Madhops

Well a couple weeks ago I installed the RB sways with my mechanic, pretty easy job to say the least. Right out of the shop the car felt a bit better with almost no roll so better steering response IMO, but also a bit stiffer over bumpy roads which was totally expected. I took the car on the track (Mission, B.C.) the following Monday and really tested things out. I'm new at this so the only other track that I've been on is Portland Internation Raceway and compared to Mission it is longer and faster with less sharp turns. By the end of the first session I was really pushing the car but felt a lot of understeer in the sharp corners. I was trail-breaking which helps but I'm still not sure if it was the shape of the track or my driving. I drove in the intermediate class, and was generally faster than most of the field which included some pretty expensive machines. So I'm thinking that the RB-Sway bars did help on some parts of the track but introduced oversteer on the tight corners compared to stock which normally very neutral in most situations.

Is there anyway to counter this oversteer problem? Right now I'm running the RB sways with stock springs+shocks and 245 Pirelli P-Zero Nero's @ 32psi on all 4 corners. So far I can't tell if the Sway bars helped with lap times (I'm going to go back to Portland later this year and compare again there). I know the autocrosser had similar results but they are only allowed to install the front bar. So I'm wondering if anybody else with both Sway Bars had similar results?

I'm thinking of getting the RB springs with Tokico D-Specs in the future.

92tsiawd

I have both bars, try playing around with tires pressures, cold tires, I normally set my tires to about 38 psi front and 36 psi rear depending on the track. More contact patch in the back means a little less understeer.

Spin9k

You need to decide which thing you felt 1st, under or oversteer, Under is the front pushing, over is the rear coming out in corners. But either way, tire pressure can do a lot for equalizing this. Try experimenting next time w/2psi extra in the front if it is pushing aka understeering, add 1 or 2 more psi if that doesn't work, but don't add too much you'll lose your contact patch, derpending on the wheel width/tire width combination. Your 245s are a bit wide for the stock wheels, so a bit extra pressure will likey help expand the tire's contact patch.

If the rear is coming out, reduce pressure a bit in that end of the car, etc. If that doesn't make you happy, consider the adj sway bar alternative, that will let you tune as you like it.

iridearocket

Your pressures are too low. Heed some advice given by the other posters as they are on the right track.

You certainly would benefit from changing your shocks and springs to a more competitive kit. RB springs may be too soft for the track and make sure you get adjustable shocks.

Playing with the tire pressures can really help find better balance. You should make the wheel alighment a little more agressive as well. The RX-8 handles great with the pressures set up and some good alignment.

Moostafa29

Get a good set of coilovers and get them dialed in to handle the way you want.

Madhops

Thanks for the replies, I'll definately up the tire pressure next time around.

Hey Spin9K, I meant to say "understeer" not oversteer, opps my bad.
So let me get this straight. If my car is Understeering (pushing) I should ADD psi to the front tires. But if it is Oversteering, I should take out some psi in the rear tires. Isn't that kind of the same thing, both methods make the front tires stiffer compared to the rear? Ok, from what I understand, to start with I gerenally need more psi all around to increase my tires' contact patch due to the 245 sizing compared to stock - so lets hypothetically say optimum is 38psi front and 36psi rear. If I add psi to any of the tires doesn't the contact patch become smaller, thus making it less sticky, so those tires with the higher psi break traction first? If my car is Understeering then wounld't I decrease psi in the front so the contact patch becomes bigger and stickier?

Quote: Spin9K -- If the rear is coming out, reduce pressure a bit in that end of the car, etc.


Quote: 92tsiawd -- More contact patch in the back means a little less understeer.
Hey 92tsiawd did you mean to say "a lttle less Oversteer"?

Anyways, thanks again to all that replied, I really appreciate it. I guess I have some experimenting to do but that's ok because I'm now addicted to track days.

Brian

Razz1

RB springs and tocico shocks or konis would be fine.

If you don't use the car as a daily driver and want to go hard core go to KW Coilovers.

Paul_in_DC

I have the Tokicos with OE springs. I like the setup I have, but RB springs would make for a lower CG, and slightly better cornering. I still have more experimenting to do with the shock tuning, but I prefer adjusting shocks to adjusting tire pressures.

Spin9k

Brian, it's a complicated event w/many factors coming into play. That's why every track race team plays around w/this area of handling. But to start, get your head around these ideas, and work from there.

First you want to start with a likely theoritical optimum psi, for our cars possibly that could be 36-38psi which is bit higher than recommended, but that psi is usually for a comfortable ride, not optimal handling. How would you guess? This is a magic number and depends on your wheel width/tire size combo - start w/the car's recommended pressure and adjust a bit for your tire width either up for bigger width tires or down for smaller width tires to have a good starting point.

So now you have a supposedly perfectly 'flat' contact patch (top of tire view like this ----). Alternatively, w/too little psi ^^ (from the top of tire view - center depressed, edges higher), or too much psi /\ (center higher, edges down).

Set correctly, your tires are all providing the optimum flat contact patch and the same grip. But go out on the track and you find some problem you want to correct for. It's not your tires, but you're either under or oversteering. Now from this optimum point of contact patch I'm saying you could either raise psi or lower psi at either end of the car to try and correct the problem.

But wait, what are those other factors that change a tire's handling characteristics? Tire carcass stability is a big one to consider and changes the 'feel' or 'responsiveness' of tire 'handling'. Raise the pressure *again, just a bit*, you'll generally increase this aspect. Lower it *just a bit* you'll generally decrease this aspect of tire 'handling'. Track temperature is another as it can automagically adjust your pressures for you. Your aggressiveness in abusing the tires is another, and then also stress and strain in the tire increases temperature, and again automagically changes pressures, even differing from one tire to the next (more right/left hand turns?)!

Putting these factors together means, within a range, you can raise the psi **somewhat** at the end of the car where you want to increase grip and responsiveness (increase oversteer/decrease understeer OR you can lower the psi **somewhat** at the end of the car where you want to decrease grip and responsiveness (increase understeer/decrease overrsteer. What's a "somewhat" change? Again a magic number, but.. lets say 1-5psi cold approx.

Remember we're taking CHANGE from the optimal psi! If your psi off to start with, well . And if you stretch the limits one way or the other too much . So that's why relatively few get it exactly right, and no one gets it right all the time! Adjust away !!

Madhops

Thanks for clearing things up Spin9K. I think I now have a good grasp on where to start and what to adjust. I'll try experimenting over the next few days and see where that leads me. Thanks again.