Yeah, Ground-Controls suck... IF you use the stock shock! many amateur race teams use Ground Controls with Koni or better shocks... why? Easy adjustment. And not just ride-height. If you call Ground Control and order from them you can specify the spring-rate you want. Don't like the rate you picked??... get new springs for 50 a pop. Try that with JIC or Tein.

Oh yeah, Ground Control uses Eibach springs... I guess all Eibach's sag.

Having said that... Getting a packaged deal (JIC, Tein, etc.) is probably better for the average (street) driver. But it'll usually be much more expensive.

Blake

EDIT: Found this on Ground-Controls website:

"Springs: All our ride height adjustable kits feature Eibach Springs. these high quality springs offer a lifetime warranty against any defects."

I would assume sagging would be a defect...

 

So I haven't seen one mention of the actual change in spring rate from stock to the eibachs...why in the world would you consider buying springs (or any setup for that matter) if you don't know how these springs will affect handling? Is it just so the car sits lower? Doesn't it matter if you bounce down the highway on the springs without compressing the shocks?
cabalisticfire, thank you for the sane reply.

 

In my experience with Eibachs they all sag. For the Grand Prix they had to release a revised set because the fronts were a full 1.5" higher then the back. Even with the revised springs the drop is still uneven.

 

Interesting. My only complaint with Eibachs is that they DONT always drop as MUCH as they say they do. This would be the opposite of a sag issue.

Intrax on the other hand keeps dropping and dropping and dropping.....

 

All springs will sag/fatigue to some amount. Some more than others. This is why it is important we can set the camber on our cars. Sagging springs will cause the insides of the tires to wear.

 

If you have adjustable-height suspension, just raise it up a bit to compensate for the sagging springs. Generally, a spring will only sag a certain amount during an initial break-in period. After that, it's probably safe to adjust the height (if you have that ability) and be done with it.

If you don't have threaded coilovers, some shocks (such as Bilsteins) have slotted mounts for the spring perches, allowing you to make limited adjustments to height. Not as fine-tunable as threaded coilovers, but still useable if your springs sag too much.

 

True... I suppose I meant excessive sagging would (should?) be a defect.

Blake

 

Response regarding one of the above posts about putting additional weight in the trunk in order to get a "feel" of what to expect with Eibach springs. I'm the first to admit I don't have experience in this area, but the physics seem backwards on the example. If I put more weight in my car now and the ride smooths out....how in the hell does that translate into the same type of ride with the same shocks and stiffer springs??? When I went to stiffer springs in a Wrangler I had...and kept the shocks the same, I had to put the weight in after the change to get the same kind of ride as before. This is consistant with logic for me: stiffer springs with more weight = softer springs with lighter weight.

 

The logic was that if you compressed the stock springs with more weight in the rear, then they acted like higher rate springs with less compression. When more weight was put in the rear of my car w/ stock springs/shocks, the car rode better. Therefore if my logic is correct (it could be wrong) I think that stiffer/shorter springs would make the ride better or at least reduce the amount of porpoising @ certain speeds.

 

It says yours are on ORDER? PLease PM me about that.

 

I kind of understand what you are saying...but don't agree with the analogy. I don't experience any "porpoising" in my current stock ride...it is however very "bumpy" like I would expect from a stiff performance suspension. When you use the word porpoising I think of how any car would ride when it's shocks are shot ie. you push down hard on the bumper and let go and the car bounces numerous times to come back to static condition. If this is what you are experiencing, then I agree...shorter/stiffer springs will reduce this characteristic...but will not ride at all like your stock suspension under load. IMO that simulation is similar to making a Corvette into a Cadillac. The heavier weight in my eyes would promoat the "floating" feeling over bumps.....anyway, that's my take. Doesn't much matter...buy em and tell us your opinion afterward.

 

Oh ok... i see what you're saying, makes sense if it was a lot of weight, but I merely put about 40-50 lbs of stuff in the trunk I believe. So it's NOT like I added 2-3 hundred lbs of stuff to make the car heavier and basically ride over the bumps... Also, porpoising if you search is a condition in the Z where the car's rear will bounce up and down over certain roads excessively at speeds between 45-75mph... This was determined by several people who analyzed the suspension (and they could be wrong) to be caused by the shocks being valved too heavily for the stock spring rates.

 

Everyone is going to blast me on this....I can hear it now. But.....you mean there is a solution to my not being able to drink coffee in my Z on the way to work? (banter in the background, "you shouldn't have bought a Z if you wanted to drink coffee....it's a sports car!")

Honestly if what you are talking about may provide a better street ride without losing and maybe improving track performance....sign me up!

 

FYI

H&R have brought out a set of springs for the 350z. If you want something that sits lower that the Eibachs then the H&R's might be for you.

Eibachs
Front 0.8"
Rear 1.2"

H&R
Front 1.5"
Rear 1.5"

http://www.hrsprings.com

 

Someone buy them, install them, and report back to us....please.

 

Man that would look nice with some 19s tucked up there.

 

You guys might want to wait for the H&R springs. Supposedly it should lower the car by 1.5" all the way around. At least that's what my dealer price sheet lists. But, they're not out yet.

 

H&R springs are not out yet, the prototypes will be arriving in the first week of Jan. and I will be testing them on my car for them. Today (20 Dec.) we are doing the first of the testing on a stock car at 2pm PST at H&R to verify original #'s on the stock suspension.
I will post pictures and info this evening after I get home.
H&R is in my home town of Bellingham, WA. Nice to have people like that in my home town.

 

Dont go out and measure/test it the second you drop it. It takes sometimes up to 3 days for a car to fully lower. I bet you 20bux it doesnt drop more then 1/2" when you first do it. Then tomorrow you will walk out and look at it and say "wtf!"

Also, what are you doing about your camber?!