Duh sorry, I was looking at a spreadsheet. I intend on using the SPL midlinks with spring perch on the back instead of true type like Martin. I can't decide on go with 9" then jack them up a bit or go with 10 and keep the perches low. Any recommendations on that? The perches allow 3" adjustment range:

https://www.splparts.com/store/produ...hp?pid298.html

I am figuring a 9 or 10 inch spring.

I use an OEM layout, most race springs in 2.25, 60mm and 2.5" are most readily available up to 8". It will depend on spring rate, but anything from 600-750 you will probably want a 7", 800-950 6", etc. 550 and under you might be able to run an 8".

OK, take a look at my math on this one if you don't mind:

OEM rear spring measures about 10" at ride height. Wheel rate is about 1.61, spring motion rate I am saying is about .63.

Let's assume unsprung corner weight 675 lbs. and for arguments sake a 500 lb/inch spring.

675/(500*.63) =2.13 inches of spring compression. If I use a 9" 500 lb spring. That would mean the spring is only 6.9 inches tall at ride height.

Right?

If that part is right, then the overall ride height at the spring has moved ~3 inches lower. 10(oem length) - 6.9 = ~3

3*1.61 = 4.8. So the top of the tire would come up almost 5 inches(or body would lower whichever way you want to look at it.)

Do I have a mistake in my math somewhere? I am wondering if I measured the OEM spring length at ride height correctly. Will crawl under there tomorrow, but point out any mistake I am making there.

That's all fine, but it relies on the same static spring perch height. Any decent shock is going to have a threaded perch for the spring, which you move up. You won't lose any dynamic bump travel, even with a 7" spring. There is a considerable weight savings to be had by using a 7x2.25" spring vs a 9-10" larger diameter spring as well. I want to say the rear was a 5 or 5.5" ID spring in the rear.

Too Low!
 

In fairness, you use REALLY short tires and soft springs. Your car never seemed low at static heights.

So you have coil overs mounted in OEM spring location in the rear? On a coil over I understand, but for that SPL mid link solution I think I might still need a longer spring if I don't use a true coil over.

The shocks I am considering are Koni 2812's or 2816's for the rear. Not sure I have a product selected for the fronts yet.

No. You use threaded perches same as the front, just in the spring bucket.

Ignore the excess anti-seize:
http://farm9.staticflickr.com/8380/8...63e7054a_c.jpg

Koni's.....hmmmmmm

http://www.koniracing.com/2812mk2.cfm

You mean 2817?

http://www.koniracing.com/2817.cfm

You would want 2812's for all 4. They package better than remote shocks, but are not cheaper. You will spend $4k once all is said and done for a set. If you go that route, call Jeff Wong at ProParts.

OK, but then how to build the front? Where do the spring perches go?

neither: KONI: Racing

number three, just 2812.

I went with MCS 2 way non remote. I have ast 4100s on my subaru but i would discourage anybody from buying them. I have been waiting 2 months for a shaft and they still don't know when it will be in. AST parts come from Holland. Products | Motion Control Suspension | Damper and Coilover Systems

And that picture was taken in the braking zone at the bottom of turn 4 while on cold (under inflated) 245/35/18 tires.

Things evened up as they came to temp. Then my master cylinder failed and I crashed into the oil recycling station. But that is another story...

The shock has a threaded body. The perch moves up and down on these threads. You may or may not need helper springs...depends on desired ride height, shock length and spring rate.

Ok.

Edit: o wait you guys are talking about the rear aren't you?

You talking about the spring height moving with a sleeve around the shock body, or the whole shock body moving for height! I always thought coilovers worked by adjusting the sleeve around the shock body that the spring sits on till I watched the fortune auto video about how to set up their shock and can see the whole shocks spins around the lower mounting holes. This keeps the spring always under tension. I guess in the video they talk about lesser quality coilovers only adjusting height the first way which when lowered to much won't have an tension or preload on the spring and it will flop around till the car has weight on the top hat.

Nice. But damn, Im sad to hear you're unhappy about this! My WRX was a world of difference from the OEM like 220lbs fronts and 190lbs rears to RCE yellow 330lbs all around a koni adjustables. The setup didn't break my back but dear lord did I go from some serious body roll to almost zero!! You're OEM was like 7-8k and now you're over 10k and unhappy. Hope I have better luck with my selection.

Wait, are those FA springs or swifts? Progressive or linear?

On the fortune setup, basically the preload is set independently of the height. On some of the lesser coilovers, you set the height and it would change the preload at the same time.

For the 370z, some suspension kits will modify the rear suspension to a point where they would turn the rear shock back to a "strut" type of setup with the spring sitting on a perch in the back instead of the "tub" in the back.

