GTB/ZR-1

Back into the fray (had a '15 Z51 previously in SS) with my new (to me) '16 Z51. 3LT M7 w/ Comp seats.

The car is completely stock, other than base 18/19" rims & a 265/305 Bridgestone RE-71Rs. This time around, I went w/ a good bit more front camber (-3) & -1.5 rear. It's lowered on stock bolts & corner-weighted (perfect 50/50 w/me in it).

This car also has Mag Ride, so first time experimenting w/ this (other car had standard Z51 suspension).

Maiden event w/ it was yesterday. The lot we run on is small and has terrible grip--almost like it's damp, compared to regular asphalt. It was also cold (for FL) & I didn't have a co-driver, so not a good barometer yet.

I lost by 1/10th to a very well-driven AWD 911 C4S (AWD cars rule on this lot due to their acceleration grip). My car was the fastest rear-wheel drive car there & also 3rd in PAX out of 102 cars.

Had the latest iteration STR Miata the past year. FANTASTIC AutoX car & won me a big championship in '17, BUT...

SO psyched to be back in a C7--and WHAT a difference from the Miata lol.

Some pics & vid:

Me in the car (~1/8th tank), and lighter Forgeline rim street setup--add 14 lbs for the AutoX setup:

[url=https://flic.kr/p/DRkoJM]
[url=https://flic.kr/p/22qzTef]
[url=https://flic.kr/p/23vfx2Z]

The latest base rims clear the Z51 brakes:

[url=https://flic.kr/p/DRk9uK]

Vid (my passenger enjoyed the ride lol):

GTB/ZR-1

HOLY Hot Front Rotor, Batman! lol

daleong

WoW!! Terrific picture

08velocity

I see you are in Winter Garden, we are in 4 corners, 27/192 area, where was this small autoX at ??

GTB/ZR-1

Not too far from you in the Tavares/Astatula are off 561.


Check out info on our club:

martinsportscarclub.net

08velocity

Awsome, a couple of our friends live literally out in your area !!! They have silver c6, and recently just got this 17GS

Takoyaki

Great job. Jealous that Z51 has a good choice on tires. Z06/GS has nothing.

What drive mode did you drive with?

GTB/ZR-1

Well, I go to track track mode, turn everything off (can't do that starting off in sport mode), then twist back to sport mode. I did that because I believe the Mag ride in sport will be more compliant than track. The surface of that lot needs a softer setup to have any hope of maintaining traction out there. I'm sure I'll run it in track mode on a better surface.

Speaking of tire choice; when I first got me '15 C7 in early '15, I ran a 245/275 setup. The 265/305s setup is MUCH better lol.

I just wish the base C7 had at least stock 9.5/10.5" wheel-widths. The 8.5" fronts especially, leave a lot to be desired to run in Street.

daleong

Wow, first time I've seen a Z06/GS owner jealous of a Z51!!

Takoyaki

True You don't know how much time I've spent figuring out different tire combination and ended up with the stock Cup 2 tires which costs 50% more and lasts 50% of RE71R.

rplanddeck

formula80_ca

If you are running under SCCA rules in A Street class you can't vary the width of your rims at all, not even .5" and remain in Street class. You can vary the diameter up or down by 1".

Good luck

formula80_ca

Good luck with the new Vette this year!

I had a great year last year in A Street with almost the same setup as you. By mid year last year I was getting some firsts or usually second overall in Pax out of up to 140 competitors. If a certain well setup and well driven Mustang GT was there it was second. He's a great driver and F Street Pax is so much softer i would have to beat him by around a second in raw time. He beat me out in both the Street championship and the Overall championship but still had a great year.

I have the 8 spd paddle shift auto instead of your manual 7spd and was one size wider in tire at 275 RE71s on the front. I was at -2.5 camber on front and 1.9 rear. I found that at -2.5 the inside of the fronts were often hotter than the outside. Have you monitored that yet? Also, have you decided that 265 on front is supported better on the 8.5" rim and therefore it gives you better grip than stuffing a 275 on?

Note: The new base wheels do clear the Z51 rotors but only just on the front... so for anyone going to this setup keep in mind that the balance weight placement on the outside of the rim is critical or they will hit the rotor.

rplanddeck

After posting I wondered if anyone would catch that. I normally autocross in National Council of Corvette Club events which allow + - one inch in both diameter and width. Since my post I have decided to stick with SCCA rules so I can do both.
But thanks, could have saved me an expensive mistake.

GTB/ZR-1

Wow--nice job! That's great work w/ the A8, since it only tops out around 64 in 2nd, as opposed to 72 w/the M7.

I figured the 265 would be as far as I should go w/ the 8.5" rim. I'm trying -3 & am monitoring how it works--need more events to tell.

Good luck this upcoming season--although I'm thinking your months away from starting--because... Canada! lol (I'm originally from upstate NY, just off Lake Ontario--so I understand ;-)

rplanddeck- we have a good group of people w/ an NCCC club in the area. I need to reconnect w/ them. I think my car would be a very strong 1A (?) car. Have fun!

Bill Dearborn

Once I move back out of track mode I lose anything set up in track mode. Although I am only familiar with pushing the button twice and going to the sub modes, Wet, Dry, Sport 1, Sport 2 and Race. The only autocross I did in my Z06 I used Sport 1 which gave me great runs as I was able to garner FTD at an NCCC autocross.

In Sport 1 I had PTM working coming off the corners and I could really go hard on the throttle as I came off the apex. I could hear PTM modulating the power to the rear wheels to keep them from spinning too much. Don't know if PTM will work for you in your autocrosses but it might be worth a shot to see if it could help.

Bill

rplanddeck

Trivia...Just had an opportunity to weigh stock 19/20" Z-51wheels:
Black: F 24.4 lbs. Rear 27.5 lbs.
Chrome: F 27.5 lbs. Rear 29.8 lbs.
Any idea what the wheel weights will be with stock 18/19' wheels?

formula80_ca

I was pulling 3rd gear at atleast one point in about half of our events last year. There is less lost time when shifting with paddleshift so not as bad as with manual.

Being above the 49th parallel does mean some cold in the winter but the west coast is much milder than anywhere else in Canada. Much more rain than snow. So we actually start up the regular season in late March and go until mid to late October. We also have a "slush" series that goes through the winter but the Vette is not great in rain and cold temps so I rarely participate in those. The 4 wheel drive guys rule that series.

Good luck in the rest of your season and report back on how your camber testing goes.

Cheers,
Clive

rplanddeck

GTB/ZR-1 Awesome car! Current NCCC rules put ZR-1 in 1SN (Group "'1" for stock car/no mods, "S" for street tires over 140 tread-wear and "N" for performance class. With Hoosiers, leave the "S" off. With mods, class moves to Group 2, "2N". Have fun!
The nice thing about NCCC AX is that there are usually 4+ Corvettes in most classes which makes it fun.
Bob

itch808

Any trouble with mounting those tires on the stock wheel widths? With front 8.5 and rear 10, it looks to be 1/2" short of min recommended wheel width for those tire widths.