Split rear crossmember

K

keeeef

Member
Found these cracks/splits in the rear crossmember on my 36 pickup today after removing u bolts. Any advice on repairing please.
 

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v the cracks,weld, gring smooth and make a plate of 3/16 steel plate, locate and drill holes and weld it in place
 
I don't think you can plate either side to strengthen this area. The spring is a tight fit on the inside and the u bolts are a tight fit on the outside. Deep Vee it, weld it, clean it up and move on to the next thing. Or did you mean plate the bottom of the flange? That might work, as long as the u-bolts can still clamp the spring.

Mart.
 
Before you commence welding find the end of the crack and drill a hole there, this will prevent the crack from growing as you apply heat through the welding process.

Then again, this piece of metal is showing extreme signs of metal fatigue, I'd be looking for another, or removing it from the Chassis, repairing then Normalising the Crossmember.
 
Use stick, 7018 rod... Or tig- I don't know what fill to recommend...

I didn't want to remove my (very)cracked front crossmember.

I repaired my front crossmember with 7018, found a piece of square tube the correct thickness to cut doner material from- for the radius at the edges- made all the welds by putting the frame on end or what ever it took so as not to have to do vertical welds...
This was on a bare frame, leaned against house- stood on the roof to weld.

I reasoned that by adding in new material I could be away from areas that broke.

Don't use mig

Karl
 
Karl Wolf said:
Use stick, 7018 rod... Or tig- I don't know what fill to recommend...

I didn't want to remove my (very)cracked front crossmember.

I repaired my front crossmember with 7018, found a piece of square tube the correct thickness to cut doner material from- for the radius at the edges- made all the welds by putting the frame on end or what ever it took so as not to have to do vertical welds...
This was on a bare frame, leaned against house- stood on the roof to weld.

I reasoned that by adding in new material I could be away from areas that broke.

Don't use mig

Karl
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I too have repaired cracked and at times "broken out" cross members with NO subsequent issues at all. I grind away the cracked area until I am in GOOD / SOLID material. When there are pieces missing, I use a piece of steel the exact thickness, customized it to fit the requisite area to be repaired. I TIG... no problem.
I would dare anyone to find any of my repairs. Welded correctly, it will be stronger than ever required.
I am not certain how normalizing would have any benefit to very low carbon steel. I would however, advise to allow the areas to cool naturally. That is, do not apply water, etc. to speed the cooling process.
 
scooder said:
Karl, why not use mig?
Martin.
Click to expand...
I guess that since I learned on stick, I may be speaking with a bit of a slant...

I get better penetration with arc... or tig. I have heard that mig wire is hard, and I think it may not blend in well, When the mig starts, it's cold, and some of the welds I've autopsied don't seem very strong. The 7018 rod is supposed to be a high strength steel. I like the way it goes down.

I suppose that since almost nothing I know about welding comes from a book, I should be a bit embarrassed by your question, but I do stand by my opinions.

Karl
 
Karl
7018
Even number is DC
70 is the tensile strength of the rod. 70,000 pounds
1 is all position.
8 is the iron powder flux which makes such a pretty weld.
Low Hydrogen rod enabled many people to weld.

Bruce

Works good
Lasts long time
 
karl, your right mig wire is hard, but there is a soft mig wire made, its for auto body work, most places dont carry it or even know about it, you have to ask for it and have the suppy company order it for you,its expensive, i will try and get the numbers for that wire
 
I would also TIG weld it like Kube. MIG wire does come in various hardness and there is something called dual shield that is VERY strong. Like any welding, you have to use the correct wire/stick/filler material for the job. For bodywork, there is MIG wire called "easy grind" that is S2 I believe. S6 is the hard wire usually supplied with wire machines.
 
I am not certain how normalizing would have any benefit to very low carbon steel. I would however, advise to allow the areas to cool naturally. That is, do not apply water, etc. to speed the cooling process.
I do not know the type of steel used in Ford Chassis' but a low carbon steel would make sense, but not a very low carbon steel. A low carbon steel would aid in the stamping of the chassis rails but consideration must also be given as to how the steel will function in service.

Normalising will help any metal part (than will accept the process) that has been subjected to stress, to become normal again. In this application the Crossmember will not just accumulate stress from the repair process, but has already aquired stress from its life in service. Perhaps I should have used the general term Stress Relieving (which includes Normalising and Annealing) rather than being specific.

And then again it's easy for a guy who has access to Furnaces and Heat Treatment equipment to blithely say '...and when you're finished welding, just pop that part in the Furnace for a few minutes'. I forget that sometimes a procedure I wouldn't think twice about doing, is for someone else a big problem. Then again, information is a good thing, if enough of it is put about, often good decisions are made.
Click to expand...
 
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Karl, thank you for your explanation of your opinion. I use mig almost exclusively for chassis and body repair. Done right with the right stick/wire is good and will do the job properly and safely. The one Big issue I have with mig, is that it easy to lay a weld that to the inexperienced eye, looks good. It's almost to easy, if you catch my drift, this I believe is where it gets a bad rep re strength and penetration. Done right, it's perfectly good for the job.
Martin.
 
Thanks guys

I only have a mig so will try and find the right wire for the job here in the UK. If not will try and find someone local to weld it for me but prefer to do it myself if possibel.

Cheers
Keith
 
ER70S-6 mig wire is the replacement for the 7018 rod. That is what i use for most of the automotive steel welding i do.
 
That steel probably has porosity in it and is the reason it cracked. If i remember correctly to get rid of this you need to heat it to *400 and keep it at that temperature for 1 hour per inch of steel which would be about 7.5 minutes for that thickness. A welder supply will have temperature pencils you can buy for *400. When you reach *400 it will melt. V it out then and weld it,. grind it smooth to stress relieve it and you are in business. I hope this helps.
 
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