kedvesh

It seems that the rear end of my C5 gets light at speed when I'm on the track at speeds above 135 mph or so. When it does, I feel I have less control over the car. As a result, I purposely limit or try to limit ( ) my speeds somewhere in the 120 mph range.

The 'Vette's already lowered a bit, but it isn't slammed.

I'm thinking the solution is a modest wing for the back end of the 'Vette. But, I don't want to get one that looks like I've "riced" out my beast.

Any suggestions (w/ website references) for something that melds funtion and form?

Thanks in advance for the advice!

John Shiels

raise the back add rake

AU N EGL

if the rear end is a bit light at speed, I would be the a few things.

1- the ride height is off
2- the rake of the car is way off
3- needs new alignment.

when all three are set properly the car does not experience that lightness

Good Luck

VetteDrmr

+1 Especially looking at your sig picture, it looks like the car is riding essentially flat. You need about a half-inch or slightly more height at the rear cross member.

Tom's comment about getting an alignment done is also good. Have you had it aligned since you lowered it?

HTH, and have a good one,
Mike

kedvesh

Hmmm. Good points. I've been meaning to take it to Phoenix Performance for a checkup. Guess I'll finally have a chance to do that when I get back from Kuwait later this summer.

Still, a rear wing or spoiler may help. Don't know though.

Any further comments from anyone or other suggestions? Thanks as always!

Independent1

Been reading up on aerodynamics lately. One of the pieces of advice they give is : "Don't try to fix a mechanical problem by using an aerodynamic fix."

I would take the advice offered by the people in this post and see if your problem is due to the current set-up of your car.

kedvesh

Mike,

Thanks for the reply. I changed my sig pic. Please let me know if this changes your remarks on ride height.

It was aligned at Phoenix Performance in Jan/Feb 07, but I pretty much drove it into the ground @ VIR and Sebring last year. As I said in my reply to Tom's post, I'm planning on taking it back there (only about 4 hours away from me where I live in the states) when I get back this Jul/Aug from my deployment in Kuwait.

Thanks! And, enjoy all the track time you can get, even with $4.50/gal gas (premium). Ugh.

kedvesh

Thanks for the post! I'd rather not have to slap something onto the 'Vette's beautiful lines. Thus, my earlier comments about form, function and "ricing".

Your comments fall into line with the others. Phoenix Perf, here I come!

Bill Dearborn

I have run my car to speeds as high as 150 and it hasn't felt light in the rear. With the correct alignment and rake you should be able to do the same. The only times that I have felt a C5 get light in the rear is under trailing throttle conditions during high speed turns and the solution to that is to add some throttle.

Bill

gonzalezfj

Make sure you tell Aquilante's crew about your problem. I guarantee they will fix you right up.

Frank Gonzalez

yakisoba

I note that the "normal" feel for a vette with stock or near stock suspension is a light feeling in the front of the car at around those speeds. Your steering inputs will be greatly magnified if you are turning going that fast, so take it real easy. "Normally" the cure for light rear in a turn is to get on the gas earlier, and make sure your alignment isn't going tow out in the rear under acceleration.

AU N EGL

I will second this one.

I have some aero things and still playing with it. Need some wind tunnel time. But a few other things come first in the budget.

mountainbiker2

I've had my car flat and on a rake and could not tell any difference. I would check into your shocks first, before I would worry about your rake.

Steve

autoxer6

How does adding rake stabilize the rear? It autocross it makes the rear much looser.

davidfarmer

I think you are feeling normal high-speed float. At 170 in the Z06 at VIR, the car dances all over the place. Same thing at Rd Atlanta. Just drive through it.....unless you really really think you have a mechanical issue.

***these cars do create lift as speed increases....that's just the way it is unless you want a wing and splitter****

Gray Ghost GS

Hey Chris, if the rear end begins to get light - give it more gas. Seriously though - if the alignment, rake and ride height are good - not much else to adjust. Did you inspect your suspension components, e.g., shocks in good shape or sway bar endlinks loose? Mike

TheSkunkWorks

Agree I'd 1) verify there's not a mechanical setup issue, then 2) try some rake, then 3) go with real aero devices, in that order as required. IMHO if performance is a real priority, adding such functional bits will become aesthetically pleasing to you in the long run.

autoxer6, to oversimplify the difference... at lower speeds mechanical grip is the first order factor in play, whereas at truly high speeds downforce (or the lack thereof) becomes the first order factor.

kedvesh

Mike,

Thanks for the reply! Hope all is well in VA. Only about 7 more weeks left.

As I posted earlier, a run up to Phoenix is in order upon my return. After all the track time I did last year (w/ one suspension check in the middle), things may have gotten out of whack again by the time of or during my last event (Sebring in December w/ Chin Motorsports.) Entering Turn 17 at one point on Day 2 was not the most fun experience I've had on the track.

John Shiels

creates low pressure area under the car

AU N EGL

which sucks the car down onto the track. Bernoulli effect as in sailing, the wind does not push the sails, the wind pulls the sails with a low pressure gradianed in front of the sails and high pressure in back of the sail.

Low pressure under the car, vs high pressure on top of the car, pushed the car into the ground. Improper rake, and there is less low pressure under the car.

http://www.sae.org/servlets/productD...D=2002-01-3333