Thank you team Corvette, my shop was able to get -2.9 degrees front and -2.5 degrees rear negative camber with no aftermarket parts. Turn in and grip are improved even on the street, and I can't wait to get her out on track. With my Porsche GT4, a similar alignment required camber plates, thrust arm bushings, front tie rods, rear toe links, toe link lock kit, and lower control arm shims. So nice to have the adjustability on the stock Z06 without all the parts and labor needed on the GT4 below!

 

That’s great. What tires will you be running? Any pics of the setup?

GM track prep says -2 F and R on Z06. Any reason you went more aggressive?

 

Was it easy enough for the shop to do? I am curious if any panels needs to be removed or if it’s reasonably straightforward…

 

I bet it feels great but Cup2 Rs are going to last about an hour.

 

Any moderately good driver will murder the outer edges of the tires with those settings. We're found that aggressive drivers will end up around -3.5 +/- a little front and -2.5 +/- a little rear.

 

Track wheels are custom 19 inch BC Forged monobloc forged aluminum wheels. Tires are Nankang CR-S v2 in 295/30/19 and 325/30/19. Interested to see how the combination works, but I didn't want to use stock size cup2r due to running costs. Wheel pic below, more pics from the track in a couple weeks.




I went with a more aggressive alignment to get better outside shoulder wear on track and grip. I am willing to trade some street driving tire wear to improve track performance and wear.




Fairly straightforward, took about 1.5 hours to tweak it and get it just right. Some of the undertray is better to remove for access.

Yeah, no doubt Cup2R won't last long. I'm running a 200 TW Nankang CR-S v2 to attempt to get more life on track. We will see how it goes!

Agreed, I target -3.0 front based on what I have used in the past on several cars but certainly slightly more has and will work well.

 

What’s the wheels size and offset? I am looking for a 19” set too…trying to see if I can use 3rs. Could also share the vendor who ordered the wheels for u? Thx

 

I did 19x10.5 front and 19x12 rear. I would love to use Goodyear 3R tires, but while I want to kill understeer, I didn't know if the available front sizes would work well (305F/325R would reduce the stagger from 70mm stock to only 20mm), and I wanted other tire options if and when there are tire supply issues which I have had in the past. I talked to some folks who ran 295/30/19 and 345/30/19 Hoosier R7s with good success, and the Nankangs I am using are similar in actual sizing. There are options in 295/325 including Goodyear SC3, Continental Extreme Contact Force, Nankang, R7 as well as other options like Toyo RRs, R7, and Conti ECF in 295/345 that will also fit.

For specific offsets and sizing, I would talk to Dan Young at BC Forged North America to discuss your desired setup. He was very helpful and I ordered direct from him and they were produced, milled, painted, and shipped in around 3 weeks. http://www.bcforged-na.com

 

Thank you very helpful

 

Rich,
Have you got any data on caster gain with compression? I know that increased caster gives better camber gain (negative outside/positive inside) in a turn. If the C8Z has significant caster gain with the nose down (under compression), then you will get better camber curves with the nose pinned down. That is the issue I am struggling with. Good aero front downforce or shocks with a lot of rebound resistance is the standard answer, but the C8, even with Z07, may be a little short there. Spring Mountain teaches trail braking to keep the nose down and make the car turn, but they couch it in terms of loading the front tires with no discussion of the caster/camber relationship. I am not a fan. Adding more static camber is a bit of a crutch since it can slightly hurt straight-ahead braking, especially with additional camber gain under hard braking, and adds the wrong camber (negative) to the inside tire in a turn. I plan to pull my front shocks and measure the caster gain (and resulting camber changes with turn) if I can't find published data. Since you can't reprogram the mag ride shocks, more aero upfront is the only partial, easy solution. I really hate to get into the soft springs and bump stops rabbit hole. If the increased caster gain measures as insignificant, then I will probably try just relying on slicks - I have had good luck with Yokohama 300/650 on 12" wheels up front and 330/710 rear on 13" wheels. The Yokohama is available in 19" sizes. It didn't take but a few laps in my 1LZ Z07 to figure out the Cup 2Rs needed more camber - one way or another.

 

Your tire/whl combo means your overall diameter (OD) in the rear is one inch lower than OEM, while your front OD is equal to OEM. I wonder if the electronics will intervene on the track?

 

Its not that far off from my measurements with the Nankang, but we will see what happens. OD is similar to Hoosier 295/345 combinations that have been used successfully by folks, but I won't know for sure until I try it out.

 

from what I hear - and those with a C7 could chime in - the C7 Z06 also has 1 inch stager but does fine with 18” front and rears on track (I.e non staggered). So hopefully the C8 is ok with it. I believe some folks here are using non staggered wheels already without issues.

mike - did you consider going with 19x12.5 in the rears? The 325s would fit on a max of 12.5 per specs for the tire…

thx

 

I considered 19x12 through 19x13 for the rear, but after talking to BC Forged we decided 19x12 was best for my desire to be able to run both 325 and 345 on the rear. After mounting my 325 Nankangs on the 19x12 I don't think I would want a wider wheel personally. Design widths and sizes are very similar for Nankang and Hoosier R7 in 325 and 345 respectively below.

 

Got it. The 3r specs for 325 on tire rack actually say rim size up to 12.5” hence I was considering that…

 

From owners i have talked to 19x12 to 19x13 works in the rear with proper offsets so you should be good if you want to go 19x12.5.

Picture of what set? The wheels and tires?

 

Not concerned about the smaller rear tire width?

 

The 325 Nankang is essentially the same width as a 345 Hooiser R7 when I compared them mounted. One of my goals was to kill understeer by reducing the factory 70mm stagger front to back (345R to 275F) by moving to 30mm stagger (325R to 295F). We will see how the balance is on track, but looking at both the front and rear Nankangs mounted I don't feel like I am lacking rubber contact... they are huge!

It's definitely a new combination I haven't seen run yet, I'm hoping it's balanced like the Hoosier R7 295/345 combination several folks have run. The actual sizes are very similar. Nankangs will obviously have less grip, while hopefully lasting significantly longer on track.

 

Just checking back to see if you have had a track day to try out the wheel/tire combo?

 

Did one track day so far, no issues with the nannies or ABS with the 295/30/19 front / 325/30/19 rear Nankang CR-S combination. I will say though that the stability control is really intrusive on track so in my opinion you have to use PTM Race 2 or full stability and traction control off.

The clearance between the 19 inch wheel barrels and calipers in the front is fine, in the back it is close so I clean the big rubber clag bits off a bit regularly more on the rear wheels. Car is fast even with me searching for good operating tire pressures and taking it easy my first time out with the car driving 6/10ths and on 200TW Nankang tires. Tire wear looks good across the tire with -3.0F/-2.5R camber, will see how long they last as I ramp up the pace but so far so good. First few sessions grip was sketchy, but as I lowered the hot pressures down to 30-31psi the Nankangs were much more happy and took the heat throughout the sessions much better.

Another side benefit of the shorter 325/30/19 rear tires is it improves overall gearing and acceleration is strong.