I have an 06 5AT coupe with Zeal XSs true coilovers, with 12kg front and 10kg rear. The standard spring rate for them is 10kgF and 8kgR so mine are just a little stiffer.

My problem is I'm getting alot of oversteer since I put them on. I now have my front sway bar set all the way stiff and my rear all the way soft, I also have the front dampner set all the way stiff and the rear at the softest setting. I'm also running the front tire's a 5psi less then the rear. While all of this has helped I think the spring rates are off.

I have read that when you go to a true coilover vs the OEM location that that effects the spring rates. I trusted Zeal to have the right R&D for our cars and ordered the coilovers but I see the the Stance true coilovers come with a 12/5 setup.

I Auto-X my car and am a little fustrated trying to get the car to handle nutural.

I'm thinking about changing my spring rates to a 14/8 or going back to the OEM location with the SPL Midlinks.

I would like to hear from Gsedan35 or wa2good as both of you have some good expertise on the G's supension or anyone else that may have Zeal's and run into this.

 

I came really close by buying a Zeal true coilover setup that Performance Nissan had at a crazy price last year. The plan was to convert them to a oem rear spring location. And I gotten myself past not finding any info from endless or anywhere else about what made them tick (at least Ohlins publishes things you can read to begin to understand why they cost what they do). What made me bail and run away was doing the math on just how much spring rate made it to rear wheels. Knowing that, It's totally understanding to me why your having your issues. With the amount of rate testing that I have done and tried out, I just don't understand the logic of that much rear wheel rate. Course I'll be the first to admit, drifting specs just aren't my thing to learn or have a total grasp on.

Let's look at the numbers.

We need to pay attention to the "Wheel rate", it equals the amount of spring rate that makes it to the wheel to perform work.

Your oem specs are

if you don't have the sport suspension
Spring rates314/342 (wheel rates are 149/144

if you do have the sport suspension.
Spring rates 314/427 (wheel rates are 149/180)

Please keep in mind that I adjusted the XS specs below to reflect how our's have stiffer spring rates then normal

Zeal XS with springs in oem locatoin
672/560 (wheel rates are 318/236

Zeal XS with springs on rear dampner (true coilover)
672/560 (wheel rates are 318/560
672/448 (wheel rates are 318/448

Stance with springs on rear dampner (true coilovers)
672/280 (wheel rates are 318/280

Stance with springs in oem location
672/616 (wheel rates are 318/259)

Does this mean you should run out and buy the Stance setup, heck no!.

IMO, pull the rear dampers and send them to Endless. Get them revalved to run with 5Kg rear springs on the damper. You can buy 8" tall 2.5 ID 5Kg springs and run them again on the rear damper's. You could also buy the SPL midlink product to run in the oem location. Let me give you a plan C. Buy either Eibach ESS or Hypercoil 9.5" tall 5" OD springs that are 625lbs in rate and buy Tom Motorsports coilover setup you see on Ebay for $100 shipped. Your only after one thing in the kit, the adjustable rear spring seats. Total cost $250, a lot cheaper then the SPL setup. I have the adjustable rear seats from Tom Motorsports, no complaints about the quality of the parts.

 

Gsedan35, thanks for your response and the plan C. I will look into that and the cost to have Endless change the spring and revalve.

What is the formula that you use to convert the spring rate to the rate at the wheel??

 

Your welcome. I do want to say, I have zero against the SPL mid link, just wanted to offer you a sensicle option that would control costs.

Here's the math to get the wheel rates, it is for a oem rear spring loction. A true coilover setup in thre rear attaches directly to the wheel hub, meaning it transfer's 100% of the springs power to the wheel.

Math example
672 X .688 X .688 = 318
560 X .649 X .649 = 236

Math is courtesy of member "hippie" from my350Z.com

 

Ok, just thought I would update my on thread. Since you can change spring rates by +or- 2kg without having to revalve I lowered the rear to an 8kg and raised the front to a 14kg. This has solved the problems I was having and now the car handles pretty nutural. Now I am very happy with the way it rides on the street and at the track.