Hey guys wanted to know your opinion on my cracked frame. Either way im going to weld it to see if it holds if not going to swap in an f250 frame. This is a f150 4x4 frame. Crack is behind engine crossmember on passenger side. Not the best pic will take a better one tomorrow.




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That's a beauty.. Looks like there a hole in it where it rusted through. Put a re-enforcement plate on the back side if and weld it up.

 

Weld then plate then good to go.

 

Wow rusted a hole too. I would cut a plate that fits perfectly inside that section of the frame and weld the edges, and do the same if possible on the backside.

 

Check the rest of the frame, there may be a lot more about to break.
I would probably fit a plate on the inside, clamp it tight and weld it, at the top and bottom, and have it a few inches longer then the cracked section, basically copy the vertical part of the frame, and weld where it meets the horizontal.
Then I would trace out the cracks with a grinding wheel, cutting completely through the original frame to the surface of the plate inside.
Then weld the edges of you cut out cracks to the new plate. I would prefer a gas type mig welder for this, or 7018 rods and a DC arc welder,or 6011 on AC. Flux mig would work but I
am not good at it.
3/16" or even 1/8" mild steel would be fine for plates, the stock frame is just a cheap mild steel, no voodoo alloy or heat treating.

 

Thats the only crack in the frame, it happaned last summer when i was pretty hard on it in a mud pit. Had the idea i could climb a 10 foot bank with stock suspension. Almost made it too

 

Might have cracked my frame again on my 95. I jumped a snow bank with it today. Lol

 

Heres some more pics of the frame. This truck is my daily driver.

 

Years ago we used to do dirt track cars & would sometimes have this issue after pulling a frame back straight or when the track was overly rough. Everything Scraptor said was good. To fix it best do the following

#1 would be clean the rust off & make it shiny all the way around the plate.
#2 Weld up the crack on both sides. You want the weld to penetrate about 2/3 the way though on each weld. Tooo much penetration & you can have burn through. Stitch weld this in short bursts jumping around to not overheat the frame.
#3 let air cool to not quench the metal. Quenching will make it more brittle.
#4 cut out a fishplate for each side. Inside & outside of the frame. The fishplate should look the the open mouth profile of a big mouth bass on each end. This gives you the most weld area & disperses the weld area for the strongest joint.
#5 Place the cut out fishplates over the weld & stitch weld in short burst jumping around to not overheat the metal.
#6 Again do not quench let air cool.
#7 After cool clean the rest of the frame & then paint with por15.
#8 for additional strength you can box the frame the prevent further cracking.

 

I went through this same problem last year.


You have two options.

The first is just realign everything back to straight and plate it with some thick stock (1/4" or so) after thoroughly cleaning everything. Unfortunately this has no guarantee of holding. But it certainly is a quick fix without disturbing much else.

A second option is to totally replace the crossmember with a fresh one and beef it up before you install. Its a lot more work but ensures you have everything tidied up. If you have the space, time, and patience its well worth it IMO. You also get to replace all those worn out sqeaky rivets with some good grade 8 hardware, allowing you to remove/replace with ease if it ever happens again.



I would also highly recommend checking the frame at the steering rack, these are also prone to failure. Double plating this with a spare frame works great!