So as most of you all are aware, the springs from the 350Z's are supposed to lower the G35 coupe by 0.5" all the way around. If not 0.5" then maybe a max deviation of +/- 0.1"

Anyway, I bought a used set of 2008 350Z springs off a guy who had put Eibach's on his Z. I'm not sure if it was Enthusiast or Touring (I didn't see if he had leather), but his car was heavily modified, so one would assume that a guy with $5k to put into his car, probably paid the extra $2k for the touring package. Nevertheless, I don't think that makes a difference on the Z's spring compression rate.

I dis-installed my left rear stock G35 spring and installed this 350Z spring in its place. I dropped the car off of the jack, and the car sat literally about 0.25" HIGHER than when the stock G35 spring was on it. We took off the wheel and inspected everything, and it looked like we had done nothing wrong. The spring looked perfectly installed.

Granted, we didn't use any fancy tools to install the 350Z spring, but it was beyond perplexing why the car would end up higher than the way it started. Since time was an issue, we decided to take the Z spring off and reinstall the G35 spring. Lo and behold the car went back to the way it was before (lower than the Z spring). Completely inexplainable.

My plan from here is to sell these springs as they were sold to me. 2008 350Z stock springs used for around 35k miles. Then I would like to venture into getting a set of Tein or Eibach's for my G.

If anyone could explain why this might happen, please let her rip. I could have just installed it improperly, but I don't think that is the case.

 

Give the car time to settle.

 

If it needed time to settle after install, then why did the G35 spring go right back down to where it was before?

It would be just as if I had taken a G35 spring from a different G, and put it on mine...it really doesn't make sense!

 

The rear will be the same height, the fronts will sit a bit lower.

 

When the car is off the ground, the shock will decompress to its maximum length. Once you put it back on the ground, the fluid will slowly move through the valve and allow the car to settle. I've watch it happen on my car dozens of times. Take some ground to fender measurements before and after. The numbers won't lie. It's often times hard to notice such a small drop. .

 

If this is true, then why do most posts say that all four will sit 0.5" less? I would love for it to be true!


Okay. But again, if this is true, then why did the G spring immediately drop back to its original height? By your argument, the shock would need time settle, whether it's settling for the stock G spring or a stock Z spring...yet, the G spring immediately went down to its original height. If what you said is true, and the Z spring needed time to settle, then my G spring would have also, after time settled, dropped another 1/2 inch!

And yeah i know the change is slight, but my wheel gap is only about .8"-.9", so I figured a 0.5" drop would be great! However, it is noticeable that the wheel gap was larger when comparing the post Z spring install to the post G spring "re"-install.

 

Because the G spring is marginally longer than the Z spring, it would naturally have less distance to drop. It takes probably 2 minutes for a vehicle like ours with moderately stiff dampening to fully settle. That being said, the distance the shock has to settle on the Z springs is greater than it is with the G springs and will take longer. Initially when you drop a vehicle back on the ground, the weight of the car is going to force the majority of the fluid through the valve to get the height at say, 90% of where it is going to sit. If that extra say 10% in height is made up for in terms of the G spring, it will not have to compress any farther than what occurred when you put the car back on the ground. Get it?

Many people have measured/recorded the said drop on Z springs. The only difference between their situation and yours, is your individual interpretation of it. I think it's safe to say next time you should measure before/after to rule out any over thought on your part. At least then you will have factual data and not just a hunch to go off of.

Edit: I just thought about this. Did you check to make sure you lined up your A point correctly?

 

z springs are a waste of time drop...barely even noticeable unless your shocks are blown lol

 

Exactly what I was thinking the whole time I was typing my reply. I didn't want to be rude though.

 

Personally I'd recommend doing a complete installation, taking it for a cruise around the block, and then see where your car sits. There are various reasons why the desired effect may not have been met. I would not jump to conclusions if you only did one corner, and the car never left the garage.

Not that I'd want you to waste time doing this, but there are countless instances where people have recorded a very mild drop.

 

For unrevised yes, revised Spring which is what you have is the same height in the rear as a coupe springs.

 

wellp, I wanted an excruciatingly mild drop, without having to worry about camber or shock wear. so the Z springs are what I wanted.


Well! So kind of you to be nice during your post and then rude now. how thoughtful. but see my above reply, and i think you'll understand what I was going for.


okay. I'll do that next time..


ah...wellp, good thing 75% of the information on the internet led me astray. Thanks for the correction.

 

I understand what you are saying, but I can't help to think that your physics are slightly flawed. Let me counter:

First, yes, we lined up everything perfectly, twice, and had the same result.

Secondly, it was not a "hunch" that we ended up with. We measured before and after, and that's how I got the measurement of 0.25"higher than what it started at. That wasn't a hunch, that was with a ruler measured from the edge of the rim up to the fender.

Third, for the longer point you made... I will examine this one phrase you made:
"That being said, the distance the shock has to settle on the Z springs is greater than it is with the G springs and will take longer."
Okay, that makes sense! I understand that sentence completely! However, your continued argument based on this phrase is what is physically askewed... just because the distance the shock must settle is further on the Z (which I agree with), makes literally no point as to why the car sat 0.25" HIGHER than the G spring for the INITIAL 2 minutes the car was let off the jack. I agree, it will have longer to settle, however, the starting point should be the same, should it not? Therefore, the initial height between the two should be the same, according to this longer-time-needed-to-settle theory (which still could be true), however, it does not explain the 0.25" higher result. Get it? lol I just wanted to say that back, but i hope I do make sense.


Edit (just an added post): don't get me wrong, I understand where all of you guys are coming from.

First, just because the shock takes longer to settle still wouldn't explain why the Z spring INITIALLY sat higher than the G spring, unlessssss (see my next sentence below).

Second, if the revised Z springs really don't lower the coupe in the rear at all, then maybe that would explain why the car sat 0.25" higher initially. This could be explained because my stock springs have 105k miles on them, and the Z's had only 35k miles...so the spring had more life, and since I didn't give the shock more than 10 minutes to settle, the car was never able to fully settle on the "firmer" (because it's newer) Z spring!

 

Just sell the springs u got and get the pro kit.. I have them on my car and it dropped it about 1.5 in the front and 1.2 in the rear.. The springs u bought don't really need to settle, cuz they already have 30K plus miles on them.. they are broken in already. Just my 3 cent

 

That's all I actually read, because youre arguing over springs that aren't designed to drop your car. I think its a fair observation to say the only answer that is Allowed to be right, is your own. That is, unless its black and white obvious as say, 2+2=4.