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Tracking / Autocross / HPDE / Drifting What these cars were built for! |
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10-11-2021, 10:59 PM | #43 | |||
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I've run even more ridiculous tire diameter stagger on my old S2000, 205/45-16 fronts with either 225/50-16 or 245/45-16 rears, and its ABS didn't have a conniption over it, just seemed to maybe have more front brake bias. That said, I'd probably stick with non-staggered tires, particularly diameter, I only ran non-staggered at NHMS due to fear of stripping the front right wheel studs so didn't want to change the fronts from the 245/40s that were on them. Last edited by ZDan; 10-12-2021 at 02:39 AM. |
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10-13-2021, 09:58 AM | #44 |
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That stagger would give ~7% difference in the lever arm for braking (tire radius). I wonder if that was enough to be noticeable as a change to braking bias.
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10-13-2021, 11:05 AM | #45 |
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10-20-2021, 10:38 AM | #46 |
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Dan how are your bushings looking?
I added the MCA traction mod to the rear of my car and I get a mid corner push now, which leads me to believe the rear is planting more, giving me more traction, allowing me to get on the gas more and sooner. Point is, maybe your bushings are worn enough to where they are changing the characteristics of your rear suspension??? |
10-20-2021, 12:08 PM | #47 | ||
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Prolly squished! FWIW the bias I mention above is/was braking bias with 7% shorter front tires on the S2000.
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10-21-2021, 09:09 AM | #48 |
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When you say mid corner push, are you at the apex and on throttle?
Yeah bushings are pita! |
11-16-2021, 08:25 PM | #49 |
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Super-late reply, I missed this! Car is just not as "pointable" as it could be. I'd like to trade some rear lateral grip for front lateral grip. I might try a softer front sway, I'm currently running Eibach tubulars set soft front and stiff rear but that's ~150% stiffer than stock both front and rear. Hmm, akshually I think I'll just try stock front with the Eibach rear and see how that works out next year... But I worry a bit about too much rear roll stiffness overwhelming the Torsen diff's ability to drive both rear wheels out of corners esp. over curbs...
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11-16-2021, 09:07 PM | #50 | |
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I was just looking at data from these laps and figured I'd post up, as it's an interesting look into how radically inconsistent my driving is from day to day. Explains a lot, actually! Tires are Yoko A052s, the 245/40-17s were barely used while the 235/45-17s had a few events on them.
Green: 2:14.283, Saturday best, 245/40-17 all around Brown: 2:14.370, Sunday practice 1, 245/40-17 front, 235/45-17 rear Purple: 2:14.769, Sunday practice 2, 245/40-17 all around Conclusions: At *this* track, the taller 235/45-17s had a gearing advantage. BUT The big takeaway is that for some reason on Saturday I was WAY better at getting out of the brakes in Turn 6 and Turn 9 and carried *massively* more speed from turn-in to apex. Why wasn't I doing that on Sunday?! Quote:
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11-16-2021, 10:38 PM | #51 | |
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This logic fails a simple mental experiment: Imagine a car with stiff springs, no rear bar, a stiff front bar, and appropriate alignment. Not an uncommon setup among spec Miatas. Now imagine you want to add overall roll stiffness, while keeping the overall balance. If you only increase the stiffness of the front bar, the balance will clearly become more pushy. Obviously, to keep the balance you'd need to increase the rear bar too, but since the baseline for the rear bar is zero, you'll need to increase it by "infinity"%. As a more practical example, I just opened the spreadsheet my friend uses to calculate suspension balance for BRZ/86s, took the row with parameters for a stock '17 PP BRZ, increased the front roll bar by +150%. Then I tried to find the % increase for the rear bar that would result in the same front vs rear roll balance as a stock. Turns out the rear bar needs to be +200%. Things are even more different if you use non-OEM spring rates. |
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11-16-2021, 10:46 PM | #52 |
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11-17-2021, 09:27 AM | #53 | |
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Thirdly: if you're going to propose this kind of mathematical problem you would already know that the formula doesn't apply as you approach either 0 or infinity. This neither proves nor disproves the formula for any particular range of numbers. |
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11-17-2021, 09:38 AM | #54 | |
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Based on Sunday's times I think you've proved that the reverse stagger works; maybe you just need to gain some confidence in its grip levels on corner entry to pick that speed back up. All of this is purely conjecture of course because I wasn't there and I'm by no means an advanced coach. |
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11-17-2021, 11:57 AM | #55 | |
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At NHMS I had a similar situation at turn 9 where I was carrying WAY more entry speed, but will have to check my data to see if the difference was Saturday to Sunday or Sunday Morning to Sunday Afternoon. I think I was pretty consistent throughout the weekend in 6. I'm gonna email yah. |
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11-17-2021, 02:18 PM | #56 | |||
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Ah, no worries.
Can you tell/remind me what spring rates you're running? Also, "150% stiffer than stock" — than which stock? '17 PP or '13-'16? Quote:
100 * (5 - 4) / 4 = 25. Now put 0 instead of 4 and you'll see that it's definitely not a 0% increase. Quote:
I know that springs also contribute to the overall stiffness, and mentioned springs twice in my post. Quote:
However, if you look at the "% increase" as a function of baseline bar stiffness, the limit of such function at 0+ approaches infinity. It's not uncommon for people to refer to this as simply "infinity". |
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