I think that the RS*Rs or the Espelirs are a good choice for auto-x (maybe they are even too soft). I like a stiff car, and to me, I would like even a stiffer track spring (like the T2s, which I would get if my Tokicos could handle the spring rate).

I have an auto-x this weekend on the Espelirs, and I'll let you know how they perform.

As far as finding a linear spring that isn't "too stiff," I guess that depends on your definition of "stiff." IMHO, neither the RS*R or Espelirs are too stiff.

 

too stiff is anything above a 500 rate.

want something in the 400 area.

 

PMd you also to find out what you think of the Espelir Active GT springs during your auto-x. I'm debating between this and the RSR springs. Looking to pair them with Koni yellows.

 

FYI... coil overs are not Street Prepared legal on the rear of the 350Z. You have to run a separate spring and shock combination similar to what the DSP E36 BMWs run.

Also, autocross cars tend to run higher spring rates then track cars. A good starting point for a "to the limit" BSP 350Z would be the Nissan T2 springs at 690 lb. in. per corner. I would think something like 850 front and 700 rear would be an ideal setup for a BSP 350Z, but that's just a guesstimate with no math or testing to back it up.

 

You would need something other than the Tokico D-Spec shocks for these springs (per Tokico, these are only good to about 450 lb/in.). Plus, you may not want to drive this car on the street with those spring rates! Almost needs to be a dedicated track/auto-x car with springs that stiff.

 

A "to the limit" Street Prepared car is not driveable on the street. They are trailer queens - mostly because of the 5.25" OD multi-disc clutch.

 

have you guys checked the date of this thread???

 

It's still relevant. As you can see from the debate, this is an issue all of us have to deal with at some point, and there is no single "right" answer. I am still researching also, to the point that I am probably going to continue putting off the decision until more people chime in with their "winning" combinations.
It's funny how certain threads keep renewing themselves, like the trailer hitch thread, for example. Steve, what did you end up with? The Toms or the Espeliers? I forgot what you said in December. Was one good for both autocross and track?

 

I have both, but I use the Toms for track work. The Espelirs are progressive, and softer, so they are better for street use. I am quite happy with the Tom springs, especially since they are height adjustable. You rode in the car at BW, John - what did you think?

If you are using the car as a daily driver, I would definitely suggest the Espelirs. But if you want a better track set-up and can stand the harsh street ride (500 lb/in), get the Toms.

 

With all your aero parts, it would be hard to judge the suspension alone in a ridealong- too many variables. So the Tom's are too stiff for daily driving, then. So are the T2's. We're looking at 400-500 lb/in springs then for street/track. Anyone know what that translates to in kg/mm for Japanese parts? And my other question is this- is it better to have stiffer fronts or rears? Nissan seems to think the rear should be stiffer, but all the Japanese tuners have the front set stiffer.

 

Lately I've been running stiffer front and softer rear when I setup RWD cars. The idea is to improve power application in the turn. To keep understeer under control I try to increase front track width as much as possbile, run expensive shocks with some kind of adjustable slow compression valving, and keep the front ARB as small as possible.

 

Does Ground Control make coil sleeves for the z? You can get springs in 25# incraments on the springs. I'd go like 425/500 with the konis.

Have you completely eliminated the thought of getting a true coilover set?

 

So you believe the smaller front ARB and wider front width make up for the added understeer? Interesting.

 

That and equal sized tires all aorund and shocks with a third adjustment for low speed compression.

 

I agree that equal sized tires all around generally makes for a more balanced car in the case of the Z. There are a lot of threads which discuss this...

3-way (or even 4-way) adjustable shocks are not cheap though, and for me, they are not legal (any more) for Street Class in the time attacks that I compete in. (There is always something that gets you!)

I like the Toms since they are 500 lb/in all around. Again, if the car is weight balanced (50/50 or so front/rear), I think a balance of spring rate is also appropriate. But if I had a choice, I would actually like slightly more front spring (maybe 550 lb/in), for exactly the reason that you describe, Beta. I am actually looking for some springs in this rate for the front that will fit the Tom perches.

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500 lb/in is about 9kgf/mm, John. Here is a "quick and dirty" table to help you:

12kgf/mm=671lbs/in
11kgf/mm=615lbs/in
10kgf/mm=559lbs/in
9kgf/mm=503lbs/in
8kgf/mm=447lbs/in
7kgf/mm=391lbs/in
6kgf/mm=335lbs/in

 

Ground control made one set for the Z, but decided that fighting to make a easy to adjust rear height sytem was not worth the effort for production. That one set ended up on ebay, I emailed the seller, setup had something of the order of 600lbs springs.

You can make your own front coilover setup like I did by raiding the Koni motorsport's catalog, they have sleave coilover parts. To address the issue top mounts I used Tein tapered springs which allowed me to reuse the oem upper mounts, I fabbed a adaptor out of 6061 aluminum to convert the 70mm ID to seat on the 65 ID Koni mount. Even at 448lbs in rate, I kept on running out of bump travel, so I sold the Koni's. BcRacing can sell you a front upper pillowball mount and they can sell their rear spring adjustment system. Without shocks that have shorter bodies and piston rod lengths, I wouldn't bother.

 

Agreed. Though I take your giving the advice on the small ARB to quell the same issues that require addition rebound control with greater and greater level's of ARB stiffness.

 

You forgot how he's running more front spring rate. The idea is the same as running more front ARB (the plus being less camber change on braking vs stiffer ARB only). Leverage more to the front tires to keep their front contact patches in the game. Tires that roll over and play dead can't contribute.

 

Have you talked to truechoice yet? It sounds like they can get you what you need. I've been very happy with mine for the 2 years that I've had them. I also have the luxury of changing the springs to any rate I desire since it uses off the shelf Hyperco (or eibach) race springs.
I'm glad I waited over a year for them to be released rather than trying to piece together setups like some people are posting here. Not saying that you can't build your own and be fast, but it was nice to have the pros put it together so it was right the first time. Probably cost me less in the long run too.

 

Well, I'm glad I'm on my way with the tire sizes... now the shocks, where can you get those?