Quote:
Originally Posted by Cobra #3170
Well said David,
It all starts with the chassis and I'll bet your beautiful new coupe goes a long way towards resolving that issue. A stiff chassis can tolerate high loads without all the ill effects associated with a lesser chassis with the same high rate springs. I have a 2005 Ford GT that has a rear motion ratio in the high 9's and a front motion ratio in the high 8's, I run 500 lb/" front and 800 lb/" rear springs and the ride is quite tolerable considering the super high wheel rates. The secret is the chassis is over 20,000 lbs/D. in Torsion. A wimpy chassis will actually give diminishing returns if the springs and bars cause the chassis to displace under load, so Chapman's theory only works to a point.
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Indeed, indeed. This is why I enjoy talking to you (and others in the top of their respective fields). It seems we all have the same DNA; we are always trying to make things better; we are always thinking--I guess it is just part of our DNA
I am so grateful to those who came before us and so freely showed us their secrets. We truly stand on the shoulders of giants. (Who would have ever thought you could have autocrossed a 427 competitively all those years!)
I once spoke at length with an F1 suspension engineer. That was one of the most fascinating discussions I have ever had. He summed up all their suspension problems in one word, "compliance." I have never forgotten that. I constantly look for compliance in all our systems. Invariably, that is where all the problems lurk.
When we did the FEA on our original chassis it was something like 1450 pounds/degree.
Indeed, a "noodle" chassis is an undampened spring that even Chapman couldn't control. Noodles are best dealt with on dinner plates and not on the race track.
(noodle=compliance).
The backbone of the Coupe really does help stiffen up the chassis and helps the handling tremendously. However, the backbone was a stop-gap solution (probably proposed and implemented by the late Phil Remington--he was a phenomenal engineer) to figure out how to get the 289 competitive. Obviously, Shelby was quite successful with the design. When we had the car at track day, everyone gathered around the Coupe--and no one gathered around the 427 and 289 cars. I have never seen that before--even I was drawn like a magnet to the Coupe
It is a show-stopper in real life. Pictures don't do it justice. Jim Farley was there at the track, but he was spending all his time in Mac Archer's car. He asked about the Coupe but probably got tied up with his other cars. I'm sure we will run into him again. He was exceptionally nice. I brought Governor Herbert over to meet him and Jim couldn't have been nicer. Did you ever run into Jim? He was there with Raj (head of engineering and design) and I got to meet him too. Very, very nice men. I'd like to spend more time with them.
Back to the Coupe.
We have several customers who want to race our Coupes and need them to comply with FIA safety rules. Of course, we use the roll cage requirements to stiffen up the chassis anywhere we can. It adds weight (and safety
) but I think we get it back in track times.
David