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Hi Bob,

Two thoughts after reading that:

1. The increased "point-and-shoot" confidence with the new, very stiff front bar comes from a faster steering transient response.
2. "No understeer" is highly doubtful. It's incredibly easy to imagine faster transient response means less understeer. I hope you continue to look for that large patch of asphalt to do the test I described. Heavy understeer (or oversteer for that matter) reduces total lateral grip, so it's not the fastest way around a corner. But with a front-heavy RWD car, it's the compromise you're forced to make to keep both rear wheels planted in turns and with throttle/brakes.

I hope I'm not being too repetitive, and not that it helps at this point, but the real solution is to improve the car's miserable weight distribution first. Then, and only then, tweak the F/R roll stiffness balance. But you already knew that. With an ICE planted between the front wheels, good F/R weight balance simply isn't going to happen in an A/G body.

To add insult to injury, the more power why try to get out of the drivetrain, the heavier the front of the car gets almost invariably. Exactly the wrong recipe. GM hit the same brick wall with all the front-engine Corvettes through C7, and that's why the C8 finally became rear-engine.

Best,
MAP

Last edited by MAP; 11/14/22 12:36 AM.
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Just to follow up, the possibilities aren't quite that stark. A few thousand posts ago somewhere, I mentioned that front heaviness, plus high roll stiffness in the front and low roll stiffness in the rear, doesn't have to mean understeer.

Just look at the rear-heavy C8 and flip it around: use super-wide tires in the front, and narrower tires in the rear. (OK - so that will go over like a lead balloon.)

Or, we can increase tire slip angle at the rear by using tires there with a tall, soft sidewall. Besides reduced understeer, two results: First, it probably means larger-diameter tires on the rear, aiding the "hotrod" rake. Check, for most traditional hotrodders. Second, it helps decouple the high mass of the rear from the contact patches as a very high RCH rear tries to handle difference-mode bumps. Check, check.

I also mentioned that this could be easily explored by making a big reduction in rear air pressure. Check, check, check.

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One of the great methods to determine a suspension's geometry and setup effectiveness is to view how the tires wear.

These are the Nankangs I just took off my car with roughly 1,000 miles, 10 events (2 with a co-driver) and approximately 100 hard autocross runs on them. They were never rotated, as you see them is how they lived on the car the whole time.

[Linked Image from photos.smugmug.com]

I'm super impressed with how evenly they all wore. I could possibly go up a few #s in tire pressure to even wear even more but I think that would hurt overall footprint and grip.

This just backs up what I feel behind the wheel, a very neutral balanced car getting the most grip it can out of the front and the rear tires.


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Define neutral

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That’s cool you’re impressed, congrats Lance.

Last edited by 1 Slow SS; 11/16/22 10:25 PM.

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Originally Posted by MAP
Define neutral

If a setup creates an "understeer" outcome, the front tires would be sliding more than the rear, and the front tire wear would indicate such.

If a setup creates an "oversteer" outcome, the rear tires would slide more than the front, and the rear tire wear would indicate such.

The way I drive creates hopefully just the right amount of slip angle, front and rear. If I'm too aggressive I can make either end slide more than is desired and if I'm too conservative, neither end will slide.

My definition of "neutral" means my car's oversteer and understeer characteristics are pretty well balanced and the driver can influence either or neither to show up on course.


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Wow, those are some slightly worn Nankangs
https://g2perf.com/products/copy-of-nankang-ar-1-100tw-tire

Compared them to the RT660 sitting behind me right now, winter storage, with 60 runs and about 2K miles, the Falken's easily have another season left on them. Do you think the Nankangs is truely a 200 tire? i know you abuse them but would think if they truely are a 200 tire they wouldn't get ate up so quickly.
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There is no way neither the Nankang nor the 660 is a 200 tw tire. Frankly I'd bet they are less than 100 tw.


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Isn't that always a controversy among the serious autoxer's. "Is that really a 200 wear tire?" What usually happens is everyone is allowed to run that new tire so no one complains.
I really can't complain about the 660, surprised at how well they look and how even the wear is. Think that is mostly cause I rotate, a lot. And they didn't make the 600 mile trip to UMI last year or either Carlisle the car attended. That was 1000 miles of wear they didn't get, the old Comps made those trips.

I've been looking to see what the next set of 17" tires will be. Won't be a 200, not enough events, getting to old, to warrant a 200. Thinking may go with Continental, Pirelli in a high perf all season. Not because of the need to drive in bad weather but to be able to use the same tire for 12 months and also just in case you get stuck driving at 70 mph in a down pour. The RT660 may have been OK if the black top was just wet, but I'd hate to get caught in a downpour with them.
Bob

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I just drove up to QT on the 660s to fill up the tank, they are SO much stiffer than the new fresh Kangs...

Hopefully I can soften these rocks up this weekend beating on them at GGS.


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Cornfuzed.
That set of tires pictured is your first set of kangs?
The old 660 are on the car now and mounted on the old wheels.
A new set, second set of kang,,are on the Forgeline.
So it would be that set, new kang and forgeline going to GGS?
Bob
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More than steering balance is at play regarding tire wear rate. The implication you seem to be making is that equal wear means neutral steering balance.

