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Old 10-22-2019, 12:35 PM   #153
rennlistuser3
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For those interested in getting a very detailed insight on the C8 stingray handling characteristics, I found this Corvette thread

https://www.corvetteforum.com/forums...ck-review.html

It's a pretty big one, but it's super insightful to see how the hardcore FR old school Vette guys go up against this new MR C8.

My personal takeaway message from that thread is that the C8 stingray suffers understeer and to fix this problem Chevy reduced the rear end grip to make this into moderate understeer. But it is not mild understeer or neutral or oversteer in character and therefore unacceptable for me. Moderate understeer or more understeer are a big no no for me in a "sports car" or GT or whatever you wanna call it. Also this problem cannot be fixed with alignment or fatter front tires. The Chevy engineers are struggling with this problem and hope to solve it in future models. For me the C8 Stingray is a pass. I'll wait to see if this issue is solved with the Z06/GS else it's a no for me.

The most interesting part I read on that thread is personal write up by Jason Cammisa on comparing the C8 with the C7. It was taken from another thread but I found it on this thread. I'm quoting it here because it's the most interesting I read:

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Originally posted by JasonCammisa View Post
Hey guys. Okay, to answer the first question: I had two sessions on track with the C8, one was 7 laps at he end of a fairly long morning of abuse; the second was 7 laps on a new set of tires. When I hopped in the car the first time, it was in Track + PTM 5. I left it there. Toward the end of the second session, I turned ESC off fully.

As a matter of course, I test cars with their ESC systems both on and off. For cars with advanced track modes (like the Corvette) what I'm looking for is to learn what, if any, bad habits the system is trying to cover up.

Some Ferraris, for example, are amazing in Race Mode; neutral and predictable, and they feel 100% natural. It's only once you switch everything off that you realize the car is inherently very unstable at the rear, and the computer is managing everything. It's that well integrated that you mostly can't feel it working.

Even PTM 5 (on any GM, not just the C8) isn't really like that. It leaves you alone to do whatever you want, but will step in only to save your bacon if you're really about to lose it. In the case of the C8, I didn't feel a single intervention on track until I booted it gracelessly coming out of a hairpin to induce a slide. All it did was cut power (a TC function, not an ESP function.)

The car's behavior in the two modes was the same: easy to manage, incredibly stable, and very fast. My first impression was that it didn't have the oh-my-god levels of lateral grip that the C7 had at launch. The skidpad number (1.03g vs 1.08g) bear that out, so my butt-calibration wasn't off.

Understeer is an oft-misunderstood thing. Cars that don't understeer at all are uncontrollable — think of a shopping cart with omnidirectional casters at the rear. The fastest — and incidentally most rewarding — setup is that of very mild understeer to neutral. Basically, you want both ends of the car to reach their limit at the same time. If anything, maybe the front a hair before the rear.

This is mild understeer. And if the limits of the two axles are very close, you then have the ability to manage them using throttle, brake, or steering inputs. A mid-engie mild-understeerer can be made to go neutral with a small amount of trail-braking, for example.

The reason we (and C/D, and MT, and everyone else who's driven the car) complained about the understeer is for a few reasons. Firstly, it's not mild understeer: it's moderate and then some. This means, as a driver, the repertoire of tricks you have at your disposal to change the car's mid-corner attitude are very limited.

And by the way, when I say "we," I'm not talking about "me at Road & Track." I'm talking about the combined editorial staff. I'm sure you don't need or want a speech about the way magazines work, but when I'm writing a piece about a car as important as the C8, you can be sure I shared that story with my colleagues to ensure that we all agreed on those words. The senior R&T staff saw, and edited, that piece to make sure we all agreed with every word.

I should say that two other experienced drivers on staff didn't feel that the C8's understeer was an issue; they found ways of driving around it. They said they were able to get the car to rotate using big steering inputs, brake stabs, and massive trail-braking.

You've probably all seen my stunt driving — I've done literally thousands of huge slides for the MT videos (and everything else I've done) — but I was NOT going to risk crashing a C8 prototype for the glory of getting the car to rotate. Frankly, the whole point of a mid-engine car is that its low polar moment of inertia eliminates the need for that kind of driving. I got it sideways only under full throttle in 2nd gear on corner exit — and it was progressive and easily controllable. But since those guys found ways to drive around the C8's handling limitation, that line made it into "my" piece in R&T.

Fact is, I can get a Camry to oversteer — and quite easily — using those same moves. It shouldn't be necessary in any sports car. And definitely not in a Corvette.

I mean it when I say that GM does some of the best chassis tuning in the business. They have a secret sauce on the C7 and Alpha-plaform vehicles that somehow gives steering response at the understeer limit. This violates the laws of physics — you can get those cars to go neutral even after they've started understeering, using the steering alone. It's likely a combination of MR dampers, diff, and really good elastokinematics. The cars are unbelievable. They're some of the most rewarding limit-handling cars ever made.

The C8 doesn't do this.

I'm not in the business of getting hard-working people fired, so there will be no names ever given. Put it this way: GM confirmed to me the limit-handling magic trick that the Alpha/C7 cars do isn't possible on the C8 for engineering reasons. But they're working on it. I suspect subsequent versions of the C8 will do this trick... but the Stingray will remain a resolute understeerer for production.

Let's talk about understeer. Does that mean that the C8 is less rewarding on a track for an advanced driver than it could/should be? Yes. Does it mean it should/could be faster around a track? Absolutely.

Does any of that make it a bad car — or a bad Corvette? Of course not. It's one data point!

You guys are clearly enthused about the car, and nobody wants to hear bad things about something they're excited about. I get that — but please, let's keep the conspiracy theories under control. There's no plan to sell additional magazines. I don't want, need, or care to re-spark a career that's not dead. (By the way, I didn't suddenly reappear at R&T; I've been working with those guys since Travis took over 6 months ago. I have a tech column in every issue.)

And as for "perspective:" the thing is fast as (insert profanity here.) Beats every Corvette ever tested to 60 mph; nearly ties the C7 Z06/Z07pkg through the quarter mile. That's a huge achievement, especially given no substantive power bump over the C7 Stingray. I wrote a big tech piece for R&T's Performance Car of the Year issue on that, explaining how it's possible. It's simple physics, and GM's intelligent guys and gals took advantage of the physics benefits of MR traction and a quick-shifting DCT. They did good.

The rest of the car is pretty dang good, too. I seriously cannot express how well it rides — it genuinely redefines what a sports car can ride like. Feels like you're floating on top of the pavement; it's a strange experience. Is that what a Corvette buyer wants? I'll leave that for you to decide. Doesn't matter what I think.

It doesn't matter whether like any part of the C8. I get paid to tell you about the facts, not the opinions. Facts are: the C8 will beat every other Corvette ever made to 60 mph. It rides like a dream. The passenger-side space is compromised because of the buttons. C7 had better steering feel. Brake-by-wire's didn't please everyone. Transmission has some programming issues that I expect will be taken care of before production begins; but its shifts (go see my IG acceleration video for an example) are nowhere near as quick as PDK's, etc. And the car has far more rear-axle grip than front grip in corners, meaning it understeers.

Any other facts you'd like to know? I'm happy to answer the questions. HeII, I'll give you my feelings too, if you want to know them.

Hope this helps!
Jason
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