Several posters have stressed that the Eibach's are non-linear pogressive type of springs. Are they saying that this may cause a problem with unpredictable handling on the street and track? I'm interested in them only because I need springs to go with the Koni's I'm ordering. I'd like to eliminate the bounce/porpoising/harshness, but I don't want to enter into a situation with unpredictable handling.

 

TheLex:
Get the Hotchkis 350Z Springs and save your self the worry.

www.hotchkistuning.com

Or buy my Eibachs Pro Springs and wonder. See sig

I guess I need to work on my Used parts sales strategy.

Ha !

Cheers Amy -

 

thanks Amy, I was thinking of getting the Hotchkis Sway Bar and Spring kit, since they're probably system matched. I'm a little leery of mixing springs, shocks, and sways from different companies since they really aren't engineered to work together. They just might have good synergy, or then again, they might not.

 

Progressive springs arent "unpredictable" but your turn in will be a little softer than you are used to. The progs will also offer a smoother ride when you are just cruising around. They do compromise a little performance for comfort. I want a set of linear springs myself, and will not be buying the Eibachs.

 

I saved comment's I've made on the topic before in a text file, here's a cut and past of them.

Their is more to progressive springs regarding the compromise on performance for ride quality. Progressive rate springs are a bad idea for aggressive driving for several reasons. Soft initial compression of the springs allows the car to roll more on turn in, then the momentum built up by this roll hits the firmer part of the spring. This puts a heavier load on the outside than linear springs because the linear springs would not have allowed as much roll in the first place. And most progressive springs don't have "seamless" transitions in rate. They change rate in significant steps as active coils bottom on each other. A sudden change in spring rate, while at the traction limit, can result in a nasty slide. And further still, a progressive spring has two or more rates on one spring, right, that's what makes them progressive. ...let's assume that for the first 2 inches or three coils, the rates are 250lbs per inch and that for the next three inches, the rate is 350 lbs per inch. Therefore, when at rest, suspension will be compressed on the 250lbs spring section, and the next inch of movement will be in the 350 lb per inch range.

Now let's use the same scenario......a corner is entered and the outside spring is compressed one inch and the inside spring is extended .75 inch...rememeber the rates!

Now you encounter a bump in the corner...and since you are currently using the outside spring at a rate of 350 lbs per inch and the inside spring rate of 250 lb per inch... and the suspension is compressed the additional two inches....what happens to the spring rates? Since they differ, the chassis rotates around the roll axis... and the vehicle attitude changes/rotates differently than when in steady state cornering! Its motion becomes slightly skewed since to offset the bump deflection each spring must work through a different spring rate! If you were to then hit another bump, the attitude would change again...and so forth. All of these things of course would not happen with linear springs.

Progressive springs can be made to work in very limited conditions where the parameteres are well known, like a specific road course where telemetry is constantly giving feedback to help select the right rates.

 

thanks for the replies! Gsedan35, your info is exactly what I'm worried about. I don't want to end up with unpredictable snap oversteer. Controllable oversteer is a good thing. The unpredictable kind is NOT.

I'm hoping the combo of Konis with the Hotchkis springs/sways will eliminate the harshness/bouncing/purpoising. It's been posted here that the stock setup feels like the struts are coming up through the A pillars or dashboard, and that's exactly how it feels it me.

And alternative are the luxury master springs but I figure at least the Hotchkis are matched.

 

the bottom line is this - for most people, the Eibach is just fine, as they don't drive the car anywhere near its limits. The progressive spring, by nature, will be far more forgiving in terms of comfort for street driving. I have used Eibach's in cars for nearly 10 years now, and have never had a car simply snap oversteer because them.....that tends to happen more with the wrong line in a turn which we have all done!

For those pushing the car harder, a linear spring is a better choice, at the expense of some ride quality (depending on the spring rate)

For those frequenting the track, or wanting the increased adjustability and the ability to select your own spring rates, there are plenty of coilovers to satisfy this requirement

 

ok so what would be a good choice for someone just wanting to add lowering springs that does drive aggresive?

 

progressive springs are best for spirited daily drivers with large rims...

the progressive springs will absorb more small shock rather then the tires so you will get more tire life with a progressive spring then with linier... but you ascrifice corner handling..

Eibach Pro Kits instock $205 plus shipping

http://www.performancenissanparts.co...roducts_id=304

 

You may also look at Tein S-Tech. They are Linear in the front and Progressive in the Back...

 

ok cool! hey jason any more of those stop tech brake kits on special you had with the rotors,pads and brake lines?

 

What is the difference in ride between Eibach and Tein?

 

Are the RS*R linear?

 

Diesel350> Eibach has twice the drop, progressive all around. Tein is just progressive on the front, linear in the back. Also differing rates.

VR3> RS*R claims them to be -- but seeing them first hand, they definitely looked tighter at the edges on two of the four (either front or back).

Anyone have a pic of these?

 

I've asked RS*R and they said that they are liner in the back and progresive in the front.

 

yup

 

Sorry about the Delay in responding..

I have my friend EH doing some testing with a G35C owner..

The results were obvious with the heavier car.

The Eibachs were mis matched.. But the Hotchkis and 350Z rear shocks made the car nice and stiff in the corners -

The guy said - I have one less steering change to make in the turn.

I think this is the Rear Wheel equvilent of Not having "BumpSteer" in a front wheel drive..

This car does not have Koni's - it is a car that needs the Rear 350Z shocks.. So at the moment we are giving the Pilot 350Z parts in exchange fro G35C parts...

Cheers Amy -

 

G35C Eibachs use totally different spring rates then 350Z Eibachs. Of course Eibach is working around the fact that G35C shocks are valved a lot softer then oem Z shocks. Oem to oem, the Z and G35C run the same oem springs and sway bars, oem shock valving favor's the Z. I've seen a G35C equipped with Eibach's simply drive off, the suspension sea sawed up and down with weight transfer issue's a frightfull amount.

350Z 296/384 front 316/421 rear
G35C 229/337 front 274/463 rear

 

So what springs would you guys recomend? I would like a better ride as well as lowering the vehicle a bit. I'll be running 18" rims.

 

The Eibachs work great for street use. I've been running them with the stock shocks for a year now. At track events there is roll in the turns but it's not excessive and I have no trouble hanging with 'vettes and 911's (non-turbo) all day long.
If you don't have money to burn the Eibachs are a nice compromise.