STX Rules and Setup Questions

[smg1138]

Originally Posted by DocWalt

I'm still at -2.6/-2.0 camber front/rear. Rear tire wear is definitely biased a bit towards the outside on track, but no issues at autocross. I do get a bit higher outer shoulder temps, but not more than ~5 degrees F.

What hot pressure are you running?

I was running 34 front and 32 rear last event. I never hit the triangles, but when I took the wheel off the outside wear was pretty noticeable. Here's a pic of one of the rear tires. Both sides are basically the same.

[cjd]

Such high pressures! I've never done over 30, as low as 26...

[DocWalt]

Triangles aren't the indicator of how far to roll the tire over. You should see a color change from tread rubber to sidewall rubber, aim there.

I'm running 28 hot in the rear, similar-ish wear. You'll wear the center rib at a taper when you really start using the tires

[rx3]

Originally Posted by renfield90

Looks pretty loose - is that a personal preference, or a consequence of damp/drying conditions?

No, that's what KW recommended. (It's actually pushy at corner entry, loose mid corner and stabilizes as soon as you hit the throttle.)
However, this was a practice run on road legal tires.
I told them that I'm running on slicks (I had to fill out a form where I needed to tell them the exact application) and on slicks it's not loose at all (exact same setting). I still think it's too stiff for an autocross application - they probably just sold me their 'Nordschleife-kit'.
But then again, it is fast (according to the clock).

[renfield90]

Originally Posted by DocWalt

Triangles aren't the indicator of how far to roll the tire over. You should see a color change from tread rubber to sidewall rubber, aim there.

Yup.

Just in case this needs reiteration for people: triangles indicate there is a wear bar at that location on the tread.

Triangles don't mean anything about the end of the tread cap and the beginning of sidewall rubber. In fact, where it is in relation to the tread cap will change across different models of tire within the same manufacturer, let alone across different manufacturers.

A lot of people use the triangles on the RE-71R because by coincidence it gets you into the ballpark. But it's fundamentally not the right way to evaluate how far you're rolling over. Future production runs of the RE-71R could place the triangles in a different spot. Imagine yourself lowering pressure more and more to hit the new triangles spot, and thereby setting yourself up to chase your setup for months thinking "I got the tire pressures right, so what changed on the car?"

Interestingly enough the tread cap on the Rival S with those big massive shoulder blocks that *look* like they should tolerate plenty of rollover is pretty high up, such that a very large chunk of the shoulder blocks is actually not the rubber you're looking for.

[smg1138]

Thanks to everyone for the feedback. I guess I was misinformed about the triangles. I'm going to try a little more rear camber next time and see how that does. Really glad I got those adjustable lower control arms now.

[AFRichZC6]

Does anyone here consider natural frequencies when choosing spring rates?

I'm considering joining STX next year.

[smg1138]

Anybody running the stock swaybars in STX with success? Right now I've got a Whiteline 20mm front bar and I can't get rid of the popping sounds. It performed great last time out, but the noises are driving me nuts. I already replaced the endlinks with shorter ones that I got from Feal, but the pops still persist. I'm wondering if maybe putting the stock bar back on and removing the rear bar might be the way to go? Either that or try the Strano bar maybe.

[DocWalt]

No issues with my Whiteline bar. That I'm aware of anyway, though I get popping from the right front I'm pretty sure it's spring bind on the perches as it makes a nice "boing" sound occasionally. I've been too lazy to take it apart and lube the tophat perch again. Have you tried just unbolting the end links and seeing if it's the coilovers?

FWIW I was tempted to try stock front swaybar and unhook the rear. As I've gotten faster I've found that I still have a good deal of roll in transition, even with the whiteline front bar so I'm not sure I'd want to try that now. I've not noticed having to wait for the car to settle, but if I'm literally toeing the line between waiting for roll and not waiting... That said, I am somewhat softly sprung, 60N/mm front & 70N/mm rear (343/400 lbs./in.) so take that with a grain of salt.

[Stang70Fastback]

Originally Posted by smg1138

Anybody running the stock swaybars in STX with success? Right now I've got a Whiteline 20mm front bar and I can't get rid of the popping sounds. It performed great last time out, but the noises are driving me nuts. I already replaced the endlinks with shorter ones that I got from Feal, but the pops still persist. I'm wondering if maybe putting the stock bar back on and removing the rear bar might be the way to go? Either that or try the Strano bar maybe.

I've won my class in both of the Chicago SCCA events so far on stock swaybars with my soft KW V3s (though STX in Chicago region doesn't seem terribly competitive at the moment), and I came second in the TSSCC event this weekend (0.7 seconds behind a FULLY prepped BRZ, whereas I have basically coilovers and tires.)

Having said that, I find the car rolls too much for my liking and would like at least one of my bars to be stiffer in the long run.

[smg1138]

Originally Posted by DocWalt

No issues with my Whiteline bar. That I'm aware of anyway, though I get popping from the right front I'm pretty sure it's spring bind on the perches as it makes a nice "boing" sound occasionally. I've been too lazy to take it apart and lube the tophat perch again. Have you tried just unbolting the end links and seeing if it's the coilovers?

FWIW I was tempted to try stock front swaybar and unhook the rear. As I've gotten faster I've found that I still have a good deal of roll in transition, even with the whiteline front bar so I'm not sure I'd want to try that now. I've not noticed having to wait for the car to settle, but if I'm literally toeing the line between waiting for roll and not waiting... That said, I am somewhat softly sprung, 60N/mm front & 70N/mm rear (343/400 lbs./in.) so take that with a grain of salt.

I'm pretty sure it's not the coilovers that are causing the noise. I'm familiar with the spring binding "boing" noise, but this is totally different.

Before installing the Whiteline bar everything was dead quiet. It's only since I installed the bar the noises started. I thought the shorter endlinks would do the trick, but it seems to be something else.

[cjd]

Unless the rest of your setup is the same, it's going to be tough to have any other experience tell you that your car would be fine on stock sways...

I was stock but added a Strano front swaybar earlier this year and it's a huge help. 10k/12k f/r spring rates...

[Blue Gt]

SMG I have the Strano bar on the front of my FR-S with Tein Coilovers and Whiteline end links. I had to flip the bottom stud around on the end link so it enters the sway bar eyelet from the inside to prevent clunking at full steering lock. Not sure if the clunking noise I had is the same as your popping noise? DP

[smg1138]

I forgot to mention the popping sounds only happen when I turn the wheel. I mostly notice it when pulling out of a parking spot or just turning the wheel when not moving. Put the car up on a lift last night to torque everything down and make sure the sway bar was centered. The noise went away for a while, but came back today after driving a bit. It's not a major deal, but pretty annoying since it's my daily driver.