Great, thanks for the mini-review and I look forward to your post.

Does your G have any 'rear-end sag'? Thanks again.

 

Does my rear end sag??
LOL. that's getting kinda personal (JK )
............
Can you clarify what you mean by sag?

 

Does your rear end sit lower than your front? I used Eibach springs on another car and it looked like the rear sagged; like the springs lost their springiness. thanks.

 

'05 350Z springs on an '04 AT Sedan

Couldn't find my old measurements...
Just took some new ones.
From the top of the fender arch to the ground
Front is 26.75"
Back is 26.625"

Also take into account I'm running 245/40 18 skins,
which will take .3" off the OEM running height

So compared to OEM - (if I was on OEM rubber)
Front 26.75 + 0.3 = 27.05"
Rear 26.625 + 0.3 = 26.925"

Ride height change
Front 27.99 (spec OEM AT) - 27.05 = 0.94" drop
Rear 27.72 (spec OEM) - 26.925 = 0.795" drop

So less drop at the back;
no saggy bottom

 

inTgr8r, would you rub the rear tires if you had a backseat full of people and a full trunk?

 

Do you guys recommend Tein 350z H or S Tech springs for a nice drop.

 

No rubbing issues with mine.

Rubbing is more related to wheel offsets.
If the wheel is moved out too much it can catch the fender lip.

Rear camber setting will also impact rubbing issues.
- (after a drop & camber is corrected)

 

I have a 6MT sedan, which comes with the sport suspension. So, by going with the stock ‘04 350Z spring, the ride should be the same or very close?
Do the Z springs drop a sedan 1” with compared to the sport suspension or non-sport?
Did your car have the sport suspension? I am curious to know where you started from for your ride comparisons.
Thanks.

 

There is a slight difference between 6MT & 5AT sedan.
Sport suspension is no difference.
Mine was a 5AT with sport suspension.

Here is OEM spec for the '03 - '04 sedan

 

The best way to determine differences in ride heights is to compare the spring rates between the springs and the length of the springs. For example one rear spring (504 ft-lbs/inch) is 305 mm in length and a stock G35 rear spring (342 ft-lbs/inch) is 325 mm in length. So it would be safe to assume that you would get a 20 mm drop in the different springs. However if the spring rate is greater than stock, (504 vs 342) you could expect less than a 20 mm drop. More spring rate = more resistance for spring compression. My guess would be that with a 504 vs 342, the original ride height would be maintained, even though the 504 ft-lb spring is 20 mm shorter.
Progressive springs could change that of course but that is the general idea of selecting springs and determining the amount of ride height difference by comparing spring rates and lengths to the springs you have now.

 

Does anyone have pics of the oem 350z springs on a coupe? I'm looking do use those springs as well....Also, are you using your oem shocks or did you replace them? TIA for all the input