Kirkham Coupe Test Day :)

[David Kirkham]

We had a test day our at Miller Motorsports track on Saturday with our new Coupe. Everything ran really well. It was a great day



David

[dallas_]

Dang that's sweet!

[ERA Chas]

I though you were now the governor David?
The Coupe driver was using the 'rain line'...

[David Kirkham]

Originally Posted by dallas_

Dang that's sweet!

Thanks

ERA,

I still work with the Governor on legislation. We actually get along quite well together. I'm glad he is a friend. He had a great time in the car.

David

[ERA Chas]

I would have too David and I'm a Nobody...

[fordracing65]

We all know he uses all your ideas, that's how he (Gary) is so successful.

[David Kirkham]

Originally Posted by ERA Chas

I would have too David and I'm a Nobody...

One thing I have learned in politics is that everyone is someone--no one is a "nobody." Yelling and hating doesn't get things done; it just alienates people. Making friends, even with those you disagree with (come to think of it--especially with ones you don't agree with) is how we move things in the right direction.

David

[Cobra #3170]

Originally Posted by David Kirkham

We had a test day our at Miller Motorsports track on Saturday with our new Coupe. Everything ran really well. It was a great day



David

Boy, that roadster needs some springs!

[thndrrd]

I'm suprised he can handle a standard transmission.

[David Kirkham]

Originally Posted by Cobra #3170

Boy, that roadster needs some springs!

Oh yes. Thomas likes his car sprung soft for street use; so, he decided not to change the springs (this was really a test day for the Coupe anyway). After watching the video I think he is changing his mind

David

[Cobra #3170]

Originally Posted by David Kirkham

Oh yes. Thomas likes his car sprung soft for street use; so, he decided not to change the springs (this was really a test day for the Coupe anyway). After watching the video I think he is changing his mind

David

Yes, those short little suspension arms with no camber gain do not cope well with large chassis roll angles

[David Kirkham]

Originally Posted by Cobra #3170

Yes, those short little suspension arms with no camber gain do not cope well with large chassis roll angles

3170,

Yes, the suspension has been on my mind for quite some time now. Thomas and I are really working hard on trying to figure out how to decouple roll, pitch, heave, and warp--as you know, this is a bedeviling problem. There are no free lunches and controlling one inevitably "controls" another one (in a way, it always seems, that you don't want)! For the track, it seems Chapman's saying, "Any suspension will work--if you don't let it!" is the cure for Cobra ills. 1000 pound springs work well on a smooth track, but not on our customers' bums as they drive down the street

Our conversations in the past on suspension have always stuck with me. (I always remember what you said about hitting pot holes with the brakes on and watching the loads skyrocket.) There is an answer to this problem--we just need to find it.

David

[Cobra #3170]

Originally Posted by David Kirkham

3170,

Yes, the suspension has been on my mind for quite some time now. Thomas and I are really working hard on trying to figure out how to decouple roll, pitch, heave, and warp--as you know, this is a bedeviling problem. There are no free lunches and controlling one inevitably "controls" another one (in a way, it always seems, that you don't want)! For the track, it seems Chapman's saying, "Any suspension will work--if you don't let it!" is the cure for Cobra ills. 1000 pound springs work well on a smooth track, but not on our customers' bums as they drive down the street

Our conversations in the past on suspension have always stuck with me. (I always remember what you said about hitting pot holes with the brakes on and watching the loads skyrocket.) There is an answer to this problem--we just need to find it.

David

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.

[AL427SBF]

For a nominal consulting fee along with NDA on proprietary engineering, contact Richard Hudgins/Larry Goins (of JBL fame) for an elegant edge of the art solution

[David Kirkham]

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.

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

[MAStuart]

Hi David Thank for posting the vid . Your coupe keeps me inspired to work on mine. Any chance you have a picture of the roll cage. I was wondering what it would take to race one . I had some friends help me work on mine last October. I thought you might enjoy seeing how my body is coming along. Metal Meet Forums

Mark

[David Kirkham]

Originally Posted by MAStuart

Hi David Thank for posting the vid . Your coupe keeps me inspired to work on mine. Any chance you have a picture of the roll cage. I was wondering what it would take to race one . I had some friends help me work on mine last October. I thought you might enjoy seeing how my body is coming along. Metal Meet Forums

Mark

We post pictures on our Facebook all the time. The next two Coupes we are making won't have the roll cages. But, we are making a lot of them right now. Keep checking Facebook and you will see lots of pics in the future.

David

[David Kirkham]

Originally Posted by MAStuart

Hi David Thank for posting the vid . Your coupe keeps me inspired to work on mine. Any chance you have a picture of the roll cage. I was wondering what it would take to race one . I had some friends help me work on mine last October. I thought you might enjoy seeing how my body is coming along. Metal Meet Forums

Mark

Do you have any other pics I could see? I can't seem to access the ones you posted. I ALWAYS love to see how other guys do things.

David

[MAStuart]

Sorry about that David, the link works for me but you have to scroll quite a because there are a lot of pictures. Has anyone else tried the link? Were you able to get to the site? On my thread in the scratch builders forum on Club Cobra I have one picture of how the body is looking and others of the chassis. I don't think you need to join metal meet to look around. I'll ask or see if I can find out what the problem is. Mark

[MAStuart]

I signed out at metal meet and came back to this thread and clicked on the link, it should work, but some of the pictures you can look at directly, the rest you will have to click on the link for that picture. Mark