Topic: Eibach pro vs. stock GXP springs question

[SeLFMaDE]

I have an 07 GXP and I'm thinking about installing the Eibach pro kit springs, mostly to get the car lower. For how and where I drive I'm satisfied with how the car handles. I know the Eibachs would be a significant improvement over a stock NA setup. I am going to notice a major difference over the stock GXP springs as far as handling goes?

Also, I've read there are a few "unofficial" GMPP alignment specs that are different than standard. If I installed the springs myself and took the car to the dealer and instructed them to do the recommended autocross alignment would they know what I'm talking about?

Thanks.

[BLK GXP]

I have the pro kit and it rides good. I like the stance, and handling is at least as good as stock. Some dealers may align it however you want, but some may not. The dealer I went to said they could only align it to the specs they have listed for my vin. I know this is bs, but I said ok, because I didn't want them doing something they were not comfortable doing correctly. At least it is not out of whack anymore.

[Ben L]

There are plenty of performance places with laser alignment racks (at least around here) that will align to your specs. 

I think you will need to take the specs -- camber, caster and toe, front and rear, in degrees -- with you, rather than saying "align to autocross specs."

Setting rear caster on our cars requires a special tool (you can't very well turn the rear wheels across a 20 degree arc), which I'm not sure non-dealer performance shops will have.

We just set rear camber at negative 1.5 degrees and did not worry about rear caster, and the car turns and tracks great.

[lil goat]

I can not remember the exact wording on the GM tech bulletin for the Z0K alignment specs I believe it is titled Aggressive driving alignment or something like that. Here are the specs.

Camber Front -1.75 +/- .75 deg.
Rear -1.5 +/- .75 deg.

Caster Front 7.75 +/- .5 deg.
Rear -4.0 +/- .5 deg.

Toe Front .10 +/- .2 deg.
Rear .10 +/- .2 deg.

My car is in the shop now getting the B0K alignment, front camber is -2.3 instead of -1.75 thanks to Ben!

From reading a lot of posts people with GXP's are pretty happy with the Eibach's, people with NA's are very happy with them, different shocks. Just so you know Pedders also makes springs for the Solstice, they are a good company but I have never seen anyone who has installed them. They are HUGE with the GTO guys.

[Dan]

Just so you know Pedders also makes springs for the Solstice, they are a good company but I have never seen anyone who has installed them. They are HUGE with the GTO guys.

Thanks for that, had not heard of these.  I went back and found some info on the BB.  But not much!  Would be nice to hear some impressions on the Pedders.  Or in Utopia, somebody who tried those and Eibachs on their Kappa.

[lil goat]

I can tell you about 50 guys who run complete Pedders setups on there GTO's my son dreams of these, he told me they made some Solstice stuff, they have a great rep. If money was close to the same I would go Pedders just to be different but that's just me.

[Filipp]

Whats the lowering on the Pedders springs? If they did like a 0.5-.8 I might go with them because I don't want to lower it 1.3 which is what the Eibachs do but still want a small lowering.

[Dan]

They're about $360 a set, which is a fair amount more than the Eibach.  But they claim a lot tighter tolerances.  I guess we're not talking about much of a price difference where $200 billet cap buyers (I was one) are concerned. lol

Re: Filipp - I don't know the drop, but what I saw on the BB was "about an inch".  Would be interesting to know specifics.

[lil goat]

Kappasphere has the Eibachs for $199, the Pedders are 630 mm front and 635 rear, I have no idea how that relates to anything because I can not find the stock length or the Eibach length. I know Wretched Motorsports at one time was a supporting vendor on the BB they may have some info, they even wanted a test car at one point with a big discount.

[oldskool]

This may be slightly off topic, but how well do our stock Bilsteins hold up to lowering springs?  I come originally from the Jbody world, where the stock struts weren't worth spit.  If the car is lowered an inch, will the stock struts last?  Will they adequatelly dampen the higher spring rate?

IMO, the stock GXP set up is pure bliss.  My first functional suspension mod will be the DDM backbone, and possibly the pro beam after that.  Lowering was more of an asthetic mod to me...

[DeepBlueGXP]

This may be slightly off topic, but how well do our stock Bilsteins hold up to lowering springs?  I come originally from the Jbody world, where the stock struts weren't worth spit.  If the car is lowered an inch, will the stock struts last?  Will they adequatelly dampen the higher spring rate?

