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Ground Control / Koni Coilovers (incuding 2005+ STI's)
Ground Control / Koni Coilovers (incuding 2005+ STI's)
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Old 05-09-07, 05:06 AM   #1
stretch
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Default Ground Control / Koni Coilovers (incuding 2005+ STI's)

I'm starting a new thread here because, while this isn't a new product, its availability was news to me. This following information has trickled in from various threads, but all the information has been pretty buried. It was enough to prompt me to call Ground Control myself and figure out what they actually offer.

Nobody had mentioned that Ground Control made full coilovers for the WRX and STI!

Personally, I'm very excited about it- Subaru owners can now build their own premium coilovers for cheaper than the currently available big brands. Ground Control sells what is basically a fully customizable suspension setup that can be everything to everyone since you pick the parts. So, I'm sorry that I'm about to sound like an advertisement, but this is the first time I've truly gotten excited over a suspension package.

Ground Control is known for selling coil-over sleeves that you can use on your existing shocks or struts in the place of lowering springs. You get to choose your own spring rates and ride height, and if you're not sure what you want, they'll choose for you. The product looks like this, very simple:


The springs are standard sized 2.5" coilover springs, used by most coilover manufacturers. Ground Control uses Eibach ERS springs, as seen in the picture, and replacement springs are just $59. It's easy to swap springs and experiment with spring rates. You can add tender springs if want a progressive spring rate, but I'd recommend staying with the linear springs. Since the springs are interchangable on any car, I'm actually running some springs off an SRT-4 on my car (which I bought cheaply, used). I have another set of front springs in the mail, too- again, cheap and used. I know it's not for everybody, but I've been having a blast playing with my spring rates.

Ground Control also makes what I think are the best camber/caster plates on the market. They add suspension travel (only RCE plates also do this) and support the spring and strut on different bearings to distribute the load (nobody else does this). They're the only plates that add suspension travel while still offering caster adjustment. Adding suspension travel is extremely important on the stock struts since they have such a bump travel deficiency. My own experiments are showing that reducing suspension travel by just half an inch has a profound impact on ride quality.

Unfortunately, the camber/caster plates only work with Ground Control springs, but that's OK because nobody else sells lowering springs that are designed with a lowering front camber plate in mind. This is unfortunate, because it is the best way to go about lowering the car on stock struts. The availability of these camber plates gives GC owners a way of making their stock struts somewhat useful and I would recommend them prior to lowering the car (and even with them, just lowering the car a small amount).

But what I didn't know is that Ground Control also sells Koni struts in custom-built housings for the STI- even the 2005+ STI. The Koni's are off-the-shelf single and double adjustables, which are world renown and in use in motorsports around the globe. These are not the same Koni inserts sold for the WRX, although they are mechanically similar. The housings are meant to work with Ground Control's own coil-over sleeves, and when combined, you've got a complete coil-over set. WRX Koni's had a problem with suspension travel, but GC uses Koni's shortest design and have lots of travel where it's needed. WRX Koni's still work great in the rear, though, for those looking to save money (no need to buy GC housings then).

See the picture below, which I borrowed from this post.

Ground Control sells both Koni single-adjustable and double-adjustable dampers. The latter is the same part used in the $4000 Zzyzx coilovers. Ground Control sells the SA's for $159 each and the DA's for $280 each, and it's your choice. You can run different dampers front and rear or have them revalved to your spec (usually $100 each) if you like.

This means is that an owner can buy springs for their STI, add camber plates, and later convert those parts to coilovers- there's no waste. There's no selling your old lowering springs and having to learn new spring rates (unless you want to). I really like that. For guys like me, you can choose exactly the components you want, but for others, Ground Control will pick the parts for you. You don't buy parts you don't need- a full GC setup can run anywhere between $1350 and $2500, depending on what you want.

Anyway, the point of explaining all this is that I really like the upgrade path. At every step, I think GC offers the most compelling package on the market. As someone else once joked, this is the "StretchSpec" setup:

Stage 1: $400
- Get the Ground Control coil-over sleeves and springs
- For the stock dampers, 300/250# springs work great. Mark (@GC) will work with you based on your needs, though.
- Set the springs to stock ride height for best ride quality.

