For what's worth, I never had any luck with revalved Koni's on the Z. Had them rebuilt twice (8242's) and they always leaked with less than 100 track miles. The motons have been on the car for two years and not leaked a drop. Also, its been my experience that any twin tube koni (yellow), even with a custom valving for higher spring rates, sucks when you get over the 700lb mark. They are also nowhere near as compliant on bumps, etc as the high end monotubes.

 

Well 03threefiftyz, i would expect your Yellows to leak because you push your car to the limits at the track every time you drive it and probably overloaded them with your driving style, I wouldnt expect your motons to leak or bust or anything just for the simple fact that they were designed for that type of abuse and thats why you had to upgrade your dampers to them. He is using his car as a weekend warrior car at the most, seeing little track time, and mostly street driving. Blu, i would serioudly consider this setup because of the cost and the options to upgrade using the same components from your first setup

Koni Yellows OTS
Front Nismo OEM spring (rate=492lbs/in linear)
Rear OEM revised suspension spring (rate=427lbs/in linear)
Hotckis sway bars (Blu already has those)
Energy suspension master bushing set

OR

Koni Yellows OTS
Any matched linear custom springs (Eibach ERS/ESS, Hyperco, Swift, etc) (koni yellows have a threshold of 500lbs/in for spring rate) (good front to rear rate would be 500lbs/400lbs)
Hotckis sway bars (Blu already has those)
Energy suspension master bushing set


This will have his suspension in good working order and make the car feel like a completely different animal. This also gives him the option to move up to a high suspension if he feels the need to because of his base setup right now.

 

Thank you Stuart for your comprehensive post. I feel I am getting closer to which parts I need to get.

Springs are pretty-much the main component that dictates ride height, correct? I saw some posts about potentially making the car ride higher than normal. I don't want my car to ride any higher than it already is.

 

Your absolutely correct only if your shocks arent height adjustable, so using the Koni yellows your height can be adjusted thru the springs.

Beware though the only way you can do a custom spring for the front is by using a Tein tapered spring and using custom front spring seats to make it work, Koni sells these if im not mistaken, in a nonadjustable and adjustable form just in case you want to corner balance.

The rear springs you can use Eibach ESS springs make sure they are 5.5' outside diameter so they will fit, you can buy Stance adjustable spring seats or any rear spring seat for that matter, just make sure it fits those springs.

Now this is where the height comes into play on the spring.

When you buy your springs, They will list a length for the springs such as "9.5' x 5.5' OD" or soemthing like that, and thats what you will have to go off of to determine your spring height.

The stock rear unrevised OEM spring free length is 12 3/4"
The stock rear revised OEM spring free length is 12 7/16"

I couldnt find front spring lengths, but the OD for the springs is 4"

Now when you order your springs to determine your height you just get a spring of the proper length, ie you want a 1 inch drop you need a 11.5" free length on your spring.

Also, higher spring rates will cause your car to sit higher because the spring wont compress as much when the car settles onto them. So if you have two springs of the same free length, the spring with the higher rate will give you less of a drop, if you have spring perches (the "coilover" part on coilovers) you can adjust preload to adjust height, but with just springs and shocks, you need to either go with a shorter free length if you want a higher rate, or get threaded perches to adjust height.

Example: You have 500lbs/in springs on a 2000 pound car. this will make the springs compress 4 inches.

You have 1000lb/in springs on the car now, when it settles onto the springs they will only compress 2 inches.

 

You should also mention. That spring rate will change height. My car for example, just swapped from 700lb front springs to 736lb springs, I had to lower my spring perches

 

Thanks terra, i had a feeling i forgot something about the spring rates and the length. Ima add it into my post

 

Higher spring rates typically mean that you feel less body roll going into and out of turns correct? They add that feeling of being more 'level' and flat while maneuvering, right?

 

Not necessarily, you want a marriage of the sway bars and a good spring rate, thats why you have to tune the suspension , but yeah too high of a spring rate = no traction on the street and low spring rates = increased body roll, "mushy" or "boat" feeling when driving, thats why you have to find a good balance between the two.

Also remember the sway bar itself is also a spring attached to the inside of each wheel and connects them together and its spring rate is what acts to prevent the body roll by twisting to keep the wheels down and planted on the ground.

How the Springs actually affect the roll is when the car settles into the turn the springs spring rate acts to resist the car from tilting into the turn, or just like you said keeps the car more "level and flat" in the turn.

The last and final way to reduce body roll is adding a lower center of gravity, which you will acheive with your drop. When you combine these three factors together and have a perfect formula, than your car will handle likes its on rails.

here read this, it explains what i just said very well.

http://www.thecartech.com/subjects/a...SUSPENSION.htm

 

In addition to custom valving to match your spring selection, another advantage of a Ph. II setup is that the Yellows are shortened. I've been told this is not critical but recommended. BTW, I updated the pricing in my earlier post based on a phone inquiry this week.