After a long time trying to decide between the Nismo s-tune coilovers and the common Koni/Ground control, I chose the easier and cheaper, yet less well known route. Since I use my car throughout the year in all conditions, I don't need adjustability or care about corner weights and such. Actually I do, but at my level of driving skill I just need a decent setup and lots of seat time. Also, I don't want to spend money correcting the problems with lowering the car.

There's very little info about the Nismo set. I know rico05 has been using them on his s13 with positive reviews. Here's his impression http://texasnissans.com/tx/for...=2099.

The nismo stuff was supposed to be simple plug and play, but I got them in a huge box full of disassembled pieces. Assembly was cake though. Just like stock. Of course installation was also straightforward.

I won't comment much on the look, they seem sturdy enough to last at least 2 years through snow and salt. The bumpstops design is different from stock; the front ones are a bit shorter to maintain shock travel. Specs for s14:Front spring rate: 5.3kg/mm (297lb/in). Drop: 25mm (1")Rear spring rate: 4.5kg/mm (251lb/in). Drop: 15mm (0.6")

After installing and settling in, the front actually dropped about 30mm, a bit more than I wanted. The rear matched the specs. Shock travel before touching bumpstops is about 40mm (1.5") front, 50mm (2") rear, coarsely measured by fingering the shaft

The fact that each spring actually has 2 rates (see the closely wound coils at the top?) should help rear traction. Everyone has heard of stiffly sprung 240sx pick up the inner rear tire during hard cornering.

Now onto driving impression. After riding my stock SE suspension for 4 months (stock front struts, KYB GR2 rear struts), the Nismo's don't feel that much different going over bumps. The ride is quite comfortable but everything is tight, unlike that loosey stock feel. Body roll is definitely less, but not race car-like flat. During fast swerves, the transition is smooth and settles very quickly, no more left-right rocking.

I finally got to test it last weekend at autocross. I had stock front sway bar, no rear bar, and Falken RT615 tires. Weight transition is smooth. Shock travel doesn't seem to bad, but i definitely felt the bumpstops working, especially when hitting a dip/bump while cornering. Front roll is still way too much for this kind of driving on Macpherson struts, so my next mod will be a fat front sway bar to reduce the understeer.

Driving off the autox site, with tire pressure back to normal, the ride is all comfy again. I still think Nismo lied about the spring rates. These springs are supposed to be twice as stiff as stock, but don't feel any different.

I'm quite happy with this compromised setup. Even if it doesn't fight body roll and corner as fast as I want, it serves well for how I use the car.

Here's the kind of body roll I'm getting

Some more install pics:
Modified by hai1206vn at 12:23 AM 4/29/2009

With a 25mm front bar, and 27mm rear, my car feels much more taught than stock. Wait until you get those bars on man. It will make a huge difference.

For reference, when I installed mine the first time I had an upgraded rear sway bar and upgraded/new endlinks all around.

so would you recommend those for daily driving?

Sounds like my eibach sportline/kyb AGX setup on my old s13.

The springs were rated at 2x the factory ones, and the struts were adjustable. Which helped quite a bit in dialing out understeer when autoxing.

Contrary to what Rico talked to agx about, I found mine were valved too stiff for my sportline springs. I wanted to try the stiffest ebay springs i could get but meh. On full stiff the rear would kind of "crash" or "thump" over bumps and the front would just feel mildly stiffer then full soft.

I had crazy amounts of body roll, and it drove me nuts. Too much wheel gap too. At the time I wasn't too crazy about stupid low cars, but even then it had way to much wheel gap for me.

I bought some used cusco type zeros and I love them. Stiff but my s13 is more twords a track car for now. I have a maxima to drive for a nice ride.

Ideally Id want them revalved with like 6K/7K springs F/R or R/F Im not sure, and soft valving at low piston speeds and harder valving at higher speeds. I rode in a wrx wagon that had tien ~9K F/R coils and it felt great.

So with a lighter car like ours I think around 6-7K springs AND PROPER VALVING would yeild a nice ride and good performance.

If I were you I would have gone with the konis probably.

~Alex

sil80_chris wrote:so would you recommend those for daily driving?

