EJ_20

well, since I do a lot of hard cornering and autocossing in my 04 impreza I started to feel that my car body started to feel like the car is being soft and not as stiff as it used to be.
the only mods to the chassis are megan coilovers and 235/40 17" tires
the car now has done around 70,000 miles so what should I look up for stiffening the chassis??
I already decided to go with:
- JDM control arms
- light sub frame
- bigger front and rear sway bar (( somthing like 25mm in both ends ))
- fender braces
- group-n bushing



anything else, please guide me

EJ_20

helloO ??

LICmotorsports

iTrader: (10)

We are big fans of bushings. Group N, Urethane, or pillow ball type, we like em all.
Just keep in mind that you will start feeling and hearing vibration when you do this. When the soft stock bushings get replaced throughout the car, you might get sounds you don't like on the street.

There are bolt in cages and bars that stiffen up the chassis. Depending on passenger and cargo space needs, you can stiffen the car up to your hearts content. We love cages but most people are not willing to go that route. We have a few cage builders we work with and the options are endless.

The GD's already have the fender braces. The STi and aftermarket braces are usually lighter.

The JDM Control arms are only stiffer because of their bushings. The aluminum arms are not lighter than the stock steel ones. Funny huh!

I would never tell anyone to remove their front subframe for street purposes, as it is in place for front impact protection. I run my GD without the stock subframe. I have the Cusco V2 crossbrace designed for the Spec C (GC). I find the turn in is much better with this setup than stock. Front end bite and suspension works much better. Cusco, as well as GT spec makes a cross brace that works with the subframe. GT-spec also makes subframe replacement pieces that ties everything together, a bit overkill if you ask me.

Hope this helps a little.
-Kevin

LICmotorsports

iTrader: (10)

Oh yeah,

Bigger sway bars does not always mean better.

You might want to look at spring rates. Most coilovers do not come with high enough springs rates in our experience.

You can easily control the turn in and oversteer/understeer with spring changes.

In some cases, a coilover can ride nicer on the street with a higher spring rate.

-Kevin

EJ_20

nice infos
so anything from Group N, Urethane, or pillow ball type will work better than the stock bushing. I don't care about noise as long as the driving feel get better, but is it true that it will cause more vibration??

(( The JDM Control arms are only stiffer because of their bushings. The aluminum arms are not lighter than the stock steel ones. Funny huh! ))

?? so there is no need to waste $300 on JDM control arms when I just can the same results with just relacing the bushing


Thanx

Imprezer

iTrader: (9)

I recommend lower arm bars for the front. They will stiffen up the bottom of the car and improve your steering response. My choice would be to take off OEM subframe and install an aftermarket 4, 6 or 8 point bar on the bottom.

If you get quality brand name rear lateral links and trailing arms (e.g. CUSCO) in your rear, you will only have one RUBBER bushing left, which is your rear knuckle bushing. The part where the back end of trailing arm bolts onto. CUSCO makes a pillowball bushing for that part.

In the front, you have 2 rubber bushings on the inner ends of your control arms. CUSCO also makes replacement for those bushings and yes they are pillowball.

If you do all that, ALL your suspension bushings will be pillowball. Then, to top it off you can get pillow ball upper mounts and get STi Group N rear differential mounts and cross member bushings.

After that, you will be set...

Wingless Wonder

iTrader: (7)

With hard driving and 70k on the clock, you probably aren't imagining things. A unibody-type chassis will wear out for performance purposes from use. The factory sheetmetal will fatigue and begin to flex. The usual 'fix' is to keep making the suspension stiffer and stiffer to try to compensate but that isn't the solution. A full roll cage welded into a race-only car will extend the life of the chassis but nothing lasts forever.

Years ago, when one manufacturer used to race their econobox car model in IMSA showroom stock, they found that welding in a race cage would enable them to race the car competitively for one entire race season. Their car was just not designed with a stiff chassis to begin with so the cage in that particular car was mandatory. For street use, a full cage is dangerous without a helmet and padding on any tubing that your limbs can reach.

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