-Yes, I have read suspension 101 plus a ton of other threads/stickies about these shocks/springs combos. I've spent about 2 months researching this and these questions are the culmination of my research so mods please don't close this.

So, I bought a mint '04 touring 6 spd with 34,500 mi in April 2012. It is now October and the mod bug has got me. I've already bought some 18x9.5+15 and 18x10.5+15 rpf1s with 265/35 and 285/35 hankook ventus tires. Now I want to modify the suspension. My goals are:

1) reduce understeer to create a more balanced car without increasing the tendency for snap oversteer/ruining the factory chassis balance.

2) Lower the car no more than 3/4", in order to hopefully avoid needing front camber arms and because roads are absolute **** in indiana. From what I've seen from people's alignment specs though, even with springs that give camber within factory specs the camber is often uneven. I don't know if this is due to age of suspension, e.g. worn bushings, etc. or just happens with the 350z. If so, then I'll need camber arms anyway to make both sides match. Guess I'll only know after the alignment.

3) Use the oem shocks and struts, if possible, at least until they go out, since they only have currently 36,500 miles on them. After they go out I plan to upgrade to D specs, so ideally I want a spring that can work with the oem shocks at first with a little sacrifice in ride quality, but can also take full advantage of the d spec shocks and not have to get new springs for the new shocks later on, because by that time I'll have spent enough for V1 coilovers. I know it's a lot to ask for a spring and that's why people get coilovers, but just wondering if it's possible.

4)Have a suspension set up for daily driving comfort, but can also be adequate for light auto crossing or tracking.

Notes:

-I've weighed the options of coilovers vs. shocks/springs and I feel that I can get better performance out of a d spec/spring combo than cheap tein or meagan, etc. coilovers. I've found I can find a used d spec/spring combo for around $600-700, compared to the next best entry level quality coilover kw v1/eibach pro (same kit) which goes for $1000+ and has no damper adjustability. So don't tell me just to save my $ to get coilovers.

-The first mod I plan on getting are hotchkis adj. sway bars since this seems to be hands down the best suspension mod. Why hotchkis? 1) They are cheap. 2) from what I've read there are no major failings in quality. 3) They are adjustable (biggest reason) 4) I've read they are still fairly lightweight (I think they are hollow? could someone confirm this?)

So, my overall question is: What are the best springs to meet the above 4 criteria?
(Note: all spring data are from this site, and based on the unrevised suspension. I also plan on doing the rear spring mount mod to drop the back an extra .5")

I have narrowed my options down to these 3...

1st option: Swift Sport linear springs .8”/.6” drop
Spring rates in LBS 336/364
+7% front +6.4% rear, overall roll stiffness remains basically stock

Pros: From what I've read these seem to be the best choice since they were designed for the unrevised shocks and are linear. Also, I'm leaning towards a linear spring as opposed to a progressive one for predictability, ease of tuning (since I can base it on predictable linear spring rate), and because thats what the factory springs are and I'm using them with oem shocks.

Cons: they are hard to find used and are expensive new. For $300 for springs + $600 for D specs I could get the KW V1s. However, if I could find them used this might be the best option. Also, the front drops .8" which is right on the border line for needing front camber arms.

Questions:

1) I just want to know if they would work as well with the D specs as the RSR ti 2000s have been known to, or are they not stiff enough?

2) They also don't seem to put any more net roll stiffness to the rear, but don't add any net to the front, either. So will this result in a more balanced spring package along with the sway bars?

2nd option: RSR linear springs .6”/.6” drop.
Spring rates in LBS 345/417
+ 10% front + 22% rear, overall roll stiffness moved 12% to rear.

Pros: I think these would be good for helping to balance the car by moving roll stiffness to the rear, thus less understeer. Only .6 inch drop, so unlikely to need front camber arms and can spend the $ on new shocks instead. They are made with titanium, so are slightly lighter. This may not really matter for what I want to achieve though. Then again, reducing unsprung weight is about the best handling mod you can do.

Cons: My concern is that with the oem unrevised shocks plus my large staggered wheels and tires, will I now have oversteer problems? I have read these sometimes lead to oversteer issues but that they are fixed with the adj. sways. Others absolutely love them to begin with. My other concern is that these will be too stiff for DD, as I have read people complaining about stiffness with pro kit and s techs, which have a lower and progressive spring rate. This is hard to say though since ride harshness is subjective. These are also hard to find used, and fairly expensive new as well.

I'm thinking these are what I will go with. There are a lot of reviews of people liking them with the D specs. I just don't know how they are with the oem unrevised shocks. They seem like they would go well with the revised shocks since the spring rates in rear are similar, but idk about the unrevised.


