Would 11 gage ford steel be as strong as 11 gage mild steel? Or do I need to go thicker for making the 1926 coupe inside tire mount bracing?
I would use .125" 4130 steel rather than mild steel. The Ford steel of most of the Model T era was a vanadium steel. Mild steel will be too soft and pliable to replace Ford steel of the era.
No vanadium in the bodies. It was all cold rolled low carbon steel. (Including the brackets.)
I cut a piece of 1.5" by 1.5" by 0.125" thick square tubing to match the contour of the panel. Then rolled a piece of 1/8 by 4" wide flat stock to fit the contour of the panel (& the cut tubing). welded box to plate and attached to top cross member. Seems to be staying put. respectfully, jb