MrAWD

With ability to work with lots of options/parts that can be adjusted, I would agree with you 100%. But, with limited number of things that can be changed in stock class, one has to chose its poison in order to improve the front-rear balance. Balance change with FSB version improves thing on that end to move grip balance more toward the front. RSB option removes the grip in order to move balance the same way. At the end, you end up with more overall grip with FSB option while keeping the same front-rear balance.

This explanation make sense only for softer spring setup, which X describes pretty well. I don't believe IX is that much stiffer, so it should be pretty close for both versions.

Fedja

kyoo

iTrader: (29)

i must be missing something.. larger front sway bar will cause way more understeer.. i've heard of X's doing FSBs because the car is loose due to the AYC. i haven't heard of anyone doing FSB only for the 9s.

Bumpstop tuning is where it's at

MrAWD

First, thanks for kind disagreement! Not something you see a lot on public forums!!

Now, why do you think larger front bar would create more understeer? How would that apply to the softly sprung car like EVO X (and I believe EVO IX as well, even though I don't have first hand experience with those)?

And, no AYC is not a reason for Xs being loose. It is a combination of things that is greatly helped with lack of grip in the front...

DaWorstPlaya

iTrader: (31)

Ok let me help bring some clarity to the discussion. As you guys know I have the option of putting both front and rear sway bars on my EVO8 MR. I went with front based on the original A-Stock thread.

Holy oversteer Batman! Between the front sway bar, Bilstein HDs and the rear diff restack. The car was super loose initially and totally caught me off guard where I had to counter steer through some corners. I've driven stock EVOs but nothing like this. I had to relearn how to drive the car. It was seriously a blast to drive.

Turn in was quick and much more direct.
Mid corner was initially loose but I fixed that with tire pressure.
Corner exit you could easily get the car to rotate on power. That took a huge getting used to and I'm still not comfortable with it yet.

It drives more like a RWD cars than any AWD car I've driven. I've had the opportunity to drive EVO X and older STi's. I think the front sway bar also helped the car in high speed slaloms.

I haven't had a chance to align the car after making a lot of modifications so I know the toe is slightly off in the front and rear but probably pretty close. I was only able to adjust the toe on the passenger front but couldn't move the front driver toe.

Didn't do too well at the event yesterday. I was operating on 3hrs of sleep trying to get the car ready and drove like crap. 8/10ths off the guy who took 1st in BS but all the way down to 5th. The weather was in the 50s. Decent course where we hit the top of 2nd. Folks don't work on your car the night before the event.

For now, I've bolted the stock catback on the car which is heavy! I'll be able to shed some weight there. Then I have a K&N air filter I can use. In the hand of a good driver this car might be a threat.

MrAWD

That makes perfect sense! FSB on a soft car like stock EVO help to stiffen things a bit in front and that results in more grip on that end. If one would go too stiff with FSB, than it would start to push/understeer, but we are far from that in a stock trim.

Once you gain that front end grip with FSB, balance moves more toward the front and rear end starts to move around simply because front end has more grip. Due to that change in balance, rear end is not able to keep up with the front end any more, you loose the traction there first and rear end wants to come around more.

kyoo

iTrader: (29)

very interesting - this is the first i've heard where the fsb actually increases oversteer. setup sounds very potent, good luck this season!

MrAWD

Changing FSB was part of the Stock classes for a long time, mainly because that was the only option that was allowed for a long time. It worked great for most of the RWD car, but belief was that FWD and later AWD cars didn't benefit as much. But, since that was the only one that could be changed, FWD and AWD guys tried to install smaller bar to move the grip balance toward the front. They also tried bigger FSB and realized that stiffening of the front end while cornering acts close to installing stiffer springs on that end. Since most of those car were pretty soft in that department, bigger FSB kept the geometry of the front end in much better shape and that resulted in increase of grip on that end and, even more importantly, increase in overall grip as well.

But, general approach to suspension tuning is saying that bigger bar decreases grip on that end and it is blindly applied all over the place. While it is true for cases were you are already stiff, going stiffer will speed up weight transfer and result in decrease of the grip. But, for softer cars, that really doesn't apply and it goes the other way around.

kyoo

iTrader: (29)

right, after doing some reading on our own forum about fsb, it seems that at a certain point of softness, it does actually help like you said. for me, running the car in stu, i think i'll be going with caster plates first to assist in the front grip, as i already have stiff springs - though that is completely off topic.

looking forward to seeing how evos do in BS this year

Dallas J

iTrader: (1)

So many words.. TL;DR.

Cars have way to many interacting systems to really say for sure if a FSB or RSB would be better on the stock setup. If I were building a stock car I would have both and try each for several events taking notes on the feelings. If Adjustable then I would try both full stiff and full soft to get a feel for what that end of the car likes. Preferably on the same course.

Could come to the conclusion that neither is needed too.

DaWorstPlaya

iTrader: (31)

So I've driven Evos with stock front, bigger rear sway bars and they feel similar to doing just the larger FSB, in terms of rotation during steady state. But there is a slight difference in turn in. With the stock FSB the turn in isn't as crisp/direct as the front tends to flop around more. Also I noticed tire wear was much better on the front. It wasn't eating as much of the outside edge.

I didn't have to run as high of a pressure as I used to when I used to run A-Stock with street tires. This was the 1st time I've had to run higher pressure front than rear to get the car to balance out. But different temps and different surface, so I won't really know until we start our summer series. But you are correct, there is no substitute for testing.

Our next winter event is in a month weather (permitting of course), by then I hope to have the car aligned and perhaps have the lighter exhaust installed. I'll still be driving on the 6 year old Bridgestone tires I was using for the last event but it should give me a better idea of how the car behaves. Once summer season starts I'll get the newer stickier stuff and then it'll give me a much better idea of how I stack up against the local competition. By the way the guy who won the class this weekend took highest PAX at the event before (beating a few National Champs for that honors).

DaWorstPlaya

iTrader: (31)

Wow 255/40/17 Hankook RS3 V2s already sold out on Tirerack's site .... I guess I know which tire I'll be getting before the season starts.

Mario Linguini

Any thoughts on the new 2015 Audi RS3 joining us in B-Street? Vectoring AWD, more HP, 7-speed DCT, and lighter than Evo X.

http://www.caranddriver.com/reviews/...t-drive-review

Dallas J

iTrader: (1)

New rs3 is looking pretty sweet. That and the M2 are on my short list if I were to replace the evo.

MrAWD

There is no confirmation that this one would make it over here, but S3 is already here and it has my eye already as possibly replacement in the future. Already in B-street as well. Full review is here too - although might be the same thing.

DaWorstPlaya

iTrader: (31)

If the S3 is in BS. The RS3 should get an automatic bump to AS, just like the Honda S2k CR. IMHO, no way the RS3 is a BS car.