Slow*Jim

iTrader: (5)

I am looking to do a budget track setup using Koni yellows - but most of the off-the shelf springs I see for sale have relatively low progressive rates, some even lower than stock.

Who makes some track-friendly springs for our Z's that would give me performance comparable to mid-level coilovers?

I know I could also consider some custom-rate linear springs from TomMotorsport, but what length/rate would be optimal?

Thanks for the help!

nkohler

iTrader: (16)

I believe nissan sells T2 springs that are quite stiff.

http://www.mynismo.com/products/?id=2792

huyrua

iTrader: (30)

Swift Springs = linear, less weight, will not bind, no sagging

I have the sport compact and it's stiff. Forgot what the spring rate is. If you want stiffer get the spec-r.

Gsedan35

iTrader: (10)

The Nismo T2 springs cannot be run productively with OTS Koni yellows without a revalve, even then your going to push the core shock design beyond what it should be asked to run since hysteresis levels (internal pressure imbalances or phase lag) are already on the high side as is, asking the shock to do more is asking for this to get worse, TcKline DA's are a perfect example of this.

.

nkohler

iTrader: (16)

Thanks for the info however it would probably be beneficial to all that you suggest a dampener that WILL compliment the T2 springs in case they do want to run the spring rates that the T2 springs provide. Suggestions?

Gsedan35

iTrader: (10)

The TomMotorsport springs are no longer imported with the 500/500 spring rates to my knowledge, IIRC the front springs are much softer now. Though I have the rear part of the kit and I can confirm the rear springs are 500lbs.

What rates do you want to find?

Do you already own OTS Koni yellows?



I have Koni's that I pulled from the car awhile ago, before I did I tested them with Tein tapered linear springs on the front. I was able to use them by making my own 6061 aluminum lower spring seats. The Tein springs are 448lbs and drop about .5". Nice thing about the Tein tapered springs besides being linear, they reuse the oem upper mount, though using Koni top hat's and modifiying the oem upper mount isn't the end of the world. For the rear I just ran oem 427lbs springs on cut down oem upper seats. I've also ran the front Koni's with 560lbs springs, which IMO wasn't productive.

Slow*Jim

iTrader: (5)

Not yet, I just figured that would be the most cost-effective way to enhance cornering performance at the track while maintaining decent streetability. I think the T2 springs are a little more harsh than what I'm looking for.

These look like a pretty good rate for the track, and not too punishing on the street.

Swift Spec-R:
Spring Rate - initial/final
Front: 291-392 lbs/inch (5.2kg - 7.5kg)
Rear: 280-448 lbs/inch (5.0kg - 8.2kg)
Drop Front/Rear
1.2 inch/1.0 inch

z-u-later

iTrader: (43)

I have the Tom Motorsport adjustable springs coupled with the Koni Yellows. This is a real stiff setup for the street but perfect for the track. And the price was right.

Gsedan35

iTrader: (10)

IIRC you've had yours for awhile now. They changed the makeup of the front springs so they are softer then what your running. I understand the thinking about being perfect for the price, but having driven on the same shocks on simular spring rates, your not getting perfect shock control and it is costing you grip and time. And I also get it that installing something better tend's to be gawd awfull expensive, so that's where my understanding of "perfect for the price" comes from. And to give you a second opinion on the subject, here's a comment from a fellow Z owner that drove a Z with the same shock and spring setup.

"Just want to let you to know that I had a chance to ride in a Z with koni yellows and #500 springs at the track recently. The valving of the yellows is not as good as what I'm running. I had tons more stablility in the high speed stuff. The higher compression is a must-have at the track."


What would I run instead, revalved Bilstein HD's or Anze Engineering single adjustable Penske 8300's.

Carbon-Z

X2. It's either Z-U's driving or his suspension but he does not do well compared to other cars on the autox and road courses. I have seen him lose it many times due to his overly stiff suspension.

Remember, overly stiff suspension does not mean you handle well. Your car still needs to absorb the bumps some to keep it stable and handle well.

Edit: This is not a attack towards Z-U, this is advice. So don't take it that way which you usually like to do.

drifter5

What about Whiteline springs?

From what I have research, these will work fine with Tokico D-Spec as they are right below the valve cap.

Stiffest? No, but these will work with OTS Koni and D-spec, they are linear, and offer a moderate drop.

Whiteline 350Z linear springs (control)
Front: Part # 73219,
Spring rate 365 LBS Drop: .8"-1"
Rear: Part # 73220
Spring rate 445LBS Drop: 1"-1.2"
(sold as 2 front springs and 2 rear springs)

There is a dealer on the board that sells 'em over in Marketplace.

