WRX suspension trivia
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This is a discussion on WRX suspension trivia within the Suspension & Wheels forums, part of the Tech & Modifying & General Repairs category; Thought I'd put together a few tidbits learned along the way. These deal w/ the new age sedan (GD). People ...

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    Moderating on the run! Big Sky WRX's Avatar
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    WRX suspension trivia

    Thought I'd put together a few tidbits learned along the way. These deal w/ the new age sedan (GD). People often what differences in suspension are there between the WRX, STi, STI RA (or RA spec C). In 01 it was RA, 02 RA spec C, 03 spec C- all the same.

    Struts

    WRX non-inverted, 22mm piston
    STi inverted, 40mm piston
    RA inverted, same strut (same part #'s)

    Springs

    WRX 168 front/119 rear (MT)
    STi 188 front/173 rear
    RA 217 front/ 190 rear

    Tops

    All have the same tops. I found this interesting as many (including myself) thought the STi and RA got firmer tops. The only firmer tops are the Group N- which are aftermarket STi.

    Big Sky

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    Registered User WRC_Obsessed's Avatar
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    this is great stuff...thanks for putting it in one place...
    -Brian

    Twisty Monster - 335 ft/lb of torque @ 3600 rpm on a stock turbo. Is that possible? Yes it is.

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    Moderating on the run! Big Sky WRX's Avatar
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    No problem. There has been so much specualtion (myself included) on different oe setups, it was nice to get it squared away finally.

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    Registered User WRC_Obsessed's Avatar
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    for the RA you say "same strut"...is the RA strut the same as the sti or wrx?
    -Brian

    Twisty Monster - 335 ft/lb of torque @ 3600 rpm on a stock turbo. Is that possible? Yes it is.

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    Moderating on the run! Big Sky WRX's Avatar
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    RA same strut as STI (40mm inverted).

    Big Sky

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    Registered User djrez4's Avatar
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    What's the difference between the adjustable and non-adjustable STi struts? (besides the adjustablility )
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    Moderating on the run! Big Sky WRX's Avatar
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    The adjustable ones are the STi sport (aftermarket) ones- they're also pink (actually cherry blossom). They both share the 40mm piston and inverted design as the oe STi/RA ones.

    The are one adjustable (bump/rebound together) w/ four adjustments. The damping rates overlap the rates of the STi/RA struts- higher and lower. Setting two in the front and three in the rear most closely "mimic" the oe STi/RA strut rates.

    They are very nice, but expensive. Most people who get these go w/ the sport springs- lower ~ 1" w/ 200f/185r rates.

    Big Sky

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    How 'bout them wagons?

    If it's handy, could you throw in the New Age Wagon (GG?) strut/spring info? I guess that would include: WRX, and STI (SPT kit) since there is no RA wagon, right?
    Thanks,
    B

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    Big Sky, GV27 or anyone else with answers,

    Couple of questions on STi Adjustable struts:

    1) Can the struts be teamed with the regular STi springs with slightly lower spring rates (than STi Lowering) and no drop? If so, how much performance am i giving up by going with standard STi versus Lowering STi springs?

    I would want a softer set of springs so that I can go over bumps at stupid speeds (i heard comments about RA and lowering springs being too harch for bumpy roads... at least unpleasant). The STi regular springs are softer than lowering and maintani the same 92% rear ballance. +higher clearance may be better in cases.

    2) What are the settings on the adjustable shocks that would give me the same soft feel of a stock WRX suspension?

    There are settings that may be useful on really bad roads, gravel and low traction situations like snow.

    3) Going off of your setting 2 in front, 3 in back comment for neutral handling, does this mean 3 in front, 4 in back is the highest I can go on the shocks and maintain a more or less neutral handling balance?

    In other words, why are the shocks not valved such that setting 4 in front and 4 in back would result in very stiff and neutral handling. instead of staggered numbers like 4 and 3. Considering these shocks were specifically made for the wrx application, would this make sense?


    Thanks guys!

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    Moderating on the run! Big Sky WRX's Avatar
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    Bart- the SPT kit for the wagon (GGA) is the oe setup for the GGB (STi wagon) as you are correct there is no RA wagon version. Spring rates are lower than the RA at approx the same as the sedan STi ~ 188/173.

    vano- the struts can be team up w/ the "regular" STi non lowering struts as theya re the same struts that come on the "regular" STi. You are correct the rates are lower than both the RA and sport setup and no lowering- this would make a "softer" setup- better suited for gravel for sure (softer/nonlowering). They do maintain a "better" ratio, front to rear, for more neutral handling.

    There are no settings on the adjustable shocks that would match the damping of the oe WRX struts. The lowest settings are higher than the oe struts.

    My statement on 2 front and 3 rear was simply pointing where the adjustable struts would have to closest be set to duplicate the damping in the non-adjustable STi struts. One be the softest setting, four the firmest.

