I'm thinking of buying the Whiteline 24mm adjustable rear bar to go with my Prodrive springs and stock struts on my '05 STi. My goal here is to lessen or eliminate the nasty understeer that the car has from the factory. Has anyone had any experience with this combo?

 

a stiffer rear swaybar won't really reduce understeer as much as increase the tendancy for oversteer.

i'm sure sybir will chime in and correct me if i'm wrong.

 

Nope, that's it.

 

care to elaborate on the difference between decreasing understeer and increasing oversteer?

 

reducing understeer means the front end gets more grip.
increasing oversteer means the rear end gets less grip.

the two can feel similar but are definitely not the same. reducing rear grip on a car that already has poor enough front grip to understeer can result in less overall grip and lower handling limits than before.

 

not only that, if you don't match with the right front sway (note, i'm not saying that the front sway you already have won't match well with this rear one that you're looking at), the tendancy towards oversteer can be pretty dramatic, and even outright dangerous! exactly how dramatic is determined largely by the difference in size between the two (there's other factors too though, especially with adjustable ones).

that's just the basic stuff though, this discussion could go WAY deeper than this.

 

http://www.iwsti.com/forums/showthread.php?t=47158

http://www.iwsti.com/forums/showthread.php?t=26301

thatll help more than any of us trying to explain it to you.

i went with a whiteline 24mm adjustable bar up front and have the stock rear and the car is very neutral, it doesnt have the snap oversteer i would experience in my bugeye which had the stock front bar and aftermarket rear, which would still understeer BTW, until the rear end flew out. wasnt very confidence inpiring, LOL. on my STI the front end is planted and the rear just follows it, TONS of grip.

 

Explain. What is the best way to get the car to handle better and not push so badly?

 

To reduce understeer, you add front grip.

 

So I'd be best off buying a matched pair.

 

exactly true.

and why i swear by a bigger front bar in the STI. a lot of people with stiff suspensions, like coilovers and such actually had to REDUCE the size of their rear bars for optimal handeling.

 

... and the best way to do that is?

 

read the 2 links i posted for you. they will sum it up perfectly.

 

Thanks, Justin. The Siegel Racing site was very informative.

 

Lots of ways. More camber, bigger and stickier tires, proper lowering, stiffer springs, stiffer front bar, front end weight reduction. You name it.