DansBlkonBlkZ06

I lowered by '02 Z06 last year and think I lowered the rear too much. The rear shocks felt like they were bottoming out at CMP a few weeks ago. I raised the rear today so that it is now 1/2" lower than stock, but now my rake is 3/4". I've read that 1/4" rake is stock, but is the 3/4" too much for the track? I would think the lower front would help keep the air from under the car. The front is lowered a little over an inch from stock. Thanks for any feedback.

rustyguns

i measure 1/2 inch from front to rear on the shipping holes in the frame
( jacking points ) seems to work well.

waddisme

This is from AU e engel:

Here is the SAE paper: http://www.sae.org/technical/papers/2002-01-3333

"Abstract:
This paper documents a one shift (10 hour) wind tunnel test program conducted on a Corvette C5 prepared for Sports Car Club of America (S.C.C.A.) World Challenge racing. The testing was conducted at the Canadian National Research Center in Ottawa, Canada. Specific areas of test included front fascia and under tray, rear air discharge, rear wing configuration and angle, B-pillar configuration, and ride height. Standard wind tunnel test procedures were followed. In total twenty-six separate configurations were evaluated. Data for front and rear lift, total drag, and lift/drag (L/D) ratio are provided for each test configuration. The cumulative effects of the aerodynamic changes evaluated in his program, calculated at 192 KPH (120 MPH), increased front down force by 318 N (72 Lb.), and rear down force by 770 N (173 Lb.). Lift/drag ratio was improved from -0.597 to -1.016. These changes increased total drag by 381 N (86 Lb.). Further testing lowering ride height 2.5 cm rear and 5.0 cm front reduced drag by 326 N (73 Lb.) and resulted in a L/D ratio of -1.247. Although data are specific to the Corvette C5, the general principles studied may be applied to any production-based racecar. These modifications should be validated on the racetrack prior to competing to ensure the handling balance can be optimized for the driver and car combination. "

davidfarmer

that's for a World Challenge car with splitter and wing......virtually nothing useful for a street-trimmed car.

I'd get the nose up a bit, maybe 1/2" of rake, but I'm more concerned about HOW you lowered it, and what shape the alignment is now in. We'll get it sorted out!

rustyguns

world challenge car is : " Aerodynamic Test and Development of the Corvette C5 for Showroom Stock Racing" ?

davidfarmer

Sounds like the title was imported from a foreign language! Title implies T1

waddisme

That was all the info you could get without buying the document. I figured it would be over my head so not worth the money. Maybe someone here has it.

jonnyc

i've always been told that you need to set the lower control arm parrallel to the ground.this will give you the proper ride height.the rake will just end up being what it is.

geerookie

It's a very informative read and worth the money. If your interested in racing/aero and you have a basic understanding it won't be over your head.

AU N EGL

In short

Lower the front no more then 1" and keep the rake at 1/2" to 3/8" between the front and rear A-arm mounting points.

all measurements to the A-arm mounting points.

davidfarmer

I have the spreadsheet from the actual Wind Tunnel session....... or at least one of them.

Anyway, I'm with Tom, around 1/2" of actual frame rake. OEM tires will give it to you without adjusting the suspension, track tires may need some adjustment. Then lower/raise the rear to compensate for oversteer.

z060ntrack

70mm front to rear as measured at the ball joint

waddisme

Read paper. Original WC car did not have any aero mods, but later years they were allowed. Test were done with car with small splitter and full wing and undertray. They also had some benchmark #s for stock set up but no adj.