[gtpark81]

first off, i want to get rid of some of the under steer on my car and i've been looking at some aftermarket springs to help me do so....

my first question is, does the relative spring rate (relative as in when comparing the spring rate from the front springs to the rear springs..) affect understeering? for example if a spring rate of 220/160 help with understeering better than a set with 220/220? i guess waht im trying to learn is how the spring rates affect the handling of the car

also, if i were to purchase new springs, do i need to get a new set of shocks as well? im asking this because i think the stock shocks can handle new springs (such as tanabe gf210s or the tein stechs)

thanks in advance guys, i always wanna be learning new things off this forum...

[gtpark81]

MAN! ok no one responded....im sad.....

[Xman]

give it more than one workday before you get sad.

The front to rear ratio does have an effect on understeer. I think that the "understeer problem" is one that is horribly overstated. The car has a fron LSD, you should use it to power through the corners. Doing this will pull the front in a tighter line, thus eliminating understeer. This was the biggest adjustment I had to make coming from my WRX. When I would get on the gas in that mid corner I had to dial in more steering input, when I do the same with the STi, I acually have to loosen my line to avoind going off the INSIDE of the corner. Technique is much more important that running out and buying new parts because you have been told there is an understeer problem.

Once you are pushing the limits of the stock tires, alignment and suspension, then upgrade in a controlled manner. I suggest camber plates and a performance alignment first. I have Noltec race plates and I notices a big improvement in turn in and a tendency to oversteer at the limits. No bars or other parts for me yet.

Check the writeups by SEL@GP also, very well written and informative.

[Rev]

You can't supress understeer with springs only.

A rear swaybar alone would make your car more tail-happy. You can try that first.

[technica]

Originally Posted by STi_Thunder

You can't supress understeer with springs only.

A rear swaybar alone would make your car more tail-happy. You can try that first.

NO!! Do not try the rear sway bar first. This should be the last thing you should try.

1) Tire pressure
2) Suspension
3) Sway bar

Remember understeer can be a good thing, oversteer on the other hand can be disasterous.

[Rev]

What are you talking about? You have a swaybar on your car? How "disasterous" is your handling after adding a swaybar :roll:

[FT@SGP]

With the hope that I will not offend any of the previous responders, I'd like to add my opinion:

All previous responses have good advice, but I'd like to use a little different wording.

- The car has significant corner-entry understeer, but through throttle modulation can be turned into oversteer mid-corner; but that will also cause corner-exit understeer. The STi is not as balanced as it can be.

- Springs are the first items to reduce/cure understeer or more precisely adjust chassis dynamics to suit your driving. The spring rate selection is important from that perspective. For instance, spring rates 220f/160r will induce more understeer than 220f/220r springs. This is not to say that 220/220 springs is a better choice, it is dependent on the car (so do not take this as a general rule), and the driver's driving style and knowledge.

- For the STi, my personal preference would be to go with springs higher than 300# in the front and about 25 to 40# less spring rate in the rear for most purposes. Spring rates in the range of 220 to 280 at the front, won't cure understeer, but will certainly help with body roll to some extend. For the money some suggest that springs are good value, obviously you have to determine that.

- Then "fine tune" the chassis with rear anti-roll bar per driving occasion.

- One of the primary reason the STi understeers is due to significant camber gains in the front when the outside front is loaded during cornering. Increasing front camber helps a great deal, but -1.5 or -1.7 is not enough; for this to be effective you need to go beyond -2, and that is not possible without camber plates, or at least I have not tried any camber bolts that can do that.

- Also, it is suggested that changing driving styles is quite effective, and I have to agree with that to some extend. Primarily, I agree that being concious of the differentials and using them with throttle at the appropriate places is quite effective in increasing STi's corner-exit performance. Disclaimer: if you do not know how to do this already, please do not try to experiment on the street first. Try autocross or track events first, please.

[KingofImports.com]

What FT@sgp said.

Definitely experiment with tire pressure settings. We found it very useful in determining what we liked and disliked about the STi's stock handling and then found the upgraded suspension components that would improve those areas with thought were lacking. Handling preferences are usually unique to each individual, but there are only so many different approaches to improving handling. Generally, one should start with their tires if grip is a problem, start with sway bars if body roll is a problem, ETC.

[Snax]

I agree with FT 100%.

Additionally, in terms of upgrade path, you need to decide up front just how much you are going to do - both in cost, and in effort.

The rear swaybar is going to be the least expensive and easiest part to install, but if you are thinking about springs too, you should not start out with it.

If you are unsure of how much you want to invest in handling, alignment and tire pressures are where you should start. Only after you have optimized those settings can you really evaluate what to do next. Then after each upgrade you need to go right back to evaluating these settings all over again.

I highly recommend visiting a library or book store to do some reading on handling and suspension tuning. What we have discussed so far is just a small chunk of what you should know if you want to really maximize the handling potential of your car.

[gtpark81]

very interesting...thanks guys, all the inputs are very much appreciated...

in terms of handling and suspension reading material? can anyone reccomend any good informative readings on it?