Understeer and oversteer are functions of many factors, including longitudinal acceleration. I delved into that earlier in this thread. Depending on whether the car is seeing throttle, braking, or coasting in a turn, the longitudinal acceleration can cause the car to understeer, drive neutrally, or oversteer, with possibly all three occurring in the same turn. But the default interpretation of steering balance is with the car coasting or with very light throttle to maintain speed in a turn. This default behavior influences how the car reacts through throttle, braking, or coasting during a turn, shifting the car's average behavior toward one extreme or the other.

But once again, treadwear rate alone tells little about steering balance. Car weight balance, tire contact patch area, and heaviness of throttle and braking also strongly influence wear rate. It's not just tire slip angle. Oddly enough, through a balancing of throttle and braking, one could get the same wear pattern without turning at all.

To really know about steering balance, do the circling test I've described many times.

Last edited by MAP; 11/19/22 05:22 AM.
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Or, I could just not try to discuss "terminology" with an engineer... laugh

You'd think I'd learn after all these years.

Falkens on the Rockets rubbed inner fenders up front hard enough I couldn't steer the car as needed so after 2 attempts I bolted the new Kangs on and promptly picked up 3 seconds. Only got 4 runs total yesterday and maybe just 2 more this morning. I need to be in top 8 in SM to make the shootout this afternoon.

https://www.goodguysautocross.com/SM.php

Overall results

https://www.goodguysautocross.com/RawDay1.html


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That's a real stout group of drivers there, many pros. Right on the cut line, Barney has no reason to hang it's head.

Good luck in the afternoon.
keep me posted.
Bob

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This is funny as hell, thanks guys.


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I had posted in-between posts 1075676 and 1075678, but I hadn't seen all the previous posts when I did. (The same was true when I made post 1075672.) So I deleted it to review the full conversation first.

Thanks, Lance for defining neutrality. My last post actually anticipated such a definition and my reply was appropriate. There's a lot more to even wear than neutral (average implied) steering balance. I challenge you to do the understeer/oversteer test I defined to remove all doubt.

Last edited by MAP; 11/19/22 10:19 PM.
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Originally Posted by mmc427ss
That's a real stout group of drivers there, many pros. Right on the cut line, Barney has no reason to hang it's head.

Good luck in the afternoon.
keep me posted.
Bob


I was in decent shape in 7th this morning, then on Chris Halls last run he picked up a ton and bumped me down to 8th. That would have got me in on time but a guy further down the chart already had an invite so I missed the cut.

Still had a blast, love seeing all my friends from all across the Country at this event.

Only put 5 runs on the Kangs there so hopefully didn't age them out too much.


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In the morning session I noticed you had an affection for cones. You cleaned that up in the afternoon. From what I've seen of the GG courses they seem all the same, up, and back, up, and back all pretty much 180s. They are a little challenging because you need to find the shortest way around and unfortunately there are cones in the way. Sorry to see you get the boot by one car.
Is the Shoot Out tomorrow or did they run that already.

Is that Sean driving the TA. Is he still running his truck?

Many of those Pro types I've seen at KOTM. Hard to compete with the money they throw at cars, besides all being very good driver's.

So you are on your second set of Kangs?
Bob

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I couldn't turn the car correctly with the Rockets because the tires kept getting hung up on the inner fenders...hence the cones.

Things got instantly better after lunch when I bolted the new Kangs back on.

This course was a bit different, had one huge sweeper and then three sharp pin turns in a row before the finish. I'll get some videos up in a day or two.


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Sean was driving David Carroll's twin turbo chev blazer that just won an Oprina event.

Shootouts were all today, I stayed to watch them then kept about 2:30.


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Lance
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I would comment that the past several posts belong in "SSLance's Build Thread," in which I'm careful not to post. But naturally, that's your call, Bob.

I think this bears repeating:

Quote
Two thoughts after reading that:

1. The increased "point-and-shoot" confidence with the new, very stiff front bar comes from a faster steering transient response.
2. "No understeer" is highly doubtful. It's incredibly easy to imagine faster transient response means less understeer. I hope you continue to look for that large patch of asphalt to do the test I described. Heavy understeer (or oversteer for that matter) reduces total lateral grip, so it's not the fastest way around a corner. But with a front-heavy RWD car, it's the compromise you're forced to make to keep both rear wheels planted in turns and with throttle/brakes.

I hope I'm not being too repetitive, and not that it helps at this point, but the real solution is to improve the car's miserable weight distribution first. Then, and only then, tweak the F/R roll stiffness balance. But you already knew that. With an ICE planted between the front wheels, good F/R weight balance simply isn't going to happen in an A/G body.

To add insult to injury, the more power we try to get out of the drivetrain, the heavier the front of the car gets almost invariably. Exactly the wrong recipe. GM hit the same brick wall with all the front-engine Corvettes through C7, and that's why the C8 finally became rear-engine.

But to be clear, this isn't to fault what you and Lance did with your sway bars. Making the weight distribution correction is a Herculean proposition. Electric is the most feasible Herculean step forward. Short of that, you probably did the best you could, but there's still performance left on the table if you don't take steps to reduce understeer. (It's probably fair to say that unless the average exit speed of a turn is higher than its entry speed, understeer will hurt rather than help.)

I'm saying this for the benefit of others reading here. Bob, you already know all this.

Last edited by MAP; 11/20/22 11:48 PM.
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