At the end of the day, good shocks are very good expensive. Prepare to custom build them as the 370z doesn't have a lot of options

Ok math aside, brands aside, all this techno stuff aside; I and maybe Spoon might still be confused. All I know is I have parts in mind, I have coilovers in mind, I have a spring in mind and I even have alignment settings in mind!!!

Question is though it still seems like you guys are talking about a thousand different ways to set it up like I'm doing all this buying of parts and it will be wrong. I want the Z to handle right and well and not put me into a wall.

I guess it just seemed easier on my race bike!! I had full race built adjustable forks built, a Penske rear triple clicker shock and I took my bike in to be "dynoed" or we called it computech'd where rake, height etc was all tailored to me and my weight and besides the occasional stiffen or soften on the adjustment knobs, the bike just flicked around and felt like it was on rails! I just want it to simple I guess.

The problem is that the front of our car doesn't like anything but a coil over solution. The back only likes a shock + spring solution. There are not a lot of products in the market that solve this problem.

KW V3 does the best job out of the box IMO. But they are also a bunch of A-holes on the phone. I personally wont buy 3000 dollar items from a company that puts idiots that "don't know" or "can't tell you" how their product works on the tech support line.

So you start to look to custom solutions that will allow you to actually do what you want with the suspension tuning.

Have you looked into the PSS10s? Ideally, the best would be to get a set of used one and revalved the shocks and springs, but used sets don't exist for the 370!!! Unfortnately you have no choice but to spend money on custom solutions. I thought the Fortune setup would be a good stopgap, but it just didn't work out like I hope it would.

MCS makes a decent off the shelf set-up. You can buy double, non remote shocks (package better than the remote shocks) from them for about 3300. That does not include springs, top mounts, etc.

Have you called? Maybe they'll up grade the springs for you? If OEM isn't as strong as true type then you only have like a 6k in the rear. And like said earlier, a good start would be a 18k front. Maybe try 18k front with a 15-16k rear?

That might be to stiff for our rear. Lol. Anyways due to the nature of are cars being tail happy a little softer is really needed. I'm seeing where some are removing the sway bar completely after a good Coilovers setup

I use a 15k in back with no bar....on real tires. Again, something in the 18/16k range is going to be pretty highly sprung on street tires, even with aero.

Hey merry Xmas to everyone btw. :)

Yeah if I was going full track beast with this car right now(not yet). I would probably go into the 15-16K front 10-13 K rear. I am aiming for starters at 13K front and probably just 9K rear until I can throw some aero on it. I only do road courses, if I did autoX I would probably go 14/10 to start. Biggest problem I have with the car is putting power down on exit. Like mentioned above, the rear end just likes to fly out on exit which would indicate *** end is rolling over and a general lack of stiffness.

Strange because that's what this car does best is put power down while hitting apex and exit..... What's ur alignment

Completely OEM. That's part of the problem. Trying to finance the whole shebang at once. But I may just end up needing to do the camber arms wo having the dampers yet.

This is a GREAT thread.. I have been looking a coilovers myself. I am currently running Swift R Spec and the OEM Nismo Shocks with Hotchkis sways.

All this good info is helping me lots on what I want to upgrade to. Keep it going.

Just do camber arms first, good alignment will make a huge difference, but ideally u would do coilovers at the same time so you can corner balance and align it (pay alignment only once)

Tires and a diff will make the single biggest impact on how the car handles and exits the corner.

The coilover is not worth it. Save your 2k and get camber arms and sway

Even with stock vlsd, still manage fast laps, yes the diff is huge. Tires for us not so much in SoCal we run rs3 mostly and a few on Td's we don't run Hoosiers like NorCal or other areas.

Here are my rear spring dimensions that was asked prior 8"x2.25"x 450lbs

You will max out stock suspension fairly easily, took me about 5-7 track days to max out the car easily on stock shocks/springs and front and rear camber arms only w rs3 tires. Next was coilovers, diff, sway bar and dropped a lot of time there.

Yeah that is kind of why I went the route of buying the Quaiffe diff first. Everything I read suggests that it is 1 of two things:
1. Not stiff enough springs
2. LSD.

I couldn't pass up the Xmas sale at Z1 lol. Got it for less than a grand. The OEM suspension all though not terrible by any means(for OEM it is quite good). Man it is way too bouncy. Scares the heck out of me at BRP from grapevine through club corner, and I feel I really limit myself at AAA and Big willow through the fastest parts, because once things start shaking, I back off. BRP the car hardly ever gets planted it seems with all the camber and elevation changes. Definitely need some faster springs as well.

Right now it's lack of track suspension alignment=no front or rear camber arms

my Tein monoflex are 783 front and rear. Both Mike Skeen and Brian Kleeman loved the way my car handles when they drove it.

That has to be a real coilover in the rear at that size?