STi/Prodrive/Bilstein Suspension confusion

Discussion in 'Subaru Impreza WRX Help & advice' started by Andrew Cook, Feb 14, 2019.

  1. Andrew Cook

    Andrew Cook Cookie

    Hi from Australia.

    I've recently come across a few of the STi/Prodrive/Bilstein suspension setups and am very interested in them, however I'm totally lost with it all...

    I've been trying to read up heaps but most of what I'm finding is through American forums and is only making me confused! They seemed to have some upgrade options in their market which included whole sets or just springs on JDM v5 STi struts, so I can't figure out how valid that info is... I'm hoping someone on here knows about it all and has all the info to lay it all out clearly for me...

    So I've seen variants of the silver struts with the "STi Prodrive Bilstein" labels on them; blue springs, at least one type of blue set with Eibach stamps on them; silver springs, no idea who makes them; and also red springs, one of which set I've seen with the P1 stamp on them. I've also heard of WR, GT and P1 packages. - I've just seen a "Eibach Pro-kit" spring upgrade too, they were red springs but I also saw Eibach pro springs referred to as being black...

    On this site, I saw a set of STi Prodrive Bilstein struts with Eibach blue springs that is supposedly what came out on the UK 22B, and had also mentioned the P1 model.
    - is the suspension that was fitted to the UK sold 22Bs different to what was fitted to the JDM 22Bs? What did the JDM 22B come with if so, red struts with black springs? Were they even inverted type struts?
    - What suspension did the UK P1 come with and where does it fit in, is it just a spring change or struts as well?

    Other info I read suggested that there were separate 97-98 and 99-00 versions of the "STi Prodrive Bilstein" suspension with different specs, although were all inverted style struts.

    Can someone please lay out for me (if the info is available) what variants/combinations of all of these STi/Prodrive/Bilstein suspension setups there were, whether or not they're inverted struts, their dampening stiffnesses, their spring rates and whether or not the springs are progressive?

    If straight numbers aren't out there, then at least order them from softest to stiffest, but also including JDM MY99 v5 STi & JDM MY00 v6 STi suspensions in there for comparison as a known reference. Any height ride differences are given for these setups compared to the JDM v5/v6 STI for a sedan would also be appreciated...
    - I have a MY93 Liberty GX Sedan with JDM v5 STi suspension and a MY91 Liberty RS Sedan with JDM v6 STi suspension for my reference. I believe the struts are the same but the springs are slightly stiffer for the v6 than the v5...

    Thank you very much!
    Last edited: Feb 14, 2019
  2. tekkerchrede

    tekkerchrede V-Limited Member

    @2pot will probably be around to explain, but WR97/98 is blue springs (all dampers are silver) - I had a set for sale in the shop on this site. WR99 is grey springs (actually more boring colour combination). The difference in ratings are listed in several places spread out over the forum. Red is used on some 22B's I believe and also the P1, at least those made by @2pot as an update/new production batch.

    Maybe we should have this suspension thread, @type-ra? Could include the S201 abd Showa STi suspension too.. :thumb
  3. 2pot

    2pot V-Limited Member

    WR97/98 inverted Bilstein with Eibach blue springs - too low, too soft. Rear strut short.
    WR99/GT inverted Bilstein with Eibach grey springs 35N/mm front and rear. Kit included an 18mm rear bar to replace the oem 20mm. The WR99 Bilstein struts were eventually sold off, by Prodrive, with P1 springs - not necessary to reduce the rear bar.
    P1 - KYB inverted v5sti/v6sti red struts, with softer, red, Eibach P1 springs (34N/mm front, 27.5N/mm rear ) for b-roads - Rock-hard oem 60mm front bump stop in v5sti/v6sti struts, as a form of pitch control - better when changed for a softer, more progressive, front stop with shorter, stiffer, rear stop.
    JDM 22B Bilstein inverted struts. UK22B softer springing/adjusted damping, still Bilstein inverted strut.
    If the spring has coils that stack together, then it's progressive. But, if the coils have all stacked, say 15mm before the ride height, to increase the spring-rate, then the spring can be made linear in its operational range.
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