good summary that perfectly sums up why the RSB is the correct choice (with the bolded part I added). when a car understeers (like a stock evo does) it means it already has too much rear grip so trading away rear grip for more front grip is the correct answer.

the limits on stock front camber (only -2*) and street tires prevent us from having to consider the higher end of the lateral grip spectrum where the inside rear lifts off the ground too early. that (excessive inside rear lift) is when the tables shift towards FSB being the better choice.

 

Completely agree with the rear sway bar for the pushing problem, with the limited mods allowed for bs class the stiffer rear sway bar is going to help the car rotate better than a stiffer front sway bar.

 

Btw would you guys critic my run. I am running in street b at my local autox

 

I think that Prime12 sum it pretty well, and here is similar view of the situation. The main reason why car is more balanced with RSB is because stiffer one makes that side to loose grip sooner. The only change is in grip balance (which is better than stock for sure), but overall grip on each corner is not improved. So, yes, you should be able to get better times compare to the OEM setup, but not as much as you would benefit from the front bar.

FSB increases stiffness in the front, which aids dynamic camber values, so the values don't get affected as much as stock car does. Since all of stock EVOs (here in US that is) are pretty soft (especially in the front), FSB will improve this a bit. We are still far from the stiffness that would start to lift inside front by far. If we would have such strong FSB that would not bend at all, end result would be double of the spring rate on outside tire. EVO X doesn't even have 200 lb there, so you would still be under 400 lb of spring rates where car has over 1,200 lb of static weight (again, numbers for EVO X), plus all of the weight transfer that happens. To keep things in good shape, you would need much more spring in there to start thinking of lifting that inside front.

So, to finalize, with FSB you would increase the front grip from the OEM setup, but without the loss in rear grip which comes from RSB. With increased front grip, balance is improved the same way as with the RSB - basically, you have increased front to rear grip ratio. But the major difference is that overall grip is also improved, which is better than what can be gained with RSB change. At the end you have OEM slower than RSB, and RSB slower than FSB.

Fedja

 

I will try this one...
Course is pretty tight and looks like some parts are meant for Miatas only! You have shifted few times into 3rd and it doesn't looks like you were benefiting from those. I have a feel that you would save some time by staying in 2nd for those.
few places you were turning too early which made you to slow down more than you should. By given yourself a bit more space on the other side you would be able to go through that gate with higher speed (that is at 39th sec mark). You also went to 3rd few gates before the finish and I also think you would be faster through that section if you kept 2nd a bit longer if not all the way through (this one is hard to say). Also, because of so much shifting you were hanging your right hand on the sifter more than I would like to see it on your steering wheel.

 

Thanks i have tried to ride out 2nd gear through some of the gates but felt like i was slower. Thanks for the input next month the course will double in size. I have the fastest times that day for the "door slamer" vehicles by 1.5 seconds.

 

Physics doesn't agree with your theory. Your explanation of how swaybars work is not correct.

 

No problem there!

 

I'm assuming:
RSB reduces roll, which promotes rotation, which helps balance the chassis. (Roll+balance).
FSB helps reduce roll but will promote understeer even more. (Roll only).

 

this thread makes me wish my evo were still in BS!

Fedja, it might just be as simple as, the older cars, with lack of AYC and ability to change that in BS, get more benefit out of a RSB than a FSB, and the X, with AYC can make better use of a FSB.

The older cars drive more like FWD, and I don't know any FWD that's opted for FSB over RSB. For FWD cars, the looser the better in autox. On the Mini I've got a bar that is 400% stiffer than stock and very stiff bumpstops, and the car handles extremely well.

 

Excellent point. Crap I forgot about AYC. in that case, I can't say. I've never built a X.

 

You would be surprised how many FWD cars change FSB in street and previously in stock...and all of that because more stiffness where the car is the heaviest, helps more than just better balance with looser rear end.

I think I will close this with something Andy Hollis wrote today on other forum:
"One of the things I stress in my MSX talk about testing is to be a skeptic. Gather as many data points as possible, filter them based on their source and applicability to your situation, and use them as guidance in your own testing. Always be testing.

I don't even believe my own data, as far as being a "final conclusion". I look at it as narrowing down the choices to an ever-smaller range (not just talking about tires here, btw). For months, I'll be carrying around the top two sets/sizes of tires and trying them again in different situations/combinations/setups.

And if all that is too much for you, simply make a choice, stick with it, and develop your car/setup/driving around it. A synergistic combination will beat the "right tire" on the "wrong setup" every time."

 

^100%

 

I stumbled onto this as I was hanging out at CBRD this weekend. It's a Best Motoring comparison between the IX and the X on a very tight track. (Keep in mind, I don't know what the exact model options are on these cars, what tires, ACD, AYC, SAWC, etc because I do not speak Japanese ) Start at 49:48.

You can hear "understeer" when he is driving the IX Some words translate very well.

IX: 23.0
X 5MT asc off JV-= off: 22.4
X 5MT asc off JV-= on: 22.1

Any idea what the JV-= is?

Anyway I was just really surprised that in a course designed to punish understeer, that the X was so much faster. I guess the magic computers work pretty well.

Street tires are not race tires. I don't think any of those old datapoints really apply here.

 

Couldn't agree more with you on this! It would be much better to know Japanese for this one!!
I though this is for AYC brake mode, aka. two steps traction control that X has.

Since you are going back there, most of my autoX experience comes from 1996-2002 and during those times tires like Victoracers were winning some of the races. If you would take top street tires of today and compare them with that Kumho model, I think they would be pretty close!!