I have no complaint regarding daily driving on these

RustspecS13 wrote:Sounds like my eibach sportline/kyb AGX setup on my old s13.

The springs were rated at 2x the factory ones, and the struts were adjustable. Which helped quite a bit in dialing out understeer when autoxing.

I had crazy amounts of body roll, and it drove me nuts. Too much wheel gap too. At the time I wasn't too crazy about stupid low cars, but even then it had way to much wheel gap for me.

I could care less about wheel gap as long as the car owns the road. AFAIK, the eibach sportlines are progressive and lower quite a fair amount, too much for the stock design (about 2" front, 1.5" rear, that means the front is already sitting on the bumpstop at rest). With progressive rate that ranges from 120lb/in to 234lb/in in the front, that definitely increases the front body roll. I'm not sure, but the nismo springs should be linear, don't drop too much to screw up travel, and the shocks are matched

RustspecS13 wrote:If I were you I would have gone with the konis probably.

~Alex

I wouldnt be at all surprised if the Nismo struts were Konis.

FlatBlackIan wrote:I wouldnt be at all surprised if the Nismo struts were Konis.

Nope. These struts are made by KYB to Nismo specs

As an extra note, I think many of us really under-use sway bars. They are great for dealing with body roll without going with ridiculously high spring rates, if you need to drive on the street. Although I've never had an aftermarket sway bar, I really believe things will change dramatically after such upgrade.

hai1206vn wrote:Nope. These struts are made by KYB to Nismo specs

Would have been my second guess, followed by Bilstien.

hai1206vn wrote:As an extra note, I think many of us really under-use sway bars. They are great for dealing with body roll without going with ridiculously high spring rates, if you need to drive on the street. Although I've never had an aftermarket sway bar, I really believe things will change dramatically after such upgrade.

A very good point. Ive been meaning to get a hold of a new front sway bar for a long time. I was impressed by how big an improvement I felt just switching to poly endlinks.

Another overlooked thing is bushings. Doing a full bushing kit is a very daunting task, but the improvements are incredible. As far as suspension mods go, my ES bushings are likely my favourite.

hai1206vn wrote:
I could care less about wheel gap as long as the car owns the road. AFAIK, the eibach sportlines are progressive and lower quite a fair amount, too much for the stock design (about 2" front, 1.5" rear, that means the front is already sitting on the bumpstop at rest). With progressive rate that ranges from 120lb/in to 234lb/in in the front, that definitely increases the front body roll. I'm not sure, but the nismo springs should be linear, don't drop too much to screw up travel, and the shocks are matched

They are rated at that much drop, but it ended up being 1.5 F/1.2 R. Like you I would have been happy with the results if it "owned the road" but it didn't.

Your springs are progressive as well. All the coils would be the same length/diameter if they were linear.

hai1206vn wrote:The fact that each spring actually has 2 rates (see the closely wound coils at the top?) should help rear traction.

How can that be linear?

Im not arguing just discussing.

I do agree with the sway bar comment. Ive always had other things to buy. Especially on my old hatch that had the kyb/eibachs in the first place....

RustspecS13 wrote:Your springs are progressive as well. All the coils would be the same length/diameter if they were linear.

How can that be linear?

I think progressive rate is not the same as 2 linear rates combined. If you look at, say Stance GR+ Pro, the helper spring on the rear is of a lower rate. On the Nismo's, there seem to be 2 distinct parts on the same spring. So it's likely that the Nismo springs behave like having 2 linear rates.

On such setups with 2 rates, the helper (weaker, shorter) spring doesn't actually contribute to the effective rate, because the static weight compresses the helper springs such that they fully collapse and bind, leaving the main spring doing the work when the car moves. The helper springs are only useful when the main spring is fully extended (like when you jack the car up, going up a driveway, or when the weight transfer/body roll is enough to pick up that corner). That extra force from the helper springs keep some weight on the wheel, giving it some more traction

hai1206vn wrote:I think progressive rate is not the same as 2 linear rates combined. If you look at, say Stance GR+ Pro, the helper spring on the rear is of a lower rate. On the Nismo's, there seem to be 2 distinct parts on the same spring. So it's likely that the Nismo springs behave like having 2 linear rates.

