Okay, I've noticed that on my lovely ole F-600 that the frame has been lengthened many moons ago, there is a section that is a few feet long, added to the middle of the frame members behind the cab, welded on both ends to the existing c shape frame members, it does not have another channel inside it, like a double frame would have. The member is a C shape, typical of a truck frame. The vertical welds were placed from the inside and look professionally done, excellent penetration, profile is very flat and there are no cracks and or significant stress issues, it's been that way since new or close to it. I did notice that on the lower portion of the "C" channel at each joint, on the inside of the "C", small splice plates were added where you can lay them flat, I'll call it the top side of the bottom flange if you raise the body and look down on it. They overlap the main vertical welds and have held all these years, but the plates are seperating from the frame now. The beginning of the vertical welds on the bottom flange may have some small issues as well, but nothing has been overstressed, now is the time to correct this, I'm sure after a few more years it could be a real problem. The weld profiles do not look large enough and probably should have better penetration on these plates, unlike the main vertical weld, which is nicely done. I can see why this is occuring some stress and or forces have caused the plates to seperate. What I would like to do is reinforce the frame along this lengthened area, but wonder what the best configuration would be. I could easily re-plate the bottom flange exactly as is now, but also wonder if I were to place a member inside the existing C frame members and extend it to overlap beyond the vertical joints of the extension piece added years ago, by either stitch welding it or continously welding it, with the shape I propose, a bent plate or modified C channel that would just have the bottom leg to stiffen the bottom flange of the existing flange and return upward say 3/4 of the way up the existing web of the C shaped frame member. Not having the upper flange which would allow a good angle for me to weld along the top edge on the web of the existing,or would it just be better use a full C shape and weld along the edges. Reason for this, to substantially reinforce the area if this can be done. Knowing that these small splice plates held for all these years, its current condition and the fact that I'm not going to carry anything heavy all loads are light materials, nor will I be going off road into places that will contort or place a lot of stresses on the frame, say like a dump truck working on a rough site. I think it's possible to remedy this but have a few concerns based on some knowlege of the subject. I know the orientation of the areas where welds are to be placed may need to be considered, but don't know if what I think may work is ridiculous or should be a straight forward repair if done properly. If I over do it and stiffen things too much, will the reactions create other issues where the new connections end ? As usual, smoke is pouring out and I'm overthinking things a bit ! The truck is a 1964, it's old, I know and have read the labels on many much later model trucks that clearly state not to drill or weld to the frames probably due to the treatment of the steel being hardened. I'm not sure what the existing material is here and want to make sure it can be reinforced without creating other problems or stresses. Correct surface preparation, pre & post heating if needed, plan to use 7018 1/8" electrodes. I plan to use A-36 mild carbon steel or what would be recommended, thickness's of the existing are approx. 1/4" or 5/16". I suspect that the steel used of this era may be more tolerant of welding, it may not be hardened and I am confident I can place a good weld with the set up I have, Miller trail blazer NT-250, using 1/8" 7018 electrodes, or the next size up, 1/4" welds or a bit larger with good penetration, I can do it in the positions I need to without much difficulty. I don't want to over do it, too much penetration, create brittleness around the surrounding areas or anything bad I am not aware of here. I will take some photos and learn how to post, possibly annotate them, probably much more helpful than this lenghty post, just that it's something I have to do, had I known I'd probably not bought this truck, but once you are in, there's no turning back. If the frame were really over stressed, I'd chalk it up as a loss, but I think it can be done without worry, might need a few tips to help do a neat but strong job correctly, the guy who inspected the truck and has many many years owning a truck repair shop across the street would have probably told me if this could not be done, but I am a bit out of my area of expertize here, be great to hear any thoughts on the subject, do apologize for the over lengthy post, photos would have been better 1st.
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