How would you fix this crack?

[stutaeng]

I totally get what your saying about liability but nothing on a Gmt 400 frame is heat treated. Mild steel. It's later model stuff you have to worry about different alloys such as HSS, SHSS and Hydro-formed frame sections. I'm not so sure those are considered heat treated either but there are very specific guidelines on where and how to repair those type of frames. Unless your doing a tail section at the factory joints most times you throw those later model frames away.

I was going to say the same thing...I don't think these frames are heat treated...(why would they heat treat, it's an expensive process.)

Do you know what grade of mild steel these are BTW?

I'm into building design and I don't recall ANY structural grade of steel being heat treated, even high strength grades ones. Maybe some specialized steel part are heat treated to increase abrasion resistance, but I can't think of any other use in my industry.

 

[PlayingWithTBI]

I don't recall ANY structural grade of steel being heat treated, even high strength grades ones

I had a tool and die maker working for me in a previous life. He used tool steel like A-2 or 4140 which had to be heat treated after machining, we had a little oven for that. For our extrusion dies we used H-13 tool steel and nitrided them in a big oven using NH3 (anhydrous ammonia). Some ovens used a burner to eliminate the excess hydrogen, others used a scrubber. That process really stunk with all the ammonia floating around - had the ovens outside, ha ha.

 

[Hipster]

I was going to say the same thing...I don't think these frames are heat treated...(why would they heat treat, it's an expensive process.)

Do you know what grade of mild steel these are BTW?

I'm into building design and I don't recall ANY structural grade of steel being heat treated, even high strength grades ones. Maybe some specialized steel part are heat treated to increase abrasion resistance, but I can't think of any other use in my industry.

I'm not sure on the technical call out on what steel it is constructed of. Maybe 1014/18 like some mild steels that are used for structural compponents?

I know with newer vehicles I'm repairing I can look up on CCC for proper repair guidelines and it will specify where or if there are Hss steel etc. sections and "if" there are sectioning guidelines to repair those areas.

 

[Brian Shanahan]

There isnt anything left to weld to on that crack. You cant weld rust.
Take a wire wheel and a grinder to that entire area inside and out fore and aft for several inches and clean it all back to solid metal.
I can see that crack is already splitting up towards the top of the frame.
I would try to get a couple of feet of good junkyard frame if you can find one.
But that also depends on your level of welding experiance.
If you do try it yourself, dont buy a cheap harbor freight flux welder.
Make sure you are actually bying a MIG welder with shieldind gas capability.
The "Easy Mig" or whatever they call it these days is not an actual MIG
That wont work.
The frame is thick enough to stick weld.
If you know how to stick thin ****.
MIG would be much easier
But you also may have no choice.
Up here the welding lawyer chickenshits wont touch that because of "liability"
Whatever you do, practice on some scrap of the same thickness first.
Watch some vids, do some reading etc.
You can do it. Its just gonna take some fuckups before you get it.
And, if you get this figured out, you will happy as hell that you did when you start the sheetmetal.
That is another level of difficult but at least you will know that

Nothing wrong with flux core wire feed. It’s actually designed to weld hotter and get more penetration then shielded gas migs. But no matter what without clean surfaced area to weld and the correct support in this case I’d use a box tube to match the frame height for support adding length from the middle out centering the crack and weld all open contact area inside the frame to the box tube. Including the whole crack. Using a plate will only bandaid it and it will crack in the same spot with the load pressure that caused the crack in the first place. From my experience fix the issue causing the crack before fixing the crack. Rust don’t cause cracks. Pressure points do if not correctly supported do.

 

[Hipster]

Nothing wrong with flux core wire feed. It’s actually designed to weld hotter and get more penetration then shielded gas migs. But no matter what without clean surfaced area to weld and the correct support in this case I’d use a box tube to match the frame height for support adding length from the middle out centering the crack and weld all open contact area inside the frame to the box tube. Including the whole crack. Using a plate will only bandaid it and it will crack in the same spot with the load pressure that caused the crack in the first place. From my experience fix the issue causing the crack before fixing the crack. Rust don’t cause cracks. Pressure points do if not correctly supported do.