IMO, the stock GXP set up is pure bliss.  My first functional suspension mod will be the DDM backbone, and possibly the pro beam after that.  Lowering was more of an asthetic mod to me...

Cheers is the only one who had lowering springs that sheared a shock at the top of the piston.  With your HP, the two DDM products are a great upgrade

[Bosch]

This may be slightly off topic, but how well do our stock Bilsteins hold up to lowering springs?  I come originally from the Jbody world, where the stock struts weren't worth spit.  If the car is lowered an inch, will the stock struts last?  Will they adequatelly dampen the higher spring rate?

IMO, the stock GXP set up is pure bliss.  My first functional suspension mod will be the DDM backbone, and possibly the pro beam after that.  Lowering was more of an asthetic mod to me...

That would be question to answer is what the stock shocks are set up for.. Since I was just raised that you never changed springs without changing the shocks to match.. You don't want something that can't control the rebound. I have seen the dangerous habbits a car can pick up after just swapping springs. But the billsteins are adjustable aren't they? so you could tweak them to work with the new springs or am I off base?

Adjustables are new territory for me, sure they make them for the PT, but I run a lowered Eibach spring/Tokico shock/strut and left it at that. Sway bar upgrades did a lot more for the PT than adjustable shocks/struts would ever do for what I wanted.

[oldskool]

I don't think our OEM Billsteins are adjustable, at least haven't heard as much on the forums or advertised from the factory (would be a big selling point IMO). 

[Ben L]

They are definitely not adjustable.  I have four sitting in my garage. 

[DeepBlueGXP]

I have 4 sitting in mine also.

[Critterman]

don't you have 8 Joe, 4 GXP and 4 N/A?

[snaponbob]

Referring to the toe IN setting for the front that is part of the "race" alignment that GM issued. It is just WRONG. For Solo the camber is also too modest. One should look at at LEAST 2 degrees negative front and at LEAST 1.5 negative camber rear.

Getting back to toe in/out on the front - at factory settings (for Solo) ALL Kappas will "turn in" decently, but not well, and then will understeer. Toe IN will make this worse. Modest toe OUT will really help the response of the front end. Proof? Ask anybody that has tried both. More? At a Divisional this past weekend a fellow named Bob Lunz and his daughter  (from Iowa or Nebraska I believe) showed up with an 06 2.4 Sol in C/S and C/SL. the ONLY mod was 285/30x18 Hoosier A6s. After her first run (day one) I asked Bob and her what pressures and toe settings they were using. We agreed to first lower the pressures and that helped. Then they agreed to let me set their toe settings to what I used (1/8 out in front, 1/16 in rear). Talk about kids in a candy store !!!!!!!! Bob was really liking it. On Sunday he came in after his second run and was shaking !!!!!!! After his last run he said that the car had simply never done what it did, over this weekend, since he started racing the car three years ago. TOE OUT FRONT WORKS.

[lil goat]

I have asked and read a lot of posts about the Eibach's, it seems most are less than thrilled with them on the GXP, but they work quite well with the stock N/A shocks. I blew 3 of the stock Bilsteins with stock shocks, won't happen again they are sitting in Joe's garage with Critter's where old Solstice parts go to die.

[PURE_Fun]

I have had the eibach sportlines on my 2006 since about March 2006 and my shocks are still nice and clean they have never leaked.  I know in the beginning I read several posts about them leaking even with the stock springs, so go figure.

[LiquidPT]

They are definitely not adjustable.  I have four sitting in my garage. 

That's my fault. I had thought I had read somewhere they were and gave her bad info. Prob on one if the other cars I was looking at.

[Ben L]

No biggie.  You know you'll get the straight skinny here!

[Arabas]

i have the lowering K&N (i could say same as Eibach) on my Opel GT (same as Redline/GXP) with stock OEM Bilstein springs.
do you suggest i should get a different alignement than stock?
the car really handles better while cornering. and what i like most is that from APEX and on, the car seems to drift it s way out of the corner ( i am talking about tight turns - not on highway turns ).

Pls post if you know if i should get a different alignement and if so, what are the numbers i need.