truth.b

Interesting, GS does mid to high 130's at the kink. Surprisingly I'm able to take it flat with street tires, I wonder if it is because I have magnetic ride. Maybe that 5-10 MPH really turns the kink into a turn?

Poor-sha

Bigger ***** Seriously, I don't doubt that the C6 Z06 can go flat through the kink - better drivers than I do it and I'm sure they're going faster. I just never felt comfortable doing it in the C6Z. That's really the thing for me in the C7Z is that it's confidence inspiring.

1badtantrum

To me, non pro, 5-6 events a year, the difference between 130 and 140+ through the kink is significant. I think it is definitely ball size, and risk comfort level. All influenced by car handling and feedback. I just checked 3 of my top 4 laps at VIR this past fall with the new aero described in above thread. I'm entering the kink about 140 and exiting about 150. last year without the aero and suspension changes, I was happy/comfortable with 130. I don't think that is foot flat. I rarely drive with my foot to the floor as far as I know. I haven't conquered the 2:00 barrier but I'm closing in, added aero is a huge part of this undertaking with the C6Z06.

neverstop

I've had my car >175mph at 1/2 mile events and it wasn't a huge deal but the lower my car is the better it feels, and just did trackspec hood vents which also made a noticable improvement in front end stability at speed while also helping air flow and cooling.

zrracer

I hope you guys that are lowering your cars are using rake and scales when you do it. I put my weight in salt in the drivers seat plus typical amount of gas and heated tire pressure. I also use frame height for rake not fender tops.

Jake5670

Travelor

I have had my bone stock 2012 GS coupe to 175 on a straight followed by a flat but large radius corner at 140. No lightness in either the straight or corner.

I think that a lot of the problems arise when the owners place larger rear spoilers on which causes more rear down force with no down force added to the front. I think Pfadt Racing Engineering had a chart one time on the C6 showing down forces and explaining the problems with added spoiler.

Just my experience.

c5racr1

Spring rates have a lot to do with it also.

c5racr1

Apr front splitter, 150ish on front straight



Home made plywood splitter 3 inches forward of the bumper cover, going rear ward to oil pan. 150ish on the front straight

c5racr1

I did go from gm t1 suspension to lg 700/750 coilovers

1badtantrum

c5racr1,
Those images say alot! Lots of downforce from that big wing, way out of balance with the front aero. Next image looks much more balanced.
700 front, 750 rear?
plywood splitter fiberglass wrapped?
How do you keep the plywood sealed to the bottom of the front fascia?
Radiator tiltied forward?

c5racr1

700 front 750 rear, oak plywood splitter, painted with a marine water proof paint. The plywood is sealed via a number of turn buckles mounted to various parts of the frame in the front, sling with the 2 splitter supports. In the rear it has some big zip ties at the pick up points where the stock leaf springs mounted. The radiator is in the stock position, have not leaned it forward yet. No cooling problems, but I run NASA time trials so at most 15 minute sessions.

c5racr1

Before paint

69427

It's pretty easy to visualize what happens when a large rear spoiler or wing is added. The spoiler or wing will obviously add more rear downforce, but this causes two things to happen. The first is that because the downforce is behind the rear axle centerline, the frame acts like a grade school seesaw/teeter-totter. When you add weight (or a force pointing downward) on one side it tries to lift the opposite side of the teeter-totter. In our case the opposite side is the weight that is trying to press down on the front wheels for traction. The upfront stuff/mass is still at the front of the car, trying to throw the car to the outside of the corner, but the downward force on the front tires is now reduced due to the teeter-totter effect, causing understeer. In addition to that understeer cause, there's also the "no free lunch in this world" rule. The rear spoiler/wing downforce comes with a penalty of drag. This drag vector/direction is straight backwards at the spoiler/wing height, which is 3 or 4 feet above the ground. This is identical to what happens when you use your shop hand truck to move a heavy item. You put your foot at the axle, and pull back on the handle up on top. Because the hand truck is a non-flexible item, when you pull back on the handle the load on the truck ahead of the axle necessarily has to rise up. Simple mechanics/leverage example.

Mordeth

On my 2007 Z06 I have a ZR1 style front splitter and just recently installed a splitter brace. ZR1 side skirts as well. Is this sufficient frontal down force to offset the down force created by a rear ring? Or will I be unbalanced? Have been considering an APR wing. Car is tracked.

davidfarmer

taking off the airdams under the nose will eliminate the pressure under the nose. They say those are for street economy, but they just create high pressure where you don't want it.

Mordeth

Thanks. I think I will remove the entire airdam this weekend. I need more front downforce.

FASTFATBOY

If the correct rake is in the car, I can't see this being an issue. My car is rock solid at 140mph with stock suspension (C5 Z06)

FASTFATBOY

That first pic, are you in 3rd gear? If so, 550whp in 3rd gear on slicks would tend to squat the rear.

c5racr1

If you look at my top picture, I had the exact setup you are going to. The rear wing set at zero angle of attack was too much for the apr stuff, I have side skirts also.