kilogram

iTrader: (1)

Right, but what I'm saying is we don't know which "progressive" springs are actually coil bound at ride height. Coil bound means the progressive coils are stacked against each other and taken out of the spring rate equation, as they're no longer active coils. That leaves only the linear portion of the spring as active. Swift does this. It's technically a progressive spring, as it has two distinct spring rates wound into the spring, but the progressive section becomes coil bound at normal ride height only the linear portion of the spring is active, making it a linear spring.

Voodoo Club

I'm glad you really like this setup.. Definitely thinking about getting a similar setup (tein springs). Thanks for sharing!

Z1NONLY

iTrader: (2)

Basically just an integrated helper spring. (So that it stays in contact with the the mounting points when unloaded)

kilogram

iTrader: (1)

Exactly.

zerofighter

Im still trying to wrap my head around why people are choosing tein for performance gains. From the numbers it looks like the fronts are a hair stiffer than stock, and the rears are softer than OEM. On top of the lower spring rates you're lowering the vehicle. Im sure the car rides nice but I dont see it being a performance setup... at all. Ive been talking to a few guys at the Nissan challenge, and based on what people and shops are telling me, the Swift Spec R have been a good contender on OEM shocks vs guys on coilovers, and based on reviews the springs are comfortable.

RobPhoboS

All I can say is I'm very happy with them, I tried them on stock 2004 shocks, then when the B6's arrived.
I'm not timing myself or whatever for track days, just spirited driving and they feel far better to me than the stock ones. That's all that matters for myself.

Spike100

I wouldn’t necessarily equate stiff springs with better handling, or assume that softer springs compromise a performance setup. Matching compatible springs and shock absorbers is more important. Sway bar selection is also important.

Google “Big Bar Soft Spring Setup” to read about some setups that debunk some handling myths.

MicVelo

Spike is 100% correct.

There's a lot of different set ups that work better for particular cars and not all of them involve stiffer-than-stock springs.

Take for example, older BMWs (not sure how the newer ones are set up). Back in the day, the German engineering tuning firms (particularly Alpina) loved to set up their cars with extremely stiff springs but lighter damping shocks to let the springs do most of the work of chassis leveling.

But then, you take a different type of suspension like the early Z (S30) with four way independent Macphersons at each corner and the hot tip there was lighter springs with very stiff shocks (as offered by Datsun Competition).

Point is, a lot depends on the type of suspension being used; as the two examples above illustrate somewhat different configurations but both with very positive end results.

Based on what Nissan engineered into the Z33 and its particular suspension configuration (Strut front, multi-link spring independent rear), it's very possible that a softer set of springs in conjunction with a stiff (or adjustable) shock is the best compromise for a street driven car.

I'll find out in a few hours. Heh heh.

zerofighter

I appreciate the feedback. I'm definitely not saying that you're doing your car wrong. Im sorry if I came off that way. Im just curious as to what the reason why people went with tein aside from the price point.

zerofighter

Big Bar soft spring is a term that was used in circle track racing which may have transferred over to road racing. I have no idea who would ever run such a setup. It is very effective for round racers because it allows the racer to use a really soft left front spring and uses the bar to apply the load, it keeps the front left nose down when the forces are applied to the right corners (which is obviously the only side that ever sees load). This is done for aero purposes. There is a wide variety of ways people race on these setups, but almost all of them will have something to stop chassis from bottoming out, whether it be a rated bumpstop, or run on a coilbind. If it is run on a fully sprung setup, the setup is changed per track, due to speeds, banking, the sharpness of the corners, they dont want to drag frames. Nascar is a perfectly good example, when they race they run big bar soft springs. But when they race on the road race track, the spring rates are bumped up significantly.

A sway bar is pretty basic, it increases the rate when the opposite side is loaded up just like a spring would. But the wheel rate would be softer cruising in a straight line where no load a single side is seen. Actually a proper race car would use minimal sway bars just to limit inside droop when making a corner. Ultimately a sway bar increases spring rate around a corner at the cost of mechanical grip.

The bilstein shock being a performance shock, means they would probably add more valving to the shock especially compared to OEM. Which means that chances are if you run a softer rear spring than the OEM then you would be overdamped moreso than with the OEM spring.

I cant really agree with you on sway bar selection being more important. All swaybars I can find list the bar diameter and whether or not they are hallow, but what does the bar diameter mean to you? I'm pretty sure 99% of the users is unable to quantify the actual bar diameter into load numbers. You would have to measure out the arm length as well as the overall length and then diameter to figure out the proper sway bar rate. And then after that you would have to figure out the motion ratios of the sway bars to our chassis. When it comes to springs we can find out the exact rates that is going onto our cars.

zerofighter

The spring rates are relative to the way the suspension is designed. The spring is what holds the car up period. It is never the shock that does it.

BMW's have always had a similar setup rear suspension as the Z. Which is the reason why they need such high spring rates. In fact most cars even today run about 600lb springs in the rear from the factory, but even with these spring rates the wheel rates are softer, and the shock is located closer to the rear hubs making the valving of the shocks a lot softer.

A macpherson on the older Z on the other hand is attached right at the hubs. So the spring rates translate straight to the wheels, hence the reason the spring rates are softer, and the shock valving not very much different from the BMW's being close to the wheel like each other. If you were to look at the numbers in each shock valving to spring rate in relation to each other they might seem like very different setups but its actually properly matched for the chassis design. There is only one critical damping number to any setup its up to the manufacturer to decide how close to critical they want to get.

And then of course they can run a bar to make the car more comfortable on a daily drive, without hindering the performance too much.

