I also posted on the G35Driver board to see what their opinions are as well.

Ok guys so here goes - i know this thread is useless without pics, so i will get those up this weekend. In the meantime here are the results for some discussion:

2009 G37X with G37S coupe springs

The original height was about 4.5 - 5 fingers in the front and 4 fingers in the back (supergap) - with the springs installed it is now about 3.5 fingers in the front and 1.5 fingers in the back (so i got some of that droopy bum) I ordered some spring isolators to try and fix the rear a bit while i look for another solution for the springs that works perfect without any "fixes"

Took the car in for alignment - front is obviously within spec, the rear is sitting at -2.1 camber and thats as far as they can go...

When comparing the springs at the shop, both front and rear were exactly 1" lower than their X spring counterparts so it looks like the springrate in the rear springs is obviously not strong enough to keep up the rear (as the drop would have been even if they did)

I dont want to go with eibach's as i think they drop it too low for Chicago roads and I dont want to buy the front camber kit (im fine with purchasing just the rear tho) and i dont want to be at big negative camber.

Strangely it seems that even though the X's are supposedly heavier in the front, it negatively affects the rear (see Tanabe springs droopy bum on the X)

So thats about it.
And here are the pics!





Even though the drop is not that low in the back (compared to some other cars on here) you can see that the drop is uneven.

Front height:


Rear Height:


Here is the difference in the springs. These are the rear springs, the front ones were the exact same difference.
The right one is for the X and the left is the G37S coupe:





-IgS

 

I think BB put it perfectly, "fingers" is a measurement tool used to describe how far you got with your girlfriend.

Are you satisfied with the drop in the front? Im assuming you are since you are looking into isolators for the rear.

So in terms of fender gap, do you have about an inch and a half difference in height from front to back? (Im looking at my hands and measuring 3.5 fingers vs. 1.5 fingers)

I'd give it some time and see how much it settles. If the front settles a little and you can get a half inch to an inch in the back with the isolators, it might be an even drop.

Kudos for trying it out. About a finger and a half fender gap is what I have on my coupe with Eibach rear springs.

Or, you could always go back to the X stock springs in the rear and have a 3.5 finger gap in the front and a 4 finger gap in the rear. That way it would have a slightly aggressive rake to the front and the gaps would be pretty close..... plus, with an alignment, your rear would be back in spec and no camber kits.

I guess it depends on how much of a drop do you want on your car?

 

Haha agreed,

just wanted to give a rough idea of what it was, unfortunately i didnt measure or take pics right after the install - ill do that tomorrow and update this post.

Im not 100% happy with the front as I would like it a bit lower. Im getting the isolators so that i can bring up the back a bit so it doesnt look awkward and also i dont wear my rear tires with that negative camber.

Technically, if the front is brought down lower and i get the camber kit for the back, it would be great, but i really dont want to mix/match springs

In a perfect world I would have a 2 "finger gap" all around

I was also looking on H&R's site (http://hrsprings.com/scripts/appguide.php?Mode=Make+Guide&SubMode=Find3&MakeID= 15 ) and they came out with some new parts: G37 Sedan and G37x Coupe.

I know the H&R springs everyone was using before said they were for the gen2 sedans while they were the same parts as the 1st gen and dropped the car waaay too low - so looks like this might be addressed in the new springs. And the G37x coupe srpings give a more conservative drop than the Eibach Xcoupe springs.

My thought on this is technically the coupe springs should work on the sedan as long as the spring rates are fine. Since the X coupe is just a tiny bit heavier than the sedan (40lbs) im thinking maybe these would work???

thoughts?

 

What was the weight difference of the Xsedan and the coupe? Im trying to think why the S coupe springs were that uneven for you first.

Also, say the weight difference is only 100 lbs, it might depend on where that weight is. Say one car is a 50/50 distribution, and the other is a 55/45, even though there is only a 100 lb weight change between the cars, one car might have much more weight on the rear vs. the other car.

I would look into that for the coupe and sedan differences. The springs are going to fit, the question is if the springrates will be strong enough to support the rear and the front of the car the same and how the car will sit.

 

Its roughly 150lbs.
I think there is more to it than just weight, i mean 150lbs is basically me getting into the car, so it should not make that much of a difference - but the X definately responds to springs differently than the regular sedan with one person in it... at least based on the research here...weird

 

Yea, 150 lbs is definately not enough to cause a 1 inch or greater change in height. Thats maybe a 1/4 inch height difference on stock springs. Definately not the change you saw.

Unfortunately, I dont have an Xsedan or know enough about the differences in suspension to speculate what else could cause the change.

I would guess though that the Xcoupe and Xsedan suspensions are similar though, so the Xcoupe springs might be a better match for the Xsedan, and the weight differences should be close.

The front of the cars (suspension and weight) should be identical so whatever the drop of the Xcoupe gets, the sedan should be the same.

 

Im really considering the H&R's Xcoupe springs - but im a little weary about trusting their numbers. They list the same drop for the regular coupe and the Xcoupe - even though the Xcoupe sits higher stock... ugh

 

Can you check the individual part numbers for the springs? If they are different springs, its possible that they end up with the same drops.

If they are the same exact spring, then I would be skeptical that they wouldnt produce the same drop....... just like the Scoupe sport springs you tried out.

 

Model:-------------------------------(Front/Rear)------Part#
G37 Coupe 3.7L, V6 2008-up-----------(1.5 / 1.4)------#53030
G37 x Coupe 3.7L, V6 AWD 2008-up----(1.5 / 1.4)------#53034
G37 Sedan 3.7L, V6 2009-up-----------(1.3 / 1.2)------#53031

I called H&R - the G37 Sedan and G37X coupe are still in R&D so they couldnt really give any answers. I know that if you use the Sedan springs on the X, add another .5 to those. If the Xcoupe #'s incorporate the .5 inch difference on the X's i might pick those up once they are out. If they dont - well then my car will be laying on the floor.

 

any pictures yet?

 

Updated with pics.

As far as the ride quality: I can say that I feel the back feels a bit too soft, just feels that the back is a bit more "loose" Its in no way bad, maybe i just expected more and its in my head as i keep thinking that these springs were not made for this... I had friends ride in my car and they said it feels the same, so it might be a placebo effect.

This might open up some experiments for mixing springs - but i feel that all 4 springs should be from the same model as they are "designed" to perform together - but i might be wrong on this as i dont have too much knowledge in suspension, just speaking from experience.

 

Theres nothing wrong with mismatching springs, as long as you pick correct springs that would work with each other.

But, you wouldnt want to put 9k springs on the front and leave the rear stock. Even if it was a dead even height, the huge difference in springrate would make the car feel very funny. You wouldnt want a very firm car in the front and a soft car in the rear. As long as you keep the springrates comparable, mixing and matching is the same thing as running custom springs.

People who track often put custom springs on their coilovers to change the springrates from the stock coilover springs. Its all personal preference. Check out the tanabe website, they list numerous springs with springrate combinations for their sustec pro coils.

A good rule of thumb is that you usually see no more than a 2kg difference in springrate from front to rear. Some people like a stiffer rear, others like a stiffer front.

 

What about running G37S SEDAN springs on there? Do you think you'd get an even drop that way? Or running the H&R's with the spring isolators (not sure what those are) to lower it less?? I'm looking to do something similar. I want to drop about .5" to 1" (max), but nothing seems to do that.

 

I'm going to try Coupe 37S front springs and just shave the upper spring seat on the rear(keeping stockX rear spring) of a '10 37x SEDAN...and see if that's the magic combo that we've all been waiting for...Pics to follow...it will be a ThanxGiv project. Wish me luck.