Questions: Could anyone give me an idea how they are with the unrevised shocks? Too stiff, too bouncy, shocks not valved correctly for these springs, oversteer, etc?

Option 3: Tein S-tech progressive/linear
(fronts are progressive, rears are linear) .7”/.6” drop
Spring rates in LBS 386/402 (estimated front intial rate is 327lbs)
+4%-23% front,+17.5% rear, so 13.5% to -5.5% roll stiffness to rear

Question: I have read that these are progressive front and linear rear with the front basically being linear. I have also read that these are basicly progressive front with linear rear and I have also read that the springs are generally progressive front and rear. Can someone please confirm which of these is true?

Pros: They are cheap and easy to find and good quality from what I've read (anyone disagree?). The progressive front may help reduce annoying small bumps in the road while driving. Usually don't need front A arms. My impression is that they are a good all around spring that will work well with stock unrevised shocks as well the D specs and give good ride quality with both while giving good track performance. Does someone disagree?

Cons: They are progressive. Whether or not this is a con depends on how progressive they are, so if someone could answer this that would be really helpful. The roll stiffness could be anywhere from positive to negative, so they may be fairly unpredictable.

Question: Do to the progressive nature of the front spring, is this not a good option for light tracking/autocrossing?

I know I have a lot here. I just wanted to put all the details in one place so that people can weigh the pros and cons of each spring based upon what I want to achieve with my suspension set up. If you answer the questions please copy and paste the question you are answering to avoid confusion and make it easy for others to know what question is being answered. I'm sorry if there are threads that already answer these questions, but I'm trying to have the answers all in one place and for my specific purposes. Thanks for all your help.

 

you will not have an oversteer problem. You will still have a lot of understeer to to the tire stagger. Wider rear tire = understeer, you will have to tune that out. Next if you run close to factory camber specs as you want, you still live in understeer city. To reduce understeer you need more front camber, a lot more front camber. Well out of factory spec front camber.

Hotchkiss bars are hollow, and cranking up the rear bar is the fastest way to make the car snap oversteer. I run mine full soft rear and one up from full soft front.

RSR of Swift are probably you best bet, ARK also has a couple of nice springs you should look into.

 

terrasmak, thanks for the quick reply and not hating me for the huge post. I've seen a lot of helpful information from you in other posts. Just a quick follow up to your reply. So, I understand the staggered tire setup will give me understeer no matter what. But, even with the rsr springs transferring 12% roll stiffness to the rear and proper sway bar settings, I'll still have so much understeer I can't even use close to spec front camber settings? Ideally, I'd like to be between -1.5 and -1 in front to reduce tire wear. Is my only option to switch to a square tire set up to obtain a neutral handling car? Thanks again.

 

Basic question..if I may..
Are you well versed in the handling characteristics of this car in STOCK form?
More specifically..have you tracked the car in stock condition?
If so..what are your impressions? Once we have that info..we can proceed. I'll give you one clue...watch out for oversteer ..yes OVERSTEER. Have you ever hammered this car in a turn..HARD?
BTW...My sig will provide you with some possible solutions.

 

Hammering the throttle hard out of a turn causing oversteer would be throttle induced oversteer. Even an under steering car will oversteer when you do this.

Front alignment spec is around -0.3 to -1.1 camber. The typical street car that is run in canyons i would run -1.5 to -2.5 and a more aggressive track day car -2 to -3. For the average street car -1 to -1.5 is great and will help out handling.

For now, just run the 265/285 stagger, learn the car and have fun. Set the rear sways to full soft, and use the front adjustment to add or remove front bite.

Square tire setup, very nice for autocross and track. Later on down the road, you may want to look into this as your skills progress. I neutral car is actually pretty tail happy to sommeone who is used to a understeering car, especially when they have the tendency to throttle it over.

BTW autocross and roadcourse swaybar setting seem to be really different for this car. What works on one , doesnt always seem to work for the other. The difference in high and low speed handling.

 

Re: RSR springs

You'll probably have a hard time finding these, as I believe RSR no longer offers them or something to that effect. So this option might be a dead end for you, unless you can find them in the used marketplace.

 

Well this is probably a dead thread now, but for what its worth I ended up picking up some used tokico D specs. Got a good deal, and since r-sr and swift springs are few and far between I'll probably end up going with the tein s-techs. You all have brought up good points, I should probably just get used to driving my car at the limit first before I make any drastic changes. Prob just shocks, springs, sway bars for now. I'm gonna do some track days at my local track Putnam Park this summer too. Also, here's the screen shot of one of my favorite local roads I like to drive. Just a great backcountry Indiana road.