When cutting crush panels, make sure you have a good supply of cardboard or, better yet, thick poster paper, on hand. You can cut pieces away and tape them back on as much as you like until you get the shape that's a perfect fit, and it's a lot cheaper than going through several sheets of aluminum. Once you are happy with your cardboard pattern, use it to trace the shape onto a piece of aluminum (or steel if you prefer) sheetmetal and cut it out. If this is your first attempt at building crush panels, you may want to give yourself a margin for error and cut a little on the outside of your markings. Use a bead roller to run a bead approximately 2 inches from the edge all the way around the piece. This gives the panel additional strength at the edges where it will have to attach to the car. Finally, a bead of silicone-especially on crush panels that separate the cockpit from the engine bay-helps keep carbon monoxide, dirt, and everything else away from your driver.
Can You See Me Now? From there it was on to the installation of the windshield and widows. Up front, the safety Lexan is 11/48-inch thick; for the rear window and side windows behind the C-pillars 0.060 Lexan is used to reduce weight. As mentioned in the first installment, NASCAR requires a stock roof for Late Model Stock racing, and the lip is recessed to fit OEM winshield glass, which is too deep for the Lexan we are using. So, for the tops of the front windshield and back glass, spacers had to first be pop riveted into place so the Lexan would sit flush where it meets the roof. This is not necessary on the side windows because they fit into ARP's fiberglass panels. Everything is then pop riveted into place (Davis uses only steel-shank rivets, available from Fastway Racing Products, throughout the car because of its higher shear strength).
The front and back "glass" must also be secured in place by two exterior straps. Our rules say they must also be bolted into place. We used thin aluminum strapping bolted into place with button-head screws to meet regulations and keep the exterior profile as smooth as possible. On the inside of the rear window, aluminum brackets were fabricated to hold the bottom of the rear window in the desired location. At speed, low pressure air rushing past the rear window will try to pull the thin Lexan out and cause it to almost bubble out. The brackets simply help the 0.060 Lexan maintain the desired shape.
The Cool Factor The most complex part of this install was the radiator, grille, and radiator box. The grille itself was easy: ARP makes an inexpensive grille insert that simply rivets into place once you have cut the marked opening out of the bumper cover. Davis likes ARP's grille design because it does not sit flush against the exterior of the bumper cover, but is recessed about an inch with a radius leading to the opening. That helps direct air into the opening instead of allowing it to slide off the sides. Davis says this design is effective enough that you can actually see a difference in engine coolant temperatures with no other changes.
"That radius leading to the recessed grille, from my experience, will lower the coolant temperature an additional 20 degrees under race conditions," Davis says. "That's a big deal to me, because now I have a cushion. To get the water temperature back to 220, I can put more tape on the car, which will give my driver more downforce. It's pretty simple: The more efficient you can make your cooling system the more you can close off the radiator opening. That gives you more downforce, which makes for a better-handling race car."