It'll take someone who was tech or engineer in F55 development to answer this precisely but I'll spit it out anyway and hope.:

1. Will increasing the swaybar diameter (say to Z51 or Z06) seriously reduce the F55 computers ability to maintain a stable platform?

2. How sensitive is F55 to changes in unsprung weight? If I changed to bigger disks and calipers (heavier?), forged wheels (lighter) or aftermarket Z06 wheels (heavier) does this seriously alter the damping?

3. I can't imagine "tuning" F55 like some people can do with engine management, but are unsprung weight and/or swaybar stiffness externally-accessible tuneable constants?

 

Probably!

 

I think he was looking for something a little more technical!

 

Well in that case............"Possibly."

 

 

Stronger sway bars will help stabilize the car and should only help F55, from a performance perspective.

I have no idea how sensitive it is to weight, but I would imagine that changing unsprung weight will have some effect on the system. You can think of the suspension as a spring-mass-damper system with the road applying external forces. F55 replaces the damper with one where the damping rate is continuously varied by the computer.

Less mass will allow the system to displace more, and is easier to control. Damping force is directly proportional the the speed of the suspension movement, but with the computer varying the damping rate, I guess the effect depends on how the computer is tuned to react. It may not matter at all.

 

what did you expect from me? He said it would probably take an engineer from GM. Heck, I just sell light bulbs

 

Are they the "bright" ones?

 

I just sell them - it takes two aggies to install them, so I never get to see how bright they are

 

I understand the mathematics of classical second-order systems. But it's a long, long line from there to the Corvette suspension, and because it's nonlinear that ain't a straight line.

I'd like 14" Z06 disks and calipers on my car for slightly better stopping (when its not tire limited), less fade and increased longevity of the thicker rotors. I HATE it when the GM rotors warp and they tell you the solution is shaving even more metal off.

So back to the original question(s). Will the control algorithms be upset by the larger unsprung mass of bigger brakes, or do numerical coefficients need to be changed? CAN they be changed via the CAN bus and (if so) does anyone know how?

Z06 brakes have to be heavier, and that means increasing shock stiffness, obtained with more shock current. Does the controller have enough output current to cope with, say, 10% higher unsprung weight?

I don't think thicker swaybars would bother F55s computer too much, and compared to big brakes trying those its inexpensive and easily reversed. But if someone knows approximate answers to the brake weight question, they probably know ahead of time whether the swaybar might cause a problem.

 

From what I have read I doubt the sways will throw off the F55. Have a look at this link if you haven't already.

http://www.corvetteactioncenter.com/....php?qstId=503

 

Thanks for that link. I've read stuff like that, and that is somewhat dated, but what caught my eye was:

"MR's position sensors measure each wheel's movement. With that data, the controller determines three types of body motion: pitch, roll and heave. "Pitch", (front end moves up or down) and "roll", (the car leans)..."

That sounds good: if roll can be sensed seperately from pitch and heave, then a change in the sway bar stiffness might not have too much affect the controllers reaction to the other two. As I said, changing the sway bars is a few hundred dollars for Z51 swaybars and is reversable if it turns out to be a bust.

Road and Track, whose judgement I've put to the test in the past and never faulted, said Z51 for smooth track and racing, F55 for everyone one else who didn't choke on the price.

OH S--T! Down further in that article is a jewel:

"On relatively smooth roads near the car's limits in abrupt transitions and turns at high lateral acceleration, a MR car's base springs and stabilizer bars show their inadequate roll stiffness. Sources tell us that DIY tuners can trade a little isolation to make up some of this roll stiffness deficit by adding Z51 stabilizer bars to MR cars. A C5 in the hands of a talented, aggressive driver will react well to that change."

THAT doesn't leave any question in my mind: I want the stiffer bars. 'Course any answer brings up another question: would C6 Z06 bars be even better?!

I consigned my C6 Z51 to the dealer today. The F55 car should be here before Thanksgiving. I'll drive it stock for a while to familiarize myself with it before changing the bars, but that's something I HAVE to do. The brakes can wait until the 14" parts become readily available and maybe someone with inside information can give a thumbs up, or thumbs down, to the additional unsprung mass.

Thanks again for that link.

 

Put Z51 bars on my F55, best money I ever spent! Much better handling, no down side that I know of....

 

 

Although, I found this interesting: "On Germany's bumpy, challenging Nuerburgring circuit--an increasingly popular suspension-development venue--they report that the F55-equipped Corvette is actually quicker in the Tour mode."

Link for that is: http://motortrend.com/roadtests/coup...0208_corvette/

Nevertheless, I am going with the Z-bars.

 

And that was in the 2003 model year. C6 is stiffer, a better starting point. It's softer runflat sidewalls and noise-specific insulation gives the F55 engineer(s) more to work with. So fatass F55 is in and boy racer Z51 is out. I decided that some time ago. But like many only-two-choice decisions, what about ME? I'm not fat OR a boy.

Z51 swaybars on F55 looks like a reasonable starting place for mods. So that's half the question sorta answered.

The second non-Z51 issue is Big Brakes. I don't especially want the cosmetically crossdrilled Z51 brakes, I want the serious Z06 brakes. Better yet, NOT-DRILLED aftermarket Big Brakes. But their multi-thousands cost is outa sight for me. I can't get either just to see how F55 handles the extra unsprung weight.

What I'd love to hear, from someone who really knows, is "IT'LL DEGRADE WITH MORE WEIGHT" or "ITS ALGORITHMS WON'T BE BOTHERED MUCH".

Idaho road surfaces are probably closer to Nurenburgring than it is to LA or FL roads. Right now big trucks are moving potatoes from fields to storage sheds and there are potatoes laying on the road at RR track crossings and bumpy, sharp corners. You street drag here I suspect you'd get wheel hop from hitting potatoes in the road.

 

Potatoe hazard? That's a scary thought, especially for motorcyclists.

 

They can be potatoes, but they also are moving BIG sugar beets. Those catch on the bottom of airdam of the C6 and thud around. A motorcycle would probably get airborne.

They can't get on the highway without covering the trucks. But I live 3 miles outa town and a farmer built a big storage shed on the road into town. Tere are trucks standing in the little country road, waiting to unload and none of them are covered.

But ya gotta count your blessings: at least they aren't rocks.

 

I also plan on putting Z51 bars on my F55 and will be replacing the tunnel plate with the ceramic coated unit from LAPD or the unit from Elite Engineering.

 

You know, billsee, I went on the GM web page and somewhere under "contact us" there was a place to ask GM a question or make a statement -- with the disclaimer that they probably would consider your inquiry prosaic and never respond. I suggested they educate their dealers about the F55. And they shot and email back to me in 24 hours saying, basically "right on -- we're taking care of that problem." Why don't you ask them your unsprung weight question? Keep us informed.

Personally I think the Z51 is an over-with technology with a very narrow purpose when compared with the astounding F55.