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COE trucks are very cool,...
COE trucks are very cool, indeed. This column addresses some issues that may come up with firewalls on these plus-sized vehicles.
Ron, I am in the process of installing the firewall and floor boards in my ’52 Ford COE dualie pickup. The engine has been moved rearward 30 inches, and down 11 inches to get more space in the cab. The new firewall will be made of 18-gauge steel, and it will be completely flat, approximately 44 inches wide by 18 inches deep. My question is, how important is the direction of the rolled beads that I will add for rigidity? The left side of the firewall will help support the steering column and brake pedal mount. The bottom of the firewall panel will have a 30-degree roll or bend to align with the floor boards, and it will be flanged its entire width.
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As nearly everyone has seen, most automotive and truck inner panels are reinforced with ribs or beads, and these are put there to improve the rigidity of the panels. In some cases, the extra rigidity is necessary to ensure the panels do not “drum” with road vibration. In other cases (such as ribbed floor panels), the ribs give the panels extra strength against bending. Of course, the size and direction of the beads can have an effect on how much stiffness they add to the panel.
With pendulum pedals, the pedal mounting needs to be extremely strong. In a panic-stop situation, even an average-size person can stomp on a brake pedal with well over 300 pounds of force. Therefore, your firewall alone is probably not sufficient for mounting the pedal assembly, even if it has large beads. I would recommend making a structure from square tubing, mounted just inside the firewall, which the pedal assembly would attach to. This tubing structure should probably span the entire width of the firewall, and attach to some strong portion of the inner cab structure, like the door jambs, to have sufficient strength.
The steering column does not need nearly as much support, since you will probably use a column mount under the dash, and many steering columns attach directly to the steering box, giving them great support there. If the column has a universal joint at the bottom end, you will need to give the column additional support on the lower end, but if the firewall you are making has a continuous flange on the bottom edge, that will probably provide sufficient strength.
So, the primary benefit you’ll get from putting beads on your firewall is to help prevent drumming, and to help keep the firewall from warping as much when it is welded into place. In this situation, you can run the beads pretty much any way you like! Often the throat depth of a bead rolling machine will determine what is possible, and what is not!
Hope this helps, and write again if you have further questions. I’m very glad you enjoy my columns!