There is no force in a shock, all it does it dampen the spring. In fact if you look at the suspension setup on the 350Z, the supposed high spring rates of the Swift springs arent even considered that high. In fact if you just look at the rear wheels its only a 206lbs, The tein is about 180lbs and the stock is 190. The Z being close to 1000lb corner weight with maybe a 100lb unsprung all of these are still considered light spring rates. Its just the way I see it, you are better off running swifts rates especially if you are lowering your car. If you sacrifice shock travel, you want a spring that would hold up more weight. Sacrificing travel and then allowing more movement in the shock because of softer spring rates doesn't really make much sense to me.

Spike100

Thank you for your reply and contributing to the discussion. You obviously put significant effort into your response.

I must say that my enjoyment of the Tein S-Tech Springs and Bilstein B8 Shocks combination increases each time I drive the car. This is a great setup for street driving. It’s very comfortable while still providing excellent handling in a street environment. It is superior to the stock OEM setup.

I installed all the upgrades at once (springs, shocks and sway bars) making it impossible to comment on improvements provided by individual components.

zerofighter

LOL sharing info is what forums are all about. What kind of sway bar are you running? I can see how it may be comfortable.
I'm still up in the air about how I want to do up my suspension on my Z. I definitely do not want to run coilovers, so those are ruled out. If I can find reasons why Tein's are the way to go, I may take the jump.

Performance increase but comfortable enough to daily is my current goal.

Spike100

I’m the OP and the parts I installed are detailed in my original message (#1) in this thread.

I installed Nismo (JDM) Front and Rear Sway Bars (Stabilizer Bars) Part Number: 54600-RSZ30US. There was no specific reason I selected this sway bar other than it was a component in the original Nismo S-Tune Suspension Setup for the 350z.

I was initially interested in the Nismo S-Tune Suspension components but did not buy the JDM shocks and springs due to unavailability. Instead I decided to select components with similar specifications from other manufacturers. The Tein S-Tech springs and Bilstein B8 shocks were fairly close, and that is the reason for my selection.

I agree with your decision avoiding coilovers. There is no reason to spent that amount (and add to the cost buying additional components) unless you are a serious track driver.

Extreme Dimensions

iTrader: (7)

That sounds like an excellent setup.

MicVelo

Exactly my point. Didn't mean to infer that the shocks are doing anything more. Just saying (and agreeing with your excellent points) that for every different type of suspension system out there, there is an optimum set up for every different purpose. Sometimes softer, sometimes more stiffly sprung. Of course that's very generic.

That's exactly the reason I don't feel the need to try and modify the engineering specs Nissan designed (as far as mounting points and geometry of the suspension) by running anything other than a conventional shock/spring setup.

And I love my set up. heh heh.

I just learned a lot from your post by the way. Thought I had it pretty dialed in but you brought up some points I'd not thought about in a long time or thought through. Cool stuff, thanks.

Mic

DarkZ03

iTrader: (11)

How close are the S-tune and Tein springs really? I remember someone took the S-tune kit and changed out the rear spring because he did not like the ride, I have to say that my car does feel a lot stiffer than stock, so much that I am glad I did not go with coilovers. The thing is I did a bunch of my stuff at the same time so its hard to say if the stiffness came from just the S-tune kit or a combo of suspension and bushings. I did have quite a few torn/worn bushings so my car was sagging and had more "give" so to speak.

DarkZ03

iTrader: (11)

I do believe most of the very popular spring kits for this car are softer in the rear, I think it was to deal with the whole "bouncy ride complaint" of the early model 350Zs.

zerofighter

I agree with you. The Z came pretty well built from the factory. I have taken the car to the track completely stock with Falken Ziex 912 (225F/245R) once already and I couldn't ask for more out of the box. The car is very responsive and takes corner very well. The only issues I had was the fact that the VLSD seems very weak. I do not know if that is just the characteristics of the LSD, or if mine is worn out. The car pitches exactly the way it should around a corner and throttles out well, ultimately its a fun car to drive.

The reason why I am looking to do a suspension upgrade is because I will be running wheels and stickier/wider street tires (dunlop Z2) as well as the fact that I want to lower my car tastefully and effectively. The issue with the OEM springs is that it rolls way too much, in fact high speed cornering, the car feels somewhat unsafe because it starts floating around. I feel that lowering the car will give it more confidence because of the lower center of gravity will keep the car and of course the higher rates to resist roll and handle better tires. I believe that the higher rates will also allow my lsd to work better because there wouldn't be such a high weight shift around a corner.

I am looking to do this but keep the car a complete daily driver. I have no plans to put on an exhaust or any other mods. Just wheels, a set of performance lowering springs, and the Bilsteins.

I almost forgot... and an oil cooler. I definitely saw the oil pressure dropping as temps rose. I love the stock gauge cluster.

zerofighter

First I wanted to say that the rear spring rates are stiffer than the fronts from the factory, and again there is a good reason for doing so. The rears of the car is has the springs set further in board than the shock, which means there is a lot more leverage put onto that spring. Having softer rates in the rear compared to the front, is not something that would be recommended for performance nor would it be for comfort, because your front and rear would be bouncing at completely different frequencies. That being said, hey, to each his own, suspension feel is completely subjective. So there is no such thing as one perfect setup for everyone. If it's the way someone likes it then his mission is accomplished.

Well the S-tune springs are definitely stiffer than stock at 504lbs, but the spring is a progressive spring. I do not know what kind of bounce people are referring to, but I am not a fan of progressive springs period. No car has the same corner weights. Running a progressive spring means you are running a different spring rate on each corner. A shocks valving doesn't really change, you can see where the issues of inconsistencies can come from.

I wont know what kind of bounce people are referring to so I cant really help there. But as long as the shocks are valved tighter than stock, and I run spec R I don't for see any bounce unless the shock is bottoming out. I guess bushing can cause it because that is an undampened movement in the suspension. Again I dont have enough experience with this car so I will work on it as I go.