Stage 2: $650
- Install Ground Control camber plates up front
- Since the camber plates add suspension travel, lower the car half an inch. You will still have more bump travel than stock, making Stage 2 a significant improvement.
- Upgrade to off-the-shelf Koni's in the rear in WRX housings

Stage 3: $625
- Get Koni SA's from Ground Countrol
- Get Koni housings from Ground Control
- Lower the car much more thanks to the gobs of new suspension travel

Stage 4: $59/each
- Replace springs if desired, the Koni SA's will handle up to 600# springs.
- Mark mentioned (IIRC) liking 380/310 spring rates for a track-ready daily driver

Ignoring the price of experimenting with spring rates and sway bars, the totals for various coilover setups are:
- $1325 for a Koni SA setup
- $1675 for a Koni SA setup with camber/caster plates
- $2130 for a Koni DA setup
- $2480 for a Koni DA setup with camber/caster plates

Considering the gradual (in stages) upgrade path and that most people here only need single adjustable dampers, the value here is simply incredible. But for you big spenders, the double-adjustable setup is similar to the Zzyzx coilovers for $1500 less!

Anyway, discuss. What do you think of the package? The only member here that I know runs a full setup is xtremeyolks, who has the full DA package. Anyone else using full GC coilovers? Have any advice to share?
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Last edited by stretch; 06-01-08 at 06:33 PM.
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Old 05-09-07, 05:28 AM   #2
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Default Re: Ground Control / Koni Coilovers

Once again stretch comes thru with more invaluable suspension information for us. Thanks for all the leg work stretch.
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Old 05-09-07, 05:29 AM   #3
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Default Re: Ground Control / Koni Coilovers

Thanks for putting this information all together. It looks like an excellent way to go for "cheap" with a race-proven damper.
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Old 05-09-07, 06:22 AM   #4
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Default Re: Ground Control / Koni Coilovers

Stretch - Thanks for all the great research. Couple of questions for you. Do you reuse the stock dust boots? Did Mark recommed that you get the Koni's revalved?
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Old 05-09-07, 06:37 AM   #5
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Default Re: Ground Control / Koni Coilovers

It's very much a work in progress for me at the moment, so no, I don't yet have any dust boots. The stock ones will not fit because they're too wide. There are some cheap universal ones out there that I may try.

Mark said the basic valving works great- that the Koni's come set up for a default weight of car. So, you're getting generic valving, but valving that is already tailored to the correct weight vehicle. Mark didn't mention revalving his own struts- he has an 04 STI.

One other thing to consider is bump stops. The stock ones will not fit on Koni's since the Koni shaft is three billion times thicker. If you're using WRX strut housings in the rear, try to get the WRX bump stops with them, since they fit. Cut the bump stops in half (they're much too long), and now you have your front and rear bump stops! Put the soft progressions up front. Otherwise, GC sells those too.

Last edited by stretch; 05-09-07 at 06:49 AM.
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Old 05-10-07, 06:01 AM   #6
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Default Re: Ground Control / Koni Coilovers

I'd echo strech here and say that you should not need to revalve the Koni's in our cars. My race car uses the SA Koni Yellow's with 475 front springs (i would not go over 450-475lbs though) and ~300lb rears, and at 2950 its a heavy mofo as well

Koni has some great valving in their shocks and I might actually think about putting these on the subaru for a better setup... but we'll see... house > race car > street car.
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Old 05-10-07, 06:04 AM   #7
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Default Re: Ground Control / Koni Coilovers

I was actually just looking at Zzyzx's web site, and it doesn't mention custom valving either. I think they're using off-the-shelf valving too. (Of course, revalves are always optional on any Koni.)

The main difference I see between the two setups is that Zzyzx uses a threaded strut body... but I *think* GC may use a shorter overall strut to maximize bump travel. In either case, both look like they'll have boatloads of travel where needed for most ride heights.

So, this really does appear to be (in my eyes) a Zzyzx setup for much less money.
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Old 05-10-07, 06:07 AM   #8
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Default Re: Ground Control / Koni Coilovers

Quote:
Originally Posted by stretch
I was actually just looking at Zzyzx's web site, and it doesn't mention custom valving either. I think they're using off-the-shelf valving too.

The main difference I see between the two setups is that Zzyzx uses a threaded strut body... but I *think* GC may use a shorter overall strut to maximize bump travel. In either case, both look like they'll have boatloads of travel at most ride heights.
I've always said that Zzyzx's are WAY to expensive for what you get. a long time ago i remember them saying they can do custom valving at an additional cost
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Old 05-10-07, 10:27 AM   #9
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Default Re: Ground Control / Koni Coilovers

Got a damper dyno for the Koni SA and DA offerings?
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Old 05-10-07, 01:36 PM   #10
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Default Re: Ground Control / Koni Coilovers

The Zzyzx Koni DA and WRX Koni insert dynos are here: https://www.iwsti.com/forums/showpost...92&postcount=4
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