making an aluminum hood

Yesterday we noticed that the Camaro hood is very light and made from aluminum. Has the great power bulge down the middle I need too. If I lay the TR8 hood on top of the Camaro hood, there is plenty of overhang all the way around. I want to trace the edge of the hood a couple of inches bigger and cut the shape out of the Camaro aluminum skin. Then I can fold the corners over to keep the shape. Whats the best lightest way to make a frame for the backside to give it a little rigidity? Using the TR8 framework is not the option I want to use, because it fouls the forward roll cage tubes that run from the cage to the front and hold the fenders in place. On fiberglass hoods, I've used wrapping paper tubes cut in half and then glassed over. This time I'm thinking aluminum tubes bent and epoxied to the skin. Hood is going to be a pin on. Any other ideas? How do those circle track guys make their own hood frames?

If you're making a hood, why not try making a fiberglass one? You can make a mold for the top side using fiberglass, adding any bulges you want onto the stock hood first, then use that to make the top surface. Once you've got that, add a thin layer of foam, balsa wood or something similarly lightweight for a core, keeping it a few inches in from the edges. At that stage you can also add any other reinforcements you may need for hinges, latches, prop rods and such, then simply glass over the underside. Should be lightweight, stiff and much easier than trying to recreate the factory bracing, which is optimized for mass production in metal, not ideal properties in composite.

I have made fiberglass ones before. Even have a mold to make as many as I want. I want to reuse the Camaro hood because it has the power bulge I need to help clear the LS3 I just installed in the TR8. Just think in this case, the aluminum one would be better and much less work. Just looking for ideas to make a frame on the back side. Unless someone comes up with a better idea, its aluminum rod bent to shape, epoxied to the back of the skin.

I think you could do it with fiberglass just as you would on a fiberglass skin.

Got a sheet metal brake? you could notch it to match any curvature and epoxy in place. Even a small rib would add a fair bit of rigidity.

Sheet metal brake, check. Going to use it to fab up a new tranny tunnel if it doesn't rain tomorrow. I like that idea olden. Cheaper than going out and buying 20 feet of aluminum rod.

Do you know what kind of AL it is? It might not like being bent and reshaped. Annealing may or may not help depending. I would go with oldtins idea and punch some holes and make the stiffening rings or whatever the right name for them is. Hammer them against wood holes or maybe try making the tool below with some bearings and some scrap bar stock.

In reply to jere:

Dimple dies.

These ones work awesome:

SWAG Off Road Dimple Die sets

If any of the Camaro framework is left expanding foam has amazing stiffening qualities.

oldtin wrote: Got a sheet metal brake? you could notch it to match any curvature and epoxy in place. Even a small rib would add a fair bit of rigidity.

Do you have access to a beadroller?

The shape above could be done with a step-die (with a pass on each side). You could cut a one piece frame and then roll the inner and outer edges.

How much shape do you have to accommodate? Do you have a shrinker/stretcher?

I would be tempted to lay down strips of foam glued in place and lay fiberglass strips over that. The foam can easily deal with any curvature of the alloy skin.

Not liking the fiberglass idea because it will have to be layed up off the car. The aluminum skin is going to be floppy off the car. Unless the final shape of the fiberglass is perfect, there will be no way of changing the shape afterwards. The more I think about it the more I like the aluminum rod idea. If the hood doesn't lay perfect, I can still tweak the shape of the hood with wooden blocks and a little brute force. Watched a video made by Joe Gibbs racing. His hood builder uses steel rod on a steel hood skin. He makes 80 hoods a year and has a buck made to hold everything in perfect alignment as he tack welds them together. Then the hood goes with the rest of the car to the body shop where they further refine things. Have a look at a 2010 Camaro hood. Its pretty much a big flat piece of metal with a power bulge down the middle. Looks like you can cut out just about any basically flat hood from it. Flat on the front and sides just like a TR8 hood. No curves or turn downs at all.