I have searched almost every 350z parts place I can think of and I have also searched on yahoo. Does anyone know where I can find these? I could probably buy them from KW, but I didnt know if someone else had a better price.

 

Just want to make sure you know two things about them. They use progressive springs, front rate spread isn't soo bad, but the rears do have a sigficant spread. And that taking advantage of their ability to adjust compression and rebound is not a task to take on for the faint of heart of the unprepaired. I believe that the member name who was behind the original ground buy for them is MSV, you might want to search his posts for KW.

 

I knew that they were progressive rate, I had heard that that is not really a bad thing. I am not planning on adjusting the compression until I find someone that knows what they are doing, but I do plan on adjusting the rebound. I am trying to decide between this setup, Tein Flex, HKS Hypermax II, or HKS Hypermax RS.

 

Progressive springs are scarce to none existent in motorsports for valid reason's. They are a compromise between performance, at the limit behavior for the sake of ride comfort. The KW's have a huge differance in the rear rates between initial and final rates.

Spring rates Front 485lbs to 525Lbs Rear: 240Lbs to 548Lbs (progressive springs)

Easy to fix, simply install a pair of Eibach ESS springs 11" or 9.5" long or so and 550lbs in rate in place of the springs KW supplies.

As I've said in the past on the subject. 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 3 inches or three coils, the rates are 250lbs per inch and that for the next two 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.

 

I thought Eibach what progressive aswell? I was looking into KW b/c I don't want an extremly harsh ride on the street, but I want the option to track to track the car on occasion.

 

Try PM board memebr "lateapex"
He has a set of KW V3 Coilover for sale earlier.

 

After researching I think I like the HKS Hypermax II better.

 

long wait for hypermax2 since they are not made for US market anymore

 

When did this come about?

 

seems like HKS US discounnect hypermax2, since this modle is no longer on HKS USA's website.though you still can get it from Japan HKS.

 

For these car's the Eibach prokit lowering springs certainly are progressive. But, their ESS spring is a 5" outside diameter spring, same as the oem rear springs. It's 100% linear. You can get it in different length's and spring rates to suit your needs (125lbs-700lbs).

http://eibach.com/cgi-bin/htmlos.exe...04892100014340

1. North America
2. ESS-Main
3. Imperial
4. pick your length
5. 5.00

 

That never dawned on me, very interesting. Not that I agree with such a move by HKS.