Intro
Alright so quickly to introduce myself and a little background...
I'm studying mechanical engineering at UIC and I received an "intern" / job position at Strange Engineering about a year ago and have been learning more about automotive parts than I could have ever imagined. Strange Engineering manufactures everything from racing axles, rear ends, spools, rear suspension units, struts to front and rear disc brakes.
Anyways, with the help of other engineers, i'm in the process of making my own custom suspension for my 2006 Z. I'll use this thread to keep all my information on and of course to get advise and opinions of others. I don't claim to be at all an expert and this is mainly a learning experience for me to get more familiar with the 350z suspension while also gaining knowledge about Strange Engineering products. This is simply a project for myself and we don't at all plan to mass produce these.

ONTO TO THE BUILD!
First thing I did was take off the front and rear shocks to measure the total compressed and extended lengths.
I started with the rear and will be utilizing a "true coilover" design.
This is a copy of my first notes. I did not take into account that the bushing will be compressed when assembled so since I've gone back and slightly decreased the recorded lengths by about .25"
Also the dimensions are very rough and i will be posting a revised CAD image tomorrow.
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1324.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1324.jpg" border="0" alt="Photobucket"></a>

Next, I figured out my stroke length by taking the difference between the extended and compressed length. I got this to be roughly 6"
I would be able to use this by comparing to other Strange Engineering shocks with similar stroke lengths all while keeping in mind that I plan to lower my vehicle at least one inch in the rear. I also noticed our mounts for the civic are very similar to the 350z so i plan to use them instead of having to custom make additional pieces. This would mean that I would use a shock with a base cup of a honda/acura and a shock body of literally any domestic application ranging from Camaros to Mustangs.

Jumping a few steps ahead and after trying different stroke lengths the following photo shows how i will assemble the stock upper mount to the Strange Engineering shocks. The main issue i had is the compressed length actually increased even with a shorter stroke compared to stock because of the mounting. At the end i decided that im going to have to cut the stock bump stop to decrease my compressed length all while maintaining a reasonable amount of extended length. And as the pictures show there will be an additional Koni bump stop mounted below the spring perch.

so far the plan is a compressed length of 14.146" (before cutting the stock bump stop after it should be around 13.6") this is compared to the stock compressed length of 14.5"
Now my extended length drops from 20.5" to 17.112".
However, I don't think this should cause much of a problem because the suspension will rarely see full extension (then again chicago potholes...
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1319.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1319.jpg" border="0" alt="Photobucket"></a>

The end result will be a shock with an adjustable extension, compression and ride height.
Simliar to our Honda/Acura shocks
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1325.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1325.jpg" border="0" alt="Photobucket"></a>

sorry if some of the information is unclear its a bit late and i at least wanted to start the thread. will make changes tomorrow

5/15/11

Just finished the entire assembly made the BOM and it should be assembled sometime this week
ill take photos of them soon as possible..
anyways heres an clearer CAD print of the stock suspension and dimensions i used.
also shows how iam adapting the stock top mount to our shocks.

<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=350zTOPMOUNT.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/350zTOPMOUNT.jpg" border="0" alt="Photobucket"></a>

and the final assembly is below. i still wasnt entirely satisfied with my compressed length because its only decreased by about .5" from stock so i will probably modify the bump rubbers.
final compressed height is less than 14.146 and extension of 17.112
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=EntireLayout.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/EntireLayout.jpg" border="0" alt="Photobucket"></a>

 

Looks like an interesting project. I'm sure you will learn a lot through going through the process.

 

blank post for updated information later today..
and thanks! hopefully the information will be just as useful for others

 

alright now i could definitely use some opinions on sprint rate for the rear.
this will utilize a true coil over design so i know i will have to take that into account. i've skimmed through another thread discussing all the available suspension systems and sprint rates so i have a general idea of what i want but i could definitely use some help on this. im thinking roughly 280 or 300 lb/in

 

what front spring rate are you planning to run?

280 rear matches well with 700 fronts.

 

im not sure what spring rate im running up front. what i choose for my rear will help determine that.
basically i'm at the point where im looking for a decent ride comfort but slightly more concerned about performance.

i did find some useful information that will help thanks to Gsedan35 in another thread.

Front spring rate x .688 x .688 = front wheel rate
Rear spring rate = rear wheel rate (true coilovers)
Rear spring rate x .649 x .649 = rear wheel rate (OEM design)

 

A 12k 5k combo is a little rough on the street, but works great on the track with stick street tires, no aero work and some of the 100 treadwear R comps.

 

just a quick lil math and comparison
12k= 672 lb/in = 318 lb/in wheel rate up front
5k = 280 lb/in = 280 lb/in wheel rate in the rear

stock wheel rates are
314/427 for 04+ revised

im a little concerned about running 280 lb/in springs in the rear when OEM
is 427 lb/in after a "revision" i would think if anything i'd want to run stiffer than this instead of softer...or am i overlooking something here?
For example Ksports run a 318 (wheel rate) front and 403 (wheel rate) rear...

Also, finishing up my order this week for the rear so ill have pics up immediately!
Will probably end up test fitting as well

 

Fixed for you, that is what you are over looking.

Nismo T2 race springs are 690 pound front and rear, running the rear in the bucket. 12k 5k combo is actually really close to the T2 setup.

I run a 700 pound Eibach front and a 5k swift rear for now.

 

quick update...
had to backtrack a little and decided to change things up to run a 6 inch stroke shock instead so custom bottom brackets would be necessary to keep compressed length lowered by an inch. will update by the weekend again with revised drawings...

