This long A$# post is from the 2022 Ford Body Builders Layout Book.
https://www.fordbbas.com/publications
The following recommendations should be heeded to maintain proper function and performance of the vehicle frame: • Use existing holes in the frame whenever possible. • Holes are not to be drilled in the top or bottom flange of the frame side member, or in locations on the vertical frame side that would weaken the frame. • Holes to mount brackets, out-riggers, and supports, may be drilled in the vertical frame side rail web with the following restrictions: o There must be a minimum of 1.5 inches of material between edge of hole and inside of upper or lower flange. o The minimum edge distance between any two holes up to 0.625-inch diameter must be 1.00 inch. For holes larger than 0.625-inch diameter, the minimum edge distance must be 1.5 times the diameter of the largest hole. o The maximum hole diameter for any hole in the frame is 0.75 inches. o Avoid drilling holes within 0.5 inch from the edge of any existing or added reinforcement. • Avoid close vertical succession of fasteners (3 holes max). • Adding holes or welding on frame cross members is not recommended. • All attaching fasteners, including flat washers, must be of high strength steel (Grade 8 for SAE fasteners, Property Class 10.9 for metric bolts, PC 10 for metric nuts). • Prior to welding, plasma cutting or any other operations creating heat, any parts which could be damaged by excessive temperatures should be removed or adequately shielded. • Ensure the welder ground return clamp is positioned as close to the affected welding area as possible (not more than 12 inches). The welder ground return clamp should be on the same frame being welded upon. Welding cables should never be allowed to lay on, near, or across any electrical wiring or electronic component during welding. After welding, when parts are cool, carefully inspect wiring and electrical components for shorts or other damage which could draw excessive currents and possibly cause an electrical system short when the 12v battery is reconnected. • Do not weld on frame flanges, including the bend radii. • When welding steel side rails, emphasis should be placed upon weld application techniques to avoid stress risers that may adversely affect frame operating stresses. • When welding within 4 inches of any cross member or suspension rivets, remove the rivets and replace with appropriate threaded fasteners (Grade 8 for