Stock rail from the 58 frame on the right verses the modified 48 on the left.
Shows how much changed when this bend was pressed in for the bigger kick over the rear axle.
Time to make a template to replace the rusted out section. Made sure the straight lines from each side continued on.
A curve was added using the old piece taken out as a guide.
Dragged out my old anvil from when I was a Blacksmith/Farrier. This is the small 125lb one that I kept it the back of my truck when shoeing horses to alter the shoes to fit. I have hammered the new flange to match the curve of the rust repair piece.
Checking the flange to make sure it follows the rail correctly.
Patch piece tacked in. It wont be welded in fully until the fish plate behind this bend is installed. That way the bend wont alter and the weld penetration will go into the fish plate along the join as well making it stronger.
Just laying out the fish plate on the opposite side to which it will be installed. This is the way I do them using the Government Street Rod Manual as I guide and what I was taught working in the structural steel industry. Only thing changed is the radius on the ends to remove a possible stress riser there.
It needs to be of the same material thickness as the parent metal of the rail, 4x longer than the height of the rail over all. Half of it will be without taper with the remaining 25% each side tapering off to a radius 25% of the height of the rail. So in this case the rail is 4" high so 16" long with the taper on each side 4" long to a 1" radius. I just use a socket to draw around. The reason for the taper is so that there is a gradual increase/decrease in stiffness in and out of the bend. This stops stress risers from occurring. Same reason for rounding the ends as well, a point would cause a high stress concentration.
Using the frame rail from the 58 chassis to make my fish plates. The holes are a bonus as will use them to plug weld into the back of the rail.
Rail looking pretty sad now.