 

i got some very useful information that i had not seen before in the suspension threads. thanks goes out to jarrodh77
basically he sent me a photo of his suspension that shows a 2.5" spring is able to directly fit on factory front top mounts. This is great because it reduces my compressed length over an inch and im still able to keep my stock stroke.

<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=25inchspring.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/25inchspring.jpg" border="0" alt="Photobucket"></a>

 

finished the rear brackets a couple days ago.
our machinist did a fantastic job! and even sandblasted them
i also ordered a 12" 280 lbs/in hypercoil spring for the rear
and should have the front and rear shocks assembled early next week.
front shocks were much easier than the rear since the top mount can accommodate a 2.5 I.D. spring. hoping for a full install next weekend.

<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1355.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1355.jpg" border="0" alt="Photobucket"></a>

 

Alright so a major update!
Got all my parts machined this week and install has started.
I hope to finish by Sunday but well see what kind of problems come up along the way....

The PARTS!
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1356.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1356.jpg" border="0" alt="Photobucket"></a>

Initial Rear Mock Up
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1380.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1380.jpg" border="0" alt="Photobucket"></a>

<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1375.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1375.jpg" border="0" alt="Photobucket"></a>

Problem 1:
The extension adjustment **** was positioned so low on the shock that the tabs actually hit my bottom mount so i had to slightly modify the plastic ***** (small chamfer on the back not noticable) and i grinded the bottom mounts a bit.
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1379.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1379.jpg" border="0" alt="Photobucket"></a>

Mockup
The Hypercoil 2.5" springs are very close to the body of the car ... id say about half an inch... i thought stance ran 2.5" in rear but maybe its 2" ...? anyways the 2.5 inch just barely works. and they are 12" long at 275
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1365.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1365.jpg" border="0" alt="Photobucket"></a>

<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1381.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1381.jpg" border="0" alt="Photobucket"></a>

<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1376.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1376.jpg" border="0" alt="Photobucket"></a>

In the end i think the rear went pretty well.
my extended length is 20" roughly
and i have about 1" thread on the shock body for raising my car and 3.5" for lowering it.

on a side note, need some battle version toe arms soon hopefully...

a very quick and rough mockup of the front
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1360.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1360.jpg" border="0" alt="Photobucket"></a>
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1357.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1357.jpg" border="0" alt="Photobucket"></a>

 

Looks like its coming along well. What is the spring rate you picked for the front.

 

i went with the 500 for the front.
based it on the nismo rates so i can still have a decent comfort level.
but given the compression adjustments i should be able to get my wheel rate up much higher similar to the setup u mentioned earlier.

 

ok so saturdays down and i got my entire passenger side complete
the biggest issue im having are the sway bar links on both driver and passenger side. they are the biggest pain in the *** to deal with and had to cut and grind at the nuts be4 replacing... to be continued in the morning

 

Great project, definitely looking forward to finished product!
I wish I was smart...

 

Great thread! I would be very interested in a set of these, my Stance coilovers suck ***!!

 

shock dyno at the end, right?

 

well .... uh bout the finished product... um... how do i say...
well lets let the pictures speak for themselves

<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1397.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1397.jpg" border="0" alt="Photobucket"></a>

idk why this pic but hey why not right!?
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1396.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1396.jpg" border="0" alt="Photobucket"></a>

first view of the front...can be slammed safely at times
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1394.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1394.jpg" border="0" alt="Photobucket"></a>

<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1385.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1385.jpg" border="0" alt="Photobucket"></a>

<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1383.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1383.jpg" border="0" alt="Photobucket"></a>


so this project took me three days to finally install and there are some minor flaws i still gotta work out... the rear right (first shock i did) is the only side i hear clunking noises in and im almost positive i know what it is but i have to disassemble it all 2morrow. clunky but it still functions damn well...

the biggest issue was again the sway bar links
<a href="http://s26.photobucket.com/albums/c125/NedimV/?action=view&amp;current=SAM_1389.jpg" target="_blank"><img src="http://i26.photobucket.com/albums/c125/NedimV/SAM_1389.jpg" border="0" alt="Photobucket"></a>

First Drive...
shocks were all set at complete soft compression and extension
backing out i noticed how much the body plunged forward because compression was so soft...
took it for a spin with all soft adjustments and it handled like **** and felt so damn wobbly every time i tapped the gas lightly i felt the front begin to lift. toook it back to the garage adjusted the compression to position 3 out of 10 and set the extension to 5 out of 10 ...
really i didn't have any specific method to fine tuning as of now i just wanted it to be stiffer. to adjust all i had to do was turn the front wheels completely to one side and stick my arm turn the ****.. done. in the back the ***** are exposed right behind the rotor and really easy to get at.

Second Drive with position 3/10 compression and 5/10 extension...
Finally some improvement it drove great and comparable to stock as far as weight transfer of the vehicle on extension and compression...
the higher spring rate is noticeable in turns and bumps... but its decent for daily driving.

overall, im more than satisfied. these are quitter (minus the right rear corner i gotta fix) than my previous koni and ground control setup i had on my old car...using the oem mounts and rubber "sleeves" around the springs saved me many annoying noises...im curious if any of the stance or other aftermarkets are noisy because i dont recall seeing any kind of insulators or anything on their mounts....

anyways, the handling is definitely improved and now i just need some adjustable toe arms

oh and for the heck of it the time to build the entire suspension, make all the cad prints, decide what shock body to run, machine all of the parts (mainly the four bottom mounts and an insert on the front top mount, have the internals assembled by our team, and get new sway bar link! took about an entire month...

oh and a shock dyno could be easily provided using a shock off the shelf thats the same as mine but obviously different mounting and so on... ill look into it im sure we probably have one at work already...