On such setups with 2 rates, the helper (weaker, shorter) spring doesn't actually contribute to the effective rate, because the static weight compresses the helper springs such that they fully collapse and bind, leaving the main spring doing the work when the car moves. The helper springs are only useful when the main spring is fully extended (like when you jack the car up, going up a driveway, or when the weight transfer/body roll is enough to pick up that corner). That extra force from the helper springs keep some weight on the wheel, giving it some more traction

That is what progressive means. Under certain circumstances the springs progress from one rate to another. They are progressive rate springs.

Its very common to see progressive rate lowering springs. They allow the car to sit low while using stock length dampers, while at the same giving enough spring extension to stay preloaded on the damper.

It also means you can use a factory length damper, with low ride height, and still have a decently stiff primary spring rate.

Hmmm i always thought that a progressive spring transition continuously from rate to another rate as it's compressed. Whereas in this case there are 2 rates (that's my assumption from how the springs look, not a fact).

In my pic below, when on the car at rest, the low rate part of the spring completely binds and contributes nothing to the overall spring, so only the higher rate part is effective. Which means 1 effective rate, so it can't be progressive.

That is how progressively wound springs work.

I have seen hundreds of progressive coils, they all look like the nismo springs.

Here's some info i found about springs http://www.tuninglinx.com/html....html. According to this source, the Nismo springs should be 2-step linear springs.

i see what you mean. But by your description, wouldn't the rear springs on these GR+ Pro be considered progressive?
Modified by hai1206vn at 11:47 AM 4/29/2009

In some markets yes, you can refer to 2 step springs as such, but for all intents and purposes they are progressive in the fact that they progress from one rate to another. I have seen the Nismo springs advertised as progressive rate, as well as many other 2 step springs.

Using the term progressive is like using the term forced induction its a cover all word. Truely progressively wound coils are kind of rare.

The stance coils are linear, with a helper spring. Using a progressive (or 2 step) coil with a helper spring would be stupid, as they are both designed to do the same thing (increase droop travel).

gotcha.

i was just saying the linear spring + helper spring setup on the GR+ Pro is essentially the same as a 2 step linear spring

hai1206vn wrote:gotcha.

i was just saying the linear spring + helper spring setup on the GR+ Pro is essentially the same as a 2 step linear spring

Thats true, though the helper springs are usually an extremely light spring rate. The last set of Tanabe's I had apart, I could compress the helper springs with my hands. Although when I changed springs on my buddies HotBits rally coilovers, his helper springs were very stiff.

Got some more testing with these. I decided that the car was understeering too much and put the stock rear sway bar back on. Last week's autox course was tight. My setup turned out to be terrible. The car would just plow straight ahead due to massive front dive, and then when I tried to add gas to get it to turn it would understeer even more, until the tail snapped loose. The front tires were totally uncontrollable: they didn't squeal at the limit, didn't fight back, but slid straight ahead by themselves no matter how the steering wheel was turned. After each lap, i could feel by HAND the outer side of my front tires warmer than the inside - like i was using only half the tire.

Lesson 1: Nismo front springs aren't stiff enough to control roll

So I got home totally disappointed and went on ebay to buy a Progress front sway bar that I'd been looking at for a while. It came and got installed today. I set it only at the softest setting to begin with and drove straight to an empty parking lot for some tight turns.

Wow what a difference! Still a slight amount of understeer at the limit, but the car is so much more controllable. The front end would just keep turning, and at the limit started to squeal and give out gradually. Very close to neutral I felt.

Lesson 2: Big front bar has a much more significant effect than stiffer springs

Of course the car still rolls - it's not a race car. But it does so in a more balanced manner front-to-back, resulting in more neutral handling (still toward understeer for now). This weekend the setup will be put to test. I'll also try a stiffer setting on the bar.

After 3 weeks on the Nismo "coilovers", I'd say they are decent, and the shocks are certainly well matched. The ride is firm yet comfortable. However, they are a compromise and need some addition for performance driving.

I'm pretty sure a spring&shock combo (springs should be as stiff as Nismo or RSR Race) plus a fat front sway bar is the way to go for a street 240.