    Here are the rebound/bump #'s for the STi/RA strut:

    front 2396/791N @ 0.3m/sec
    rear 1668/690N

    Here are the #'s for the STi sport adj:

    1 2 3 4
    front 2320 / 790 2450 / 830 2650 / 870 2940 / 950N @0.3m/sec
    rear 1470 / 610 1530 / 640 1650 / 660 1830 / 700

    This rather firm rear setting for the oe strut also contributes to dialing out some understeer.

    The obvious advantage to the adjustable struts is they allow "softer" settings to be used day to day and "firmer" for performance orientated duties. They also let you play with damping settings front to rear, influencing handling.

    Big Sky

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    Thanks Big Sky,

    Sorry if I am asking a question that already has answers posted on the forum (wasn't able to find it): what are the rebound rates for stock US WRX shocks?

    I guess I am trying to determine if what kind of handling balance I would get if i had STi Adjustable Struts and STi springs and incremented the shock settings evenly ie: 1-front / 1-rear for daily driving and 2-front/2-rear or 3-front/3-rear for spirited/autoX.

    I am also considering getting Group N camper/caster plates and dialing in aggresive settings in the front.

    Would i be able to do 1 for 1 increments on the f/r shocks like that and still maintain an overall neutral handling balance, or would the car be understeering pretty bad?

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    Moderating on the run! Big Sky WRX's Avatar
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    I tried and tried to get the oe damping rates from SOA- to no avail .

    The settings you'll have to play w/. 1/1 might work best for some applications, 4/4 for others, 2/4 for others, etc- a lot will depend on how your car is setup, the application and your preferences on handling. A lot of the neutral handling is already achieved by the spring rates- they are much closer together front/rear vs oe- this will dial out understeer.

    There is no "official" Group N caster/camber plates, but if you look in this forum I'm setting up a group buy for the Noltec (AU) caster/camber plates- if interested we're likely ordering this week. They will be priced close to $100 off normal prices.

    Big Sky

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    Springs

    What about springs?

    The choices are:

    STi RA - may make the ride too stiff for me. Want to be able to take the bumps without having to slow down.

    STi Lowering - I like the spring rates on this one, and they seem to be made for the STi adjustables, but the 2 inch drop means reduced suspension travel and possibly messes up the geometry. Are these assumptions true?

    STi Sedan - these springs don't drop the car, are stiffer than stock and have pretty good front/rear balance. I guess my concern with these springs is that, i may be giving up some handling performance like steering and body lean because they aren't all that much stiffer than stock. Also, the adjustable STi struts operation range (the upper limit like setting 4) seems out of the range of the springs.

    So i guess my question is: how much handling performance am I giving up by going with STi sedan, instead of STi lowering springs? I wish someone would make springs like the STi lowering ones that lowered the car between 0 and 1 inches. That would be perfect.

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    Moderator GV27's Avatar
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    STi Lowering - I like the spring rates on this one, and they seem to be made for the STi adjustables, but the 2 inch drop means reduced suspension travel and possibly messes up the geometry. Are these assumptions true?
    No - they don't lower that much. STi says 3/4" but a lot of people report 1" - 1 1/4". As far as lowering goes I don't think anyone makes a spring that lowers less. A lot of people have good experiences with them on either stock struts or STi struts - or Konis.

    So i guess my question is: how much handling performance am I giving up by going with STi sedan, instead of STi lowering springs?
    22.732

    of course that's just an estimate. It's subjective.

    I wish someone would make springs like the STi lowering ones that lowered the car between 0 and 1 inches. That would be perfect.
    Don't know about "standard" STi springs but RA and Lowering are about in this range. People with the RA springs report anywhere from 0 to 1/4" (BigSkyWRX w/ STi struts) to 3/4" (me w/ Konis).

    edit: BTW a lot of people report a very comfortable ride with RAs. My Wagon with RA springs and Koni struts has a much smoother ride than stock. You feel the big bumps more but they are smoother - it's hard to explain. My setup takes away all the harshness that was there before. You still feel the small stuff and you probably feel the bigger stuff more but it's just WAAYY smoother. It doesn't isolate you from the road but at the same time is much plusher. The big 3' wide speedbumps in my neighborhood have become "yumps" to launch off of.

    See this thread:

    STi RA Springs/Koni Strut Insert initial review.

    People report the same thing with the full STi RA setup.

    Chris
    Last edited by GV27; 05-01-2003 at 02:02 PM.
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    Moderating on the run! Big Sky WRX's Avatar
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    If your going w/ the STi adjsutable struts, I think any of the STi springs would work fine. Chris is right the STi lowering springs are a pretty mild lowering really about 1-1.25".

    If you want a softer ride (for comfort or gravel) than the "normal" STi springs would probably be best. No lowering obviously. Although the front rates are only 12% higher, the rears are close to 50% higher. Bringing the rear rates up closer to the fronts will impart a much more neutral feel.

    I would guess that if one spent the time sourcing these springs form japan/uk/au you could find them cheap!

    I wouldn't worry about being over damped w/ this spring, much better than under damped.

    Big Sky

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