Slow*Jim

iTrader: (5)

At this point it doesn't seem like I can get a very high quality setup for under $1600... KW V2's were on my radar before I saw what Gsedan35 had to say about them.

Would Cuscco Zero2's do well with R-comps?

z-u-later

iTrader: (43)

Really? You're obviously ignorant about tracking cars. I don't think you've even stepped foot in an autocross course, much less a road course. NEVER lost it in a road course, unlike someone you know. Check your facts next time. Knocking down cones ain't nothing new to someone who pushes it to the limit. You obviously wouldn't know.

SOLO-350Z

iTrader: (26)

Seems Ed never learned. Looks to me you got banned.

thinking

iTrader: (4)

Curious.
What was the fellow Z owner (that you quoted) running on his own car?

Also, from what I have read (no personal experience), 525-550 lb/ft front and 500-525 lb/ft rear combination are about the highest rates that should be run at the track on the 350z. Anything higher has negative effects (possibly limited to all the koni-based setups including custom valved).
Have you found something different?

Gsedan35

iTrader: (10)

Do not use progressive springs on a car intented for the track,......period. I will front and center not recommend them for a car you'll drive anyplace aggressively either. For your intended purpose, for what you want to do it is a compromise that fly's in the face of what you want and cost you the very things your trying to accomplish in modifying the suspension.

If you want 392lbs front and 448lbs rear, you can do it just like I did, only thing you'll need to add to have a 1.2" drop in the front is to spend a few dollars with Koni shop services. You would have them do a simple mod to the front Koni shocks, have them cut out a 5/8" section from the lower leg of the shock just above the lower mount and reweld.
OTS Koni yellows $800 new or $400 used
Tein tapered springs 392lbs $120
6061 machined lower spring seats (front) $25 and your time
Tom's Motorsports adjustable rear spring seats $160
Eibach or hypercoil 5.5" outside diameter springs 9.5" tall 448lbs $125

Gsedan35

iTrader: (10)

I'll pm you about what the setup was. I didn't want to say too much in quoting a private pm conversation.

On the topic of peak spring rates and what any one should or should not use, from a post I did on another board.

What spring rates to run ultimately comes down the math being right AND proving the math with actualy testing. The following give's some insight to a winning Grand-Am teams testing on the 350Z in terms of spring rates.

The following quotes comes from a interview of the owner of Unitech Racing Jackson Stewart, the crew chief for the 350Z Grand-Am team Jeff Wisener and the owner of Perfomance Nissan, Michael Cronin.

SZM: "I noticed a trend that many Z owners are putting coil-over suspension systems on their cars, but you mentioned today on the track that many people are putting too stiff a suspensin and actually making the car handle less effectively. Is that true and can you comment on that again, please?"

Stewart: "Yes, it is absolutely true. Most of the aftermarket suspensions sold for the car are way too stiff. More often then not, for actual track performance, a lot of upgrades are hurting the performance of the car."

Cronin: "The common perception is you don't want a car to sway in turns, squat during acceleration, or dive during bracking, but those are things you need to have the car do to handle correctly."

SMZ: When setting up your race cars, did you use or try any of the common aftermarket suspension kits that are avaliable?"

Stewart: We looked at then in a sense that we wanted to know what was out there, but we also had gone through a range of springs on the car and if we went siffer, we lost performace. We have a range of a few poinds we use in the rear to make it oversteer or understeer. So if we see a spring someone is running on the street that is 50 percent stiffer, they are losing overall performance." {His use of the 50% number is a somewhat ironic number to toss out given that 314lbs upped 50% is 471lbs and yet they went with 525lbs or +67% in the front. Unitech did the R&D for the Truechoice 350Z coilover system and that setup uses 525/425 spring rates}.

JohnnyHT

iTrader: (2)

Re: the T2's...NISMO "claims" they can be used with the stock shocks...any truth to this statement? (albiet ANY spring can be used with stocks but it's only a matter of time before failure)

r_seng

iTrader: (9)

I ran the Swift Spec-R, I would recommend them to anyone for a track set-up.

Gsedan35

iTrader: (10)

Note that the two springs are almost identical in rate and drop.

Swift 350Z Spec-R progressive springs 1.2”/1”
Spring rates in LBS intial/final Front: 291/392 Rear: 280/448


Eibach 350Z progressive springs 1”/1”
Spring rates in LBS initial/final front 296/384 initial/final rear 316/421