BIGPOPPAPUMP

I just got Avant Gaurde 19X9.5 19X11 & it did wonders for my handling. I bought an Eiback pro kit to get "improved handling" and create a better stance. Well...... they car's handling got a lot worse! It's softer, more body roll. I even heard my new Hankook Ventus V12's squeal?! I think the spring rate is even lower than factory?! Or maybe the shocks aren't working with the spring? I'm stumped. I thought I did my homework. My car only has 14k miles. Do I swallow my pride & put the stock springs back on? Coil overs are a ton of money. I just blew 230 on the springs and 432 on the install. any thoughts fellow Z owners???

Emski

Did you get an alignment?

NoQuestionZ

iTrader: (93)

You got screwed on the install for sure! $660 is just a few hundred from some used Tien basics on the marketplace..... anyway, I just installed my boys eibachs (for a 1/4 what you paid) and he loves them.... I dont know 100% that it would matter, but did the shop put them in right side up? and did you have an alignment done? they could have put your springs on and left you waaaaaaay outta specs causing your V12s to do next to nothing if they are barely touching... just a couple thoughts that came to my mind.

beezee

iTrader: (19)

In the first place if they charged you that much to install just springs, they will sharge the same if you want to go back to stock springs because it is the same process. What I would do is, look at the DIYs here for spring install and use that to look over the whole install and see if they did things right. (Not saying re-install but once you get the understanding of the process, you can pin-point any screw up). Either way, get an allignment done first

ronn1

iTrader: (1)

If your tires are squealing, could mean you're working them MORE..that's a PLUS. Pro kit is definitely stiffer (rear rate is same as 04.5+ models)/lower than stock and should handle better as well. You DEFINITELY NEED TO GET AN ALIGNMENT! Make sure it's a reputable place. I wouldn't use the same guy though...$432 is WAY too high...$300 or so MAX labor.

INFO:

All rates are linear unless noted


350Z oem spring rates 2003-2004
314/342

2004.5 - 2008 (suspension revised midway into 2004 production, revision increased rear spring rate, revised shock damping front and rear, stiffer front sway bar and revised rear dustshield/bumpstops)
314/427

Eibach 350Z progressive springs 1”/1” (Pro Kit)
Spring rates in LBS initial/final front 296/384 initial/final rear 316/421

Eibach 350Z sportline progressive springs 1.2"/1.2"
F: 239/400 R: 257/435

mr. sparco

iTrader: (13)

Your shocks/struts are shot.

bmccann101

iTrader: (16)

body roll is not dealt with by your springs.. thats your sway bars job for the most part.. ( please dont anyone go into a physics argument.. im just saying that in this issue hes not looking at the next newly exposed weak link)

you upgraded springs and are now falling short in the sway bar arena, which makes one of the most noticeable differences in in suspension from a seat of the pants stand point.
Get a set of sway bars and you're set.. at 14k miles, your stock shocks have a good 40k left in thier life.

ALO8

iTrader: (5)

wtf!! that sucks.

mr. sparco

iTrader: (13)

I didn't read the post and missed the 14k miles. For the sake of arguing with you for fun I stand by my point, shocks are blown.

davidv

iTrader: (2)

Handling will be different of course. You determine if it is better or worse. Side-to-side porpoise ride increased or decreased. Small bumps now jar your teeth? Front end plow now increased or decreased?

bmccann101

iTrader: (16)

ha.
this is always a reccomended policy and is completely acceptable. haha.

my "dont argue comment" was aimed at an yet unknown assailant not yet in the thread that seems to ALWAYS pop up w some wiki quip argument about vehicle dynamics and physics... u know the type.

Waiz

iTrader: (57)

I'm going to have to say +1 on alignment or OP did something wrong during the install

dreamspeed

iTrader: (1)

432 dollars for the install? that seems like highway robbery to me, isn't a simple spring install like a 2 hour job? So even if they charge you a 100 bucks an hour (which seems quite high) that's only 200 bucks.

i installed some eibach pro kits on my Z about 6 months ago and i'm also running on hankook V12s, i felt there was a slight-moderate improvement in handling. And i know YMMV in this department but my handling didn't change between the before/after alignment.

BIGPOPPAPUMP

Well, thanks for all the info. You touched many aspects and the thoughts that ran through my head. I'm an F-16 mechanic & now build aerospace APU's Engine's. I've built cars & suspensions but was hurt in combat. I've ran Eibach's on my Cobra & H&R's. Both gripped a ton.

Problem is, the car previously was very stiff both laterally & linearly stock with just the wheels & stock susp. I had little to no body roll or much give at the springs. Someone gave the rates & the Pros were softer than OEM 296 vs 314. They are also progressive. I feel like I just didn't do my homework enough. Maybe should have done linear or coil over. Stock was so good that I thought a spring would just unlock a beast with little cost. I can rule out the shocks being blown cuz they were fantastic. Maybe the shocks are now under load since the car is low & the two can no longer work in concert?? I'm picking at straws here.

I'm real familiar with the dynamics of cars, especially my own. I have softer springs in my car..... or, something's up with the install..... or maybe they're upside down. lol IT HAS YET TO BE ALIGNED HOWEVER. I was told to let the springs settle. I don't see how an alignment is going to make a spring stiffer?? IDK, guys. I kinda have to laugh in order to keep my sanity. I am really thankful for all the advice & keep you posted. I did contact the COO of the shop but I was the one who chose the springs. He is recommending a sway bar & shocks but my car was a grippy beast prior. I could even drive enthusiastically on rough pavement. I guess I'll wait for the alignment next week. I've got roll and bounce now where before I had neither. Please chime in if something sticks out. I read posts of guys with similar scenarios but if people get their answer or fix, they often no longer have the need for the forum so the solution is never heard. I'll tell ya how this one ends. Thanks..

flecko28

iTrader: (13)

It's a long shot, but have you checked to make sure your sway bar endlinks were bolted back on? It probably isn't the case, but it's easy to check and cross off the list.

bmccann101

iTrader: (16)

Good idea for sure.

ronn1

iTrader: (1)

Bottom line..car should NOT handle worse than pre install. Period end of story. It's NOT the shocks or sway bars. First..GET THE CAR ALIGNED. Then report back. Have alignment guy ..read>>not the same guy that installed set up>>>>....check to see if shocks and springs were properly installed.

bmccann101

iTrader: (16)

ronns post is legit, it should be much nicer and more crisp, somethings wrong.

BIGPOPPAPUMP

Ok, I have my instructions. Monday, I'm all over this.

BIGPOPPAPUMP

All this has got me worried. So since I have such a loss in linear & lateral stiffness something is truly wrong? They did forget to give me my wheel key back. Makes me wonder about the sway bar links or the direction the springs are in. Also are their trouble areas for a spring swap that if they got frustrated could have fudged. I thought a heard a cutting tool going at one point. lol. It's a big shop & hopefully nothing on my car was cut. If I look under the car can I see the sway bar links & are the coils closer together at the top or bottom? Should the grey Eibach writing be right side up? My head is really going over time on this. You know how we are about our cars. I'm terribly meticulous but haven't the space in my garage & live where it rains every day....... Not to mention my tires are expensive. I'm hoping there is a fixable issue because I can't have my Z like this.