replacing a frame-but it burned! any ideas?

so, to start off, my frame is shotty, at best. crack repairs, repaired repairs, repairs over those ones...cracks here and there. ugly, scary, drivable?, what were they thinking here?, etc. these are all words, phrases, questions that come to mind when on a creeper and wheeling around under my jeep. this thing went through a lot (including a rollover or two i believe) before i got it, and at least one of the previous owners had some bad ideas on how to fix problems...

so i was pulling a couple parts off another 73 cj5 which was burned and totalled out, and being scrapped out by a friend of a friend, of a friend. he first offered me the whole rig for $500, i just wanted my steering parts and be gone. but said i may be interested in the frame. later the frame was offered to me for $100...

so i spoke with a friend's father whos opinion i value (physicist and long time offroader-land cruiser guy)...
he said when metal gets burned/has fire on it/gets heated incredibly, it will strip the paint off then remove the oils from the surface of the metal and cause it to rust. however, instead of the normal surface rust, it actually goes deeper into the metal, penatrating it and being worse off. (i spoke to him when the cost was $500)

the condition of the jeep was as follows: fire started at the gas tank in rear, burned the hell out of the tail end, rears of both rear leaf springs were melted and caused them to bend at about 90 degrees right next to the shackles. rear body mounts were toast... moving forward, the fire burned through the interior of the jeep, and on the body. paint job was ruined, interior was gone and fried. i would say no to the body, even though much straighter than mine-which i do not care about looks of my body as it bounces off half the rocks it finds. the fire looked like it followed the fuel lines a bit, really the frame did not look too bad, anywhere. all the body mounts were not burned. acutally looked just fine (besides the rearmost, which i mentioned). the fire also burned in the engine compartment; carb, hoses, power steering lines, belts, etc were all burned...

all in all, frame looked nice. VERY STRAIGHT, no patches and cracks... as far as i could see/find on it. my area of concern if i were to pick this up would be the rear end of it where the fire was hot enough to melt the springs. in this case, i think i would cut off and rebuild the rear foot/foot and a half. not a big deal as it would allow me to integrate a custom bumper and tire mount.

QUESTIONS:
:?would the heat compramise the frame in the sense that it would be more brittle?
:?as i mentioned, all body mounts were in good condition and not burned, is that a sign that the frame should be fine in those areas as well? no melted ruber, not too hot?
:?has anyone else heard what my friend talked to me about regarding not using metal if touched by heat/fire-leading to bad rust?
:?i feel that since the frame is so much straighter and is not full of cracks and patches, it would be a great candidate for a frame swap project. i would blast the whole thing and repaint it all, and build from the ground up. i feel it could NOT be worse than what i am on, am i wrong to think this?
:?does anyone out there think 'go for it', or 'find a different one'?

i appreciate any and all input, thank you.
happy wheelin'

 

When metal gets to hot in an open atmosphere it oxidize's, this oxidation looks like rust but tends to be flaky and comes off when you rub it, the metal will be extremely fatigued at this point. It takes about 900-1000* to do this. If the paint isn't melted or the rubber isn't melted the frame is fine. If the rubber was burned up the temp made it to around 400-500*.
The frame is not high carbon steel so the heat would not make it brittle.
I say go for it.

 

ok, so it sounds like i'm gonna go for it and see if it is still available...
next question is: if it is in good condition and usable, should i, or should i not 'box the frame'?
i almost think i should just start a new thread with this...
i have read many articles that say don't box it, these frames are meant to flex/bend. i'm also of the school of thought that a frame should be mostly rigid, and a good suspension should be designed to flex and articulate, not the frame.
one article i keep referring back to when thinking the benifits of boxing it, mainly so it does not end up like my current one.

"Boxing the front frame horns is necessary if you are going to install Saginaw steering (power or not). My welder informed me that every time you weld on these cold riveted frames,they get brittle around the welds. Boxing the entire frame is a mistake, as the CJ-7 has proved -- water and debris get inside and rust the frame from the inside out. These old girls are supposed to creak, pop and moan as they climb rough terrain -- I'd be creakin', poppin' and moanin' a lot louder without mine."


that is one persons quote regarding this. thanks for the help.

 

anybody reading this with info as to boxing the frame or not, or anything else, regardless, i am starting a new thread to bring it to more attention and recieve more replies on it. please post on that one if you have any info or opinion.
thanks a lot.