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Discussion Starter · #1 ·
I know the difference in looks between a Progressive spring and a Linear spring.

What I want to know is if you had two identical stock WRXs, and one had progressive springs and the other had linear springs, what would the differences be?

Would the differences be noticeable in daily driving, or just spirited driving? Is one type better than the other at reducing understeer on a stock WRX?
 

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Discussion Starter · #2 ·
Spring Rates

I am looking for the spring rates of the Eibach ProKit and the Prodrive springs. The springs will be for a stock WRX. Which, if either, of these two springs would help reduce understeer more?
 

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Merged threads.

Well, there is a bit of disagreement on the Eibach spring rates. Big Sky says 188 front/ 160 rear. Ravensblade says 177 front, 91-188 progressive rate rear. Do a search. Call Eibach - they can tell you for sure. Please post your results.

The Prodrive rates are secret. You won't find them anywhere. They are said to feel a lot like the Eibachs, so the rate is probably similar, though perhaps a bit softer. The Eibachs are very progressive, while the Prodrive are linear.

Which is better at reducing understeer? Hard to say - I've yet to hear from anyone who has driven both at the limit. My guess would be Prodrive, as the linear rate should improve initial turn-in which in turn should reduce the tendancy to understeer. This depends on your corner entry technique, however - people who like to flick it in hard will benefit from the linear rate more than people who take a less aggressive approach to corner entry.

In general, a progressive spring will ride a bit nicer, and perhaps perform better over small bumps and high-frequency undulations where the lighter initial rate helps soak that sort of thing up. A linear spring will in general ride a bit rougher but respond quicker to driver inputs.

Hope that helps. Do a search for more info.

Chris
 

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The Eibachs are definitely progressive, my #'s (which I've found many others that are somewhat close) are the linear #'s. The Prodrives are also made by Eibach, but as Chris pointed out likely not to find much out about them.

With lots of twists and turns (autox) progressive springs will be at a disadvantage IMO, too much transition back and forth vs a linear spring. Progressive springs vary greatly so its hard to give a pat answer- the vary in there progressive rates and how many coils there are, they vary in where the progressive winds are- top or bottom,there are also double progressive springs (winds top and bottom- my DMS had these). As Chris mentioned progressive springs are generally more comfortable to ride in and if well designed lose little in the way of performance.

Big Sky
 

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Spring...........................................Front Rate...............Rear Rate
Stock 1998-2001 2.5RS......................157........................149
Stock 2002 2.5RS (MT/AT)...............149/158...................117/129
Stock 2002 WRX Sedan (MT/AT)......163/163...................119/132
Stock 2002 WRX Wagon (MT/AT).....163/163...................132/144
GDA STi Sport Springs.........................200..........................185
SPT/STi ............................................217..........................190
Prodrive P1.......................................215..........................195
Eibach...............................................171.......................91-188
5Zigen.........................................169.3-225.7...............79-180.6
Tein Soft......................................67.2-179.18........61.59-179.18
Tein Medium................................67.2-235.18........61.59-218.38
Tein ...............................................307.98...................279.98
H and R Sport..............................196.25-204.1......186.25-193.7
STi Version 4........................................196........................174
STi Version 5........................................224........................185
STi Version 6........................................237........................195
STi Version 6 Tarmac/Gymkhana...........286.......................274
DMS 40mm Street/Gold.........................225.......................180
DMS 50mm Rally..................................275.......................225
DMS ..................................................700.......................650
DMS 60mm Super Strut........................260.......................200
Whiteline Progressive Lowering.............190.....................150-170
 

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Me thinks that post from flat four justifies a sticky. Good stuff!

Jimbo
 

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It already is in the Tech Reference sticky.

I'm actually thinking of recompiling that list. Some of those are suspect, including Eibach (some disgreement there) and the fact that the Tein rates are for coilover springs, NOT the "regular" springs, and that really confuses people.

Chris
 

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Here's Tein coil-over rates if these are what you are talking about.

Car................Coil-over..................F/R........................R/R
Wagon............Wagon...................280.........................168
Change Rate.................................Both.........+ or -......-56
Sedan..............RA..........................448.......................336
Change Rate.................................Both.........+ or - ......112
Sedan...............HG........................252.....................106-196
Change Rate....................can't find
Sedan...............HA.........................392......................336
Change Rate..................................Both.............+ or - 112
Sedan................SS........................280......................280
Change Rate.................................Both..............+ or - 112

Now since these are REAL coil-overs you can change the spring rate as well which are + or - there normal rate


FF
 

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Could you elaborate on that a bit? I'm not sure what that chart is telling us.
 

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I changed it so it easier to read.

FF
 

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Jimbo said:
Me thinks that post from flat four justifies a sticky. Good stuff!

Jimbo
Methinks flat four should at least give ravensblade-impreza.com due credit for compiling that list in the first place and letting him cut and past into his post.

Oh yeah, Prodrive P1= GC body Impreza springs. I'm not sure if the GD Prodrive springs are the same spring rate, it's still a mystery.
 

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supermarkus said:
Methinks flat four should at least give ravensblade-impreza.com due credit for compiling that list in the first place and letting him cut and past into his post.

Oh yeah, Prodrive P1= GC body Impreza springs. I'm not sure if the GD Prodrive springs are the same spring rate, it's still a mystery.
The P1's are definitely a higher rate then the GD springs. The P1's are possibly a smidge stiffer than the GD RA springs. The P1's came w/ their own strut (an inverted 40mm, much like the GD RA). By Prodrive's account the GD springs were designed w/ the oe strut in mind, but most are finding out they actually do better w/ a heavier damped strut ala Koni, KYB AGX, some are even using them w/ the STi v7 strut.

Still kind of miffs me they won't make the spring rates public, although most of the strut manufacturers won't let out their damping rates either. I still think it would be great for a car mag to take a bunch of these springs to get tested, as well as a bunch of the struts and put them on a shock dyno- inquiring minds want to know.

Big Sky
 
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