turbo8765

I'm looking for feedback on something that is admittedly largely subjective.

What's the balance like for a C7 Z51 with a non-staggered setup vs the stock PSS w/ 40mm stagger? Obviously it will have less understeer, just trying to get a better idea wha the non-staggered setup is like. On an otherwise car is it too loose? Are most track guys running a non-staggered setup on the C7?

If anyone has data for an objective comparison that would be awesome.

GTB/ZR-1

Your thoughts are accurate. The car will be a handful when driven at/near the limits. It was designed with a 40mm stagger & will be most stable with that split.

I'm running a 245/275 combo for my stock SCCA setup & even 10mm less & a bit too much rear pressure & the car was loose. To the point where it instantly let go at an event. Granted all the nannies were off, but that's the true dynamic. I'll post the vid later for a good laugh lol.

turbo8765

Thanks for the feedback.

Loose on turn in? Mid turn? Or primarily with throttle?

GTB/ZR-1

Good question--mid & exit.

GTB/ZR-1

NTMD8R

You are on (obviously) old concrete... it pretty much holds better than asphalt.
You were "done" when you started that last turn... too fast on entry.
I presume this was the "turn around" (180 degrees) to start back?
So you took this turn at the same or greater speed you took all the other curves.
I wouldn't necessarily blame the tires or pressure.
Based on what I saw, I think your were just too hot for this 180 degree turn.
But, yes, the back end came out (oversteer).... so a bit less tire pressure
in the rear might have made some difference... but I doubt it.
"In Slow; Out Fast" for a turn (not so much in mere "curves").

Still, nothing got broke or busted, so all is good.

I always instruct my students to "finish the run"... to at least get some more experience
with the course layout.

GTB/ZR-1

Um... I'm not exactly a newbie @ this--and you don't know who I am--but I won't bore you w/ my qualifications lol

It wasn't the turnaround. The NCCC guys that set up insane courses w/ heavy offsets @ that venue. My car was within .5 of a SSM C5 Vette on full slicks--my car is stock.

This is what it looks like when done right:

EvilBoffin

George -

You mentioned at the end of your video that you think you still need more rear toe-in . . .

If you don't mind sharing - how much do you have currently, and how much do you now estimate you really need??

GTB/ZR-1

Approx 1/8th" total & think it could really benefit @ 1/2"--although that would kill the tires on the street.

EvilBoffin

Wow - its disappointing to hear that the C7 is yet another Vette generation that needs that much rear toe-in to work well.

I was hoping to avoid that, because I have that much or more on my C6 GS now. Though it works REALLY well, I have to change the toe back n' forth between 'autocross' and 'street' settings each time, to preserve any semblance of tire life.

Is it safe to assume that the skinny 275 RE-71R's you're using in the back are part of the problem???
Maybe, whenever tire companies bother to make them for USA markets, we can get wider rear tires for 'Street' class that will improve this rear-grip situation, and less toe-in will be needed to put the power down consistently.

GTB/ZR-1

Robert-

I'm hopeful the reduced stagger is the issue. I've not driven the car in anger w/ the OEM PSSs (keeping them nice). I'd love to try a 265/305 combo in some of the new 'S-comps', (bet the C7 would run w/ anything is SS w/ those sizes) but the 245/275 sizes were the best compromise I could find. The primary issue/drawback is there's nothing wider than 275/19s (or 20s) in the new-generation tires.

That being said, I do think a 30mm stagger would work--with rear tires that are beefy enough.

I'm going to try 1/4" total-toe next, in hopes that'll be a good compromise...

OP- I hope we're staying on-topic enough for the thread ;-)

baron95

I too would love to run square. I always like to take an extra mounted tire/wheel to the track in case of a flat. (On my last track day, I actually ran 4 session with a large screw in the front tire - I screwed it in more and it held pressure, but if it hadn't my day would have been ruined).

After doing 6 track days on my C51 with the OEM tires, I love the car balance. It has a hint of understeer if you overcook the entry, and just the right amount of oversteer when you push the power in. So the car is properly tired from the handling standpoint.

But while the the fronts were basically worn - could at most to another 1/2 track day -, the rears still had another 2 or 1 and 1/2 track days of life.

I just got them all replaced, but I think going forward I'll end up running 3 front sets for each 2 rear sets. A fresh set in front and worn rears will be more of a handful, I think.