can it been done? I found some threads talking about the spring rates, but never said if it could be done. and I've searched alot. I'm not really too familar with spring rates. thanks for any positive input. thanks I'm looking to lower more but no need for coilovers.

chris

 

come on guys 160 views and no hits.lol

 

Don't see why not. The spring seats on the front coil over appear to be OEM design, so any 350Z compatible spring should work. The probability that a member bought S-Tune suspension, then tossed the springs in the trash is slim to none.

 

thanks David for the reply I actually bought the Z with the Nismo s tune suspension but was just wanting to swap out the springs to lower the car a bit more.

 

Nismo S-tune shock and spring setup 350Z (twin tube, fixed height)
.6"/.6" drop
Spring rates 393*-448/254*-504
*estimated initial spring rates

Eibach 350Z sportline progressive springs 1.2"/1.2"
Spring rates Front: 239/400 Rear: 257/435 (initial/final)

Should be fine, your within 54lbs in the front and 69lbs in the rear. I don't have shock dynos to draw on, so I'm going on the idea that being slightly softer is a lesser evil then going slightly stiffer in rate.


You do have another 1.2" drop spring on the market that is even closer in rate, not sure who even carries them in that states however.

Kg/mm DRacing progressive springs 1.2”/1.2”
Spring rates in LBS initial/final front 252/454 initial/final rear 252/482 rear

 

Have the sport lines and S tune shocks quite a nice combo.

 

turns out I have the Nismo 350z Oem struts, could sportlines work for these? otherwise I'll just sell my nismos and buy oem struts or koni's

 

That should work..but you're going to go much lower and will require camber adjustments.

I have Nismo S tune (NOT OEM NISMO)...lowered about 1" front and 1/2" rear.
I'm going to install Eibach PRO Kit springs on the rears. This should lower the car another 1/2" in the rear. Fronts won't be touched. The rates on these are Progressive 316/421 vs 254/504 for the S tune. I actually think I'll be better off with a narrower range in the rear and slighly softer rate (like stock 04.5 rating). I find the higher rate on S tune tends to kick out the rears more on application of throttle exiting a turn.
I'm looking for less tendency there with this change...allowing me to be more aggressive on getting back on the throttle sooner in mid turn.
Stay tuned.

 

Excuse me if I'm way off base here, but wouldn't you want to reduce squat to acheive more traction? Seems like if you go to a softer spring you're just letting the *** end become more sloppy and that seems like a backward move. I really don't know, I'm just speculating. I've got alot to learn.

 

You're talking extremes here..the springs I'm going to are still fairly stiff. Hell, look at many other aftermarket ratings (Hotchkiss) and you'll see SOFTER THAN STOCK ( which is 421)!

In fact, the INITIAL rates are STIFFER than the S tune's. I don't think a WIDE range on the S tunes progressives is good either. As far as squat...these will not squat more due to initial stiffer setting. What I was talking about was increased throttle OVERSTEER with the stiffer S tunes...and that comes on more suddenly (read not as predictable) as well.

 

Stiffer the spring the less traction you have, when the car squats , weight transfers adding traction.

 

Makes sense. I was thinking backward based on something I heard a while back.

I just re-read Ron's post in question and it made much more sense this time.

 

I found a post that validates my claim on softer rear (vs S tune rear set up 505 lbs):

https://my350z.com/forum/9255513-post5.html

For someone that know's the car is a daily driver, consider 560/448 as your practical limit.

As far as front to rear rate balance, it's ok lower or even. As rear rates get beyond 500lbs in rate, you'll find the car more willing to rotate on less then smooth daily driver road surfaces. Lower rear rate setups exist to extract more rear grip do to the car's weak oem limited slip and because the car has built in anti dive and anti squat elements whereby the lower rear rate helps keep the rear more planted (like being able to roll into the throttle sooner when comming out of the hole or corner).


and here..same poster (G35Sedan)

http://www.vqfrenzy.com/threads/543-...ll=1#post54957

Currently back on the Koni setup 448/427
From experience, do not write off rear rates that are at least 342lbs. While the higher rear rates make the car feel more alive, you do have greater sensitivity to the throttle and less traction coming out of the hole. Yes, the lower rate can slightly increase understeer slightly, but you get greater forgiveness from the throttle and more traction from the rear that allow's you to roll on the throttle sooner as cornering loads ease. My testing agree's with Unitech/truechoice, that high spring rates overall are not needed to get good performance, nor is a high rear rate the automatic answer. Though I didn't start out thinking that way, actual testing showed me otherwise

Odd..set up in red will almost be EXACT same spring rates I will have with Nismo front (448) and Prokit rear (421)..albeit a progressive rear......and, in my case, Nismo S tune shocks.

 

Just swapped out the rear Nismo S Tune springs (505lbs) for Eibach Prokits (421 lbs). It lowered the rear another 1/2"..perfect. Rear end not as bouncy and isn't *tail happy* under acceleration in turns. Much smoother on rough pavement too. Glad I did this.

Foot note:
Car still has S Tune shocks and S tune front springs.

 

This set up is really amazing.
Car likes stiffer front and basically *stock* (revised) rear spring rates. I have Nismo S tune (448lbs) up front with Top Speed (Cusco) SB and 245/40/18 on 9.5s. Rear has Tanabe SB with Nimo S tune shocks and Eibach Pro Kit springs (421lbs) with 275/40/18 on 11's. Took car out today on mountain roads and could, for the first time, hammer it exiting the turns. I can now toss this car at will. High speed sweepers (110mph) are absolutely rock solid. Best of all ride is like butter...unless I hit expansion joints on some strips of fwy.
I finally got the set up I've been looking for. Maybe I should take 'er out to Willow Springs Big track...stay tuned.

 

Speedventures early June, lets play!!

 

Have you run the big track?

 

A couple times, my best is a 1:35.1 so far

 

Great time...that's about what I was turning in my 944T..before they widened turn 1. That change cut times down by 2 sec, but I never ran that configuration. That was back in 1990. I had special track tires and race pads though.
I saw the schedule...I might do the Thursday, when few cars are out. If I go, I'll run stock tires and Stop tech pads. I don't have a helmet...I think they rent em out?

 

I know they rent them, Thursday i doubt i can make it. Sat if anything, also looking at Buttonwillow with Extremespeed for the Z/G Challenge