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Discussion Starter #1
I have the Eibach pro kit springs, but a friend of mine offered to trade me for his Intrax springs. Which are better performing springs? And are they ok to use on my stock struts?

The specs according to the "Official Suspension Thread" are as follows:

Eibach Pro Kit

F: 137 lb/in
R: 171 lb/in

1.5"


Intrax

F: 225~275 lb/in
R: 275~325 lb/in

1.5"



Just not sure which would be better according to the spring rates, since I'm not sure what spring rates mean (if someone could fill me in on that I would appreciate it).
 

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The Intrax springs would be the better performance springs, but those rates are fairly high. You should expect a stiff ride, but if you keep stock dampers, you won't notice it as much.

Ataru told me when he put Intrax springs on his friends SVT, his friend kept the stock dampers in. When Ataru rode in the car, he said his KYB dampers and Apex springs rode stiffer than the Intrax springs did. Once you upgrade the dampers, you will finally notice the difference.

I also think the Intrax drop is a beautiful balance of fender gap and ride height. That's just me. You could easily buy some aftermarket dampers that would suit the springs and give you excellent control and adjustment for sporty/competition driving.

Both kits will wear out your dampers, but with the higher spring rates of the Intrax, I would assume that will overwork the dampers more than the Eibach springs would resulting in a worn out to blown strut/shock sooner than later.
 

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Discussion Starter #4
I'm searching for some moderately priced dampers right now, but I do wanna put the springs on. I am looking more for performance than comfort, so I suppose I'll be going with the Intrax. Thanks for the feedback guys.
 

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Discussion Starter #6
A friend of mine is willing to trade me his intrax for my eibach. Thanks for those pictures, they help cause I actually really wanted to get the back lower, since that's the gap that bugs me. You wouldnt happen to have a full side picture of that car would you?
 

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fyi, the spring rate is the stiffness of the spring. It's the amount of force (137 lbs for instance) required to move or compress the spring one inch. F=k*x where k is the spring constant (spring rate). From the numbers given above, the Eibachs require much less force to compress and so will be squishier, aka softer ride. However, they have progressive rates which means that as the spring is compressed tighter, the rate increases, to firm up the spring and help you from bottoming out. The Intrax might have a constant rate, so whether your spring is compressed 1 inch or 8, the ride will feel the same. Your friend might think that his ride is too harsh for a normal basis which is why he wants to trade [:p]
 

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Hmm, I never even looked to see that the Eibach Pro springs were progressive. Quite interesting.

That spring force equation only describes the motion of a simple linear spring. We, however, do not know the exact behavior (could be k^2, k^3/2, etc.) of the Eibach Pro springs, which although progressive probably never reach the high spring rate of the Intrax.

I agree. I bet your friend hates the harsh ride if they've been installed. Is he still on the OE dampers?

I know there are a lot of Eibach Pro kit owners that can chime in here with their experience. The Intrax people might be far and few in between.
 

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Yes, Eddie is still on his stock dampers, but if you look at this pic:



You can see the rake too.

That is the reason I didn't put them on my car. But I might reconsider to get some stiffer springs for auto-x. I don't know. I'm torn.
 

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I know, and I saw it too. While I think the front could be a little higher, I love the fender gap in the rear on the Intrax. I still think it gives the car a nice stance despite the rake (it doesn't seem as accentuated in my eyes).
 

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Discussion Starter #13
Actually, I dont think the rake looks too bad. And by buddy (HTPerformance on here) actually has never put them on his car. He just decided he didnt want his car too low. Well, I'm gonna get them. They'll be installed and pictures will be taken the weekend after I get back from Virginia. I'll be riding on stock dampers for a month or so, then I think I might just go with some eibach dampers. Thanks for all the help guys.
 

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I personally didn't find it a fun process of changing out the suspension on my car (but some might have really enjoyed it). I'm just saying you might wait until you get the dampers as well. Are the Eibach's dampers adjustable? If not and you really want performance, you might consider an adjustable damper like the KYBs or Konis at least.
 

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if u keep the stock dampers..eibach springs would be the way to go. the spring rates are closest to the stock springs...even closer if u have an svt.

it also depends on how many miles your current setup has..if the miles are up there, it would be a wise choice to get new dampers/bushings if youre upgrading springs
 
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