New aluminum Cobra Chassis pictures

[john chesnut]

I am busy finishing up my new aluminum chassis and thought that you guys might like to get a look at it. I know that I will be "stoned" for putting a Chevy engine in it but that is what I had. A Ford will fit too!! For complete info go to www.dragonmotorcars.com and click on C5 Cobra.
This chassis is designed to take several different bodies, An accurate Cobra, Cheetah, Daytona Coupe, 23 style T bucket, and even a Lotus 7 inspired body. ( A complete Cobra weighs right at 1900lbs!)
I will debut the chassis at Carlisle. I know that my chassis is not traditional in any means but I wanted a "Modern Super Car wrapped in Snake Skin!" I will soon be offering kits and begin advertising on this site in a few weeks.
Let me know if you have any questions or comments. I have a pretty thick skin! Have a great day! John

[Hexnut72]

So do you use the Corvette transaxle or just the diff? Is the diff from a C5 as well?

[mr bruce]

very interesting. what is the fatigue cycle on the aluminum frame

[Doug I]

could you resize the linked photos to be a little larger ?

[Hexnut72]

Bigger pics on website:

http://www.dragonmotorcars.com/CobraC5Nav.html

[john chesnut]

I use the diff from the C5 but not the transaxle. Using the Transaxle would have resulted in a very wide transmission tunnel. A machinist friend of mine and I engineered a conversion to allow the use of the diff with a driveshaft. The rear cradle has essentially an "engine plate" welded in that the trans tunnel is welded to. The diff bolts into this plate. The tunnel becomes a large torque arm for the chassis. Virtually any engine and trans combo can be used as I have a bolt in tranny mount that can be placed in the proper position.
To make the C5 parts work required new chrome molly axles which are 1 7/8 inches narrower, the diff conversion, and a new steering rack as the front track is substantially narrower. 315 front tires and 345 rear tires will fit with out modifing the body. 295s are shown in the rear, 275s on the front, both on 18 inch rims.
The over the top headers allows for long and wide footboxes. It is 47 inches from the back of the cockpit to the pedal faces with 15 1/2 inch width at the pedals. The cockpit takes up to a 20inch wide seat.
The rolling assembly as shown weighs 1488 lbs (Without me!)
Thanks for the question. John

[john chesnut]

I am a clutz at the computer and could not figure out how to make the photos larger and still get the site to accept them. I will keep trying. My web site has larger ones www.dragonmotorcars.com. Click on C5 Cobra to see everything.
Good question about aluminum fatigue cyle. I honestly don't know. I based my design and material specs on Herb Adams aluminum chassis that was available in the 90's. He was a pretty famous chassis engineer at Pontiac and wrote a book on chassis engineering. I have a GM chassis engineer that is finishing up one of my Dragons. I will ask him direct me in how to have the chassis evaluated for this and will report my findings. My frame is constructed of 100% T6-6061 material. It consists of a space frame that is constructed of 2X2 3/16 and 2X4 1/4 tubing. All of the shear panels and trans tunnel is from 1/8 sheet. The suspension pickups, lower are from 1/2 and is machined so that the stock Vette concentric alignment system is maintained. The upper control arm mounts are 3/8 in front, 1/4 in the rear. The front and rear clips are 1X1 and bolt on. They are designed to give before the main chassis. There will be 1X4 side impact beams with frame mounted stops that mount to the inside of the door. These will double as arm rests.
I do not use spot welds. Except for the floor which is MIG welded, the entire car is TIG welded. All of the panels are continously welded on both sides.

[john chesnut]

Mr Bruce, I have an answer for you. The following is a quote from Fred Wood, a retired GM chassis engineer. I had posed your question to me to him.
"This would normally be done on an MTS Hydraulic fixture which would alternate beaming and torsion alternating inputs for a set period of time. Stiffness would be measured before and after. I do not think that this is something a small manufacturer can do. Very expensive and complex. I think the best you coul do is measure the torsional stiffness of the frame new and then do it again after extended use. The way you have that frame designed I can not believe it is an issue. You could show a picture of the Shelby series 1 frame compared to yours, as it would compare very favorably. Fred"
I will be testing for torsional stiffness next week, after the frame is completely welded. I will let you know the results.