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Tracking / Autocross / HPDE / Drifting What these cars were built for!


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Old 09-26-2022, 08:10 AM   #855
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I like to run mine at 34F 36R. Think I started at 36 since that's what the car recommends in the door jam and wanted a little more out of the front in sweepers, so dropped the front a couple of psi, and decided that was enough sidewall rollover for local events. At ZMAX I'll drop it down 2 psi since that's a sealed pavement and drives differently from everywhere else I go.
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Old 09-26-2022, 08:14 AM   #856
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Had a blast yesterday, this might have been the deepest I've gotten into third at an event. Was great fun keeping it held coming into the final turnaround. I don't run data, but I'd guess I was somewhere up around 70 mph. Conned away a 4 tenths faster run keeping it pinned into that section for longer which would have put me 2nd or 3rd PAX, but ended up 6th PAX of 95 or so.

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Old 09-26-2022, 09:38 AM   #857
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Originally Posted by strat61caster View Post
Triangles are irrelevant to finding the best pressure, glad you figured it out.
I understand the triangles simply indicate where to find the wear beads in the tread, but since they are usually stamped right on the edge of the tread block aren't they at least one data point to consider?

What I mean by that is, while they shouldn't be used exclusively to figure out tire pressure, can't you use them to see if you're running too low? If the tire is rolling past them and onto the side wall, I'd think that would be a problem.

Adjusting tire pressure to optimize what little can be adjusted on a bone stock car is something I'm still learning.
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Old 09-26-2022, 01:51 PM   #858
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Originally Posted by Desertnate View Post
I understand the triangles simply indicate where to find the wear beads in the tread, but since they are usually stamped right on the edge of the tread block aren't they at least one data point to consider?

What I mean by that is, while they shouldn't be used exclusively to figure out tire pressure, can't you use them to see if you're running too low? If the tire is rolling past them and onto the side wall, I'd think that would be a problem.

Adjusting tire pressure to optimize what little can be adjusted on a bone stock car is something I'm still learning.
I go by feel and the clock for pressures, visual inspection and pyrometer readings have lead me astray before when it comes to autocross. Wear patterns and the clock/feel for alignment settings.
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Old 10-17-2022, 02:05 PM   #859
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Bummer it totally botched my season. It never crossed my mind to go higher because why would you raise pressures if yours understeering up front and they're right on the triangles?
My first couple of years of AutoX I bought into what most people seemed to be saying: "Set your pressures as LOW as possible without rolling over onto the sidewall."

After struggling in a similar manner as you, I did some research and learned something that even some fast AutoX'ers don't seem to understand. The best way to get grip is to ADD pressure. You want to set them as HIGH as possible, up to the point right before the tire starts to cup.

For me, this year, on the '22 BRZ in DS with 660s, that has turned out to be 35/35.

Slightly off topic...my understanding on the '22 BRZ...the rear camber is non-adjustable, and so is the rear toe. Is that correct?

Thanks,
Mike
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Old 10-17-2022, 02:19 PM   #860
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Alignment adjustments are identical to first gen. Front end has camber/toe adjustment and rear end has toe adjustment.


Also, the RT660 was designed around ~35 PSI as the target hot pressure. Not surprised that's where you ended up.
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Old 10-17-2022, 02:27 PM   #861
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I'm just not seeing how to adjust the rear. The tie rod is not adjustable, unlike the front.

Also, one other question while I'm here...does anyone have a link to the Koni shocks people have been using?

Thanks!
Mike
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Old 10-17-2022, 02:35 PM   #862
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Originally Posted by HawkeyeMike View Post
My first couple of years of AutoX I bought into what most people seemed to be saying: "Set your pressures as LOW as possible without rolling over onto the sidewall."

After struggling in a similar manner as you, I did some research and learned something that even some fast AutoX'ers don't seem to understand. The best way to get grip is to ADD pressure. You want to set them as HIGH as possible, up to the point right before the tire starts to cup.
Kinda curious about the basis of this.
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Old 10-17-2022, 02:38 PM   #863
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Originally Posted by HawkeyeMike View Post
I'm just not seeing how to adjust the rear. The tie rod is not adjustable, unlike the front.

Also, one other question while I'm here...does anyone have a link to the Koni shocks people have been using?

Thanks!
Mike
Just an eccentric on the inner end of the toe link.
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Old 10-17-2022, 02:41 PM   #864
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Just an eccentric on the inner end of the toe link.
Perfect - thanks!
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Old 10-17-2022, 02:42 PM   #865
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Originally Posted by DocWalt View Post
Also, the RT660 was designed around ~35 PSI as the target hot pressure. Not surprised that's where you ended up.

But wouldn't that be highly dependent on the weight of the car and drivetrain (FWD, RWD, AWD)?

Also a random update: Just did possibly my final event for the year. 660's got me through to 201 runs and still have tread left. The 200 runs were from co-driving a few events - total events for the year were 24 for myself and about 160 of those runs.
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Old 10-17-2022, 03:14 PM   #866
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Originally Posted by steverife View Post
Kinda curious about the basis of this.
Here are a few links:

Tirerack says, for example, to DECREASE understeer, INCREASE front pressure.
https://www.tirerack.com/tires/tiret....jsp?techid=58

This one is OK, a bit simplistic, but correctly also recognizes that there are many complex factors at play...
https://flowracers.com/blog/how-to-s...ng-track-days/

Another example:
https://www.yourdatadriven.com/how-t...yre-pressures/


I think the best article on this is here (but it is a very dry read):
http://farnorthracing.com/autocross_secrets12.html
I'll quote this article: "A tire will gain grip with increasing tire pressure until the internal pressure overcomes the strength of the carcass portions that keep the tire cylindrical, at which point the tire will start losing grip;"

Cheers!
Mike
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Old 10-17-2022, 04:23 PM   #867
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Originally Posted by HawkeyeMike View Post
My first couple of years of AutoX I bought into what most people seemed to be saying: "Set your pressures as LOW as possible without rolling over onto the sidewall."

After struggling in a similar manner as you, I did some research and learned something that even some fast AutoX'ers don't seem to understand. The best way to get grip is to ADD pressure. You want to set them as HIGH as possible, up to the point right before the tire starts to cup.

For me, this year, on the '22 BRZ in DS with 660s, that has turned out to be 35/35.

Slightly off topic...my understanding on the '22 BRZ...the rear camber is non-adjustable, and so is the rear toe. Is that correct?

Thanks,
Mike
I used a pyrometer to get to my base pressures and found 29/28 worked the best but YMMV
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Old 10-17-2022, 04:29 PM   #868
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I used a pyrometer to get to my base pressures and found 29/28 worked the best but YMMV
Just for fun, one day at the end of the event, or during fun runs if your region does them...try cranking it up to 35/35 for a run after running all day at the lower pressures. I'd be interested in your feedback!

Mike
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