Flex is why you shouldn't put a piece of box tubing in it. That would move where the frame flexes and it could possibly crack somewhere else.

No need to totally overcomplicate this, fixture the truck to close the gap up, clean the metal, drill stop the crack, weld the crack, weld a fish plate of the same thickness material over it, and it's done. Restore the original strength is as far as you have to go.

ER70s-6 Mig wire has some properties that lends itself to less than stellar clean and polished metal that's short of sandblasting. This should be done with .030/.035 wire. Flux core is prone to more weld inclusions which is not what you want here.

A 140a welder is marginal at best. A 90a flux core will never get it done properly. You don't want to "cold" weld this.

 

[E-gads]

I think Hipster summed it up pretty well but I thought I'd add my two cents worth. I've been welding and training welders for almost 30 years. There's a lot of BS in the world of welding that is not backed by any science or testing. If I had a nickel for everytime a welder has told me "It'll hold" while looking at a crappy weld, I'd be a rich man. Since the frame is flexing constantly you need to be worried about two things. One, stopping that crack. Cracks can propagate quickly through steel that is flexing and or vibrating. Drilling a hole at the end of it will stop it as long as you get the end of it. which is usually past the end that you can see (that's why we have mag particle testing). The second thing is to not create stress concentrations with your repair. Putting a rectangular doubler over the repair will create stress concentrations perpendicular to the bending moment on the frame at the toe of the two end welds. To get around this you need to taper the ends of the flatbar (think a rectangle with a rounded triangle on each end). If you want to box it in with a piece of flatbar you need to do something similar with the ends I am not saying you should or should not box it in, that is up to you. I will try to add a picture. To sum it up, I would repair it by grinding all the rust out, drilling a hole at the end of the crack, maybe a half inch hole to make sure you get the crack, vee out the length of the crack and weld it. If you don't vee out the crack, you might as well not even weld it because it will fail. You might need to put a small backing plate behind it so you don't burn through. Then I would put a doubler plate over the top, making sure that it terminates on good solid steel on both ends. This is not rocket science but it does require that you be fastidious about cleaning the parent material and getting good penetrating welds. I would probably go past the first trany support bolt and re-drill that hole. Like Hipster said, I would use material the same or similar thickness of the frame. A36 steel is fine. This is like painting, it's all about the prep. I would probably pay someone to do it. This is out of position welding and is more challenging to do . Especially for a beginner. I wish you the best on this repair.

 

[thinger2]

Ut

Nothing wrong with flux core wire feed. It’s actually designed to weld hotter and get more penetration then shielded gas migs. But no matter what without clean surfaced area to weld and the correct support in this case I’d use a box tube to match the frame height for support adding length from the middle out centering the crack and weld all open contact area inside the frame to the box tube. Including the whole crack. Using a plate will only bandaid it and it will crack in the same spot with the load pressure that caused the crack in the first place. From my experience fix the issue causing the crack before fixing the crack. Rust don’t cause cracks. Pressure points do if not correctly supported do.

Absolute and unbelievable ********.
Are you actually telling this guy that flux welding that frame is okay?
Are you just trying to kill him?
In no ******* world is that a flux weldable frame.
The very ******* notion that you could even attempt that weld with a Harbor Freight A/C positive electorde with the arc reforming at 60 hertz is is not only unimformed ******* nonsense but you have put yourself forward as some type of an expert when you clearly dont know **** all.
Did you just pop up after some Google?
I am a certified welding inspector and a certified aviation inspector and I aint **** compared to 6g Kenny.
So you, trying to tell this guy all about how to do it with your sudden found welding knowlege?
Get ******.
Are you gonna get off when you kill this guy you ****?

 

[Raspi454]

Oh Lord
I'm having someone do it professionally already talked with him, it'll be a few weeks

 

[Hipster]

Oh Lord
I'm having someone do it professionally already talked with him, it'll be a few weeks

Did he mention a bernzomatic propane torch and a stick of dynamite? Because I think everything else has been covered, LOL