After removing the body I discovered this crack in the frame. It looks like someone tried to repair it in the past (maybe) and originates from the front passenger side bed mount. Is it a reasonable idea to repair this or is this a deal breaker for this frame? I want to know the frame is sound before purchasing all new suspension for it. Can I mig weld on this older frame? Does welding the top crack flush and welding a diamond shaped piece of flat iron on the inside of the frame sound like a good plan. As always, any input is appreciated.
Thank you

 

That's a pretty common crack area, and can be repaired in a number of ways. "Fish-plating" (diamond-shaped piece) is one, in conjunction with grinding out and welding the crack. A search on here should turn up several past repairs.

 

In my opinion, your stated method of repair is very good. Only thing I would add would be thick washer to the inside of the hole. Others might not agree.,...jack

 

IMHO, depending on the intended end use, it's usually not wise to change the section modulus from side to side. You can weld and flush grind the crack, and then "L" or "C" sister the frame (both sides) as opposed to a short fish plate.

 

I understand your concern. There are also concerns with leaving the work-hardened metal around the crack. These frames are very mild steel. Some kind of stress relief after welding would be appropriate.

 

when i worked in a semi shop we did a lot of lengthening of frames and frame repair. preferred method was to insert a section of steel( "L" or "C") that fit tightly inside the frame rail and then bolted together. welding the top or bottom flange is prohibited. if you weld the crack it will crack again. to keep the crack from growing drill a 1/8" hole at the end. your local steel supply should be able to make what you need.

 

Semi's use heat-treated high strength steel, while our frames are mild steel. Heat-treated steel can't really be welded in the field. You're correct that welding across a flange is bad practice. That's the point of the fish-plate or other reinforcement, to take stress off that weld.

 

I agree with dans 51 F2 except that I would recommend using a 2' long section of U channel bent to nest exactly inside the frame. Any local fab shop should be able to make it up for under $25. Try to get them to use steel close to the thickness of your frame. Finally do not weld it rather bolt it in place since it is obvious that your frame has been overheated and is brittle. Make sure that you use rustproof paint on the inside of the old part and the outside of the new part after you drill your holes to prevent future problems.