different in coupe & roadster. We have just gone thru this in Oz & they Nissan have different part numbers for the coupe & roadster springs!