Anyone out there mix and match their springs? I have the OEM Z strut/spring setup right now. Need to lower the rear. I have a set of Z Tein S-Techs. Thinking of putting the rears on to even out the drop (need about an inch drop). The fronts are good so I want to keep the OEM Z setup there.

I know the spring rates are a little softer on the Teins vs. the revised Z springs in the rear. How would this affect the performance if at all? Any known problems with this?

Thanks in advance.

 

All that counts [other than body position] is the real tire road interface spring rates..............so called wheel rates.
Remember springs are in series with isolation mounts, wheel and tire stiffness.

 

bump, you got pics? I'm thinking of doing the same

 

Revised OEM 350z rear springs 427 lbs
Tein S-tech 350z rear springs 402 lbs

But, with S-tech’s reduced rear height and therefore weight transferred to the rear, while all other things being equal (shocks, sways, wheels, tires, alignment) I don’t think it would make much difference if any. Dive and squat during braking and accelerating shouldn’t be considerable affected neither.

If you don’t mind occasional bottom scraping, go for it.

 

It will be much stiffer than stock just because the actual spring has less travel (because it is shorter) and I think S-tech rear springs are linear. As far as handling goes, it is all preference.

 

Thanks for input guys.

I don't know why the Z setup didn't lower my rears at all. It seems like it is higher than stock. I'm down to two options other than going back to stock...

-spring mount mod (can controll how much it lowers).

-install Z s-techs (with the ride height the way it is with the Z setup, I'm assuming it will drop the car another ~0.7 inches as it would in the Z and not like if I was straight installing it on the OEM G setup.

G35brother:
I'll post pics when I can to show the fronts and rears (might take a while) w/ the OEM Z setup.

 

Because the springs are centered inboard of hub and center of wheel, the real stiffness at the wheel/tire is divided by ~~ 2.5. Ratio of proportion on the mount arm: o......XX......{}

The high rate of unmounted springs fools many into thinking the mounted rate is that number. But a % increase or decrease is a % at the wheels.

 

Shorter spring will bottom out sooner, but I don’t see how is stiffness affected until it bottoms out. Please explain. Thanks

 

Q45tech, I remember your wheel rate discussion with Jim couple years ago, when you guys concluded that:
427*0.53= 226.31*0.36= 81.4716
402*0.53= 213.06*0.36= 76.7016

Now where did this ~2.5 come from and which one to use? Thanks
427/2.5=170.8
402/2.5=160.8

 

s-tech rear springs are linear. So if u go over a small bump or a big pothole u almost are going to feel the same type of vibration inside the car. I read somewhere that linear springs have their full stiffness at all times compare the progressive springs that their stiffness depends on how much the actual spring compresses.

 

Correctomundo.

 

But both OEM G and Z springs are linear, and so are s-tech rear springs.
OP question was about OEM vs rear Z Tein S-Techs, not vs some progressive springs.

 

By any calculation, your looking at a 5-6% difference in spring rate. The two formulas above yield the same 6% change while pure spring rate difference goes down to 5%. Which I am assuming won't be too much difference in feel.

Am I correct in assuming that the softer rear will create more understeer in the car? But a 6% difference won't change that too much would it?

I like the way the car runs with the OEM Z setup and Hotchkis Sways. I don't want to change it too much, just that the rear looks like it's lifted due to the gap between the fender and my wheels.

 

yes i wouldnt worry about a 5%-6% change. a lot of my customers go with the 350z s techs on their 05's and like them a lot.

you will get somemore understeer but i doubt you would even notice it. if you do you can just adjust your sway bars to compensate for it.

 

WYSIWYG, hopefully someone more knowledgeable and with more suspension tuning experience will post here.

Lowering the rear of the car, because of weight shift, will be also decreasing oversteer or increasing understeer. But I am guessing not much. Some of it can be corrected with front/rear tire pressures and you can always remove the s-tech’s and cut the bump-stops if unhappy. I mean, it doesn’t take much to swap the rear springs and try it since you already have them.

In my case I was trying to dial out understeer, not the look, and it didn’t matter much what I did until after I mount 265/275 F/R tires.

Attached are some of the notes collected on this and other sites that I was using, perhaps they can help.