The Stovebolt Site Forums The Shop Area General Truck Talk structual integrity of frame?

I'm not doubting GM's engineering, I'm doubting mine.

Preping the frame for sandblasting and paint. Found an area that the PO had violated, large hole (looked like from a torch), rusted to paper thin, deformed metal.

I decided to cut out the problem area and replace with the same thickness metal.

That was accomplished fairly easily.

Here is my worry. The picture show it better, but the patch work was done right at the front crossmember on passenger side. Thus, I'm worried about the integrity of my patch, forces from the engine and leaf spring hangers.

Becasue of the crossmember I cant weld the entire inside of the patch. Now I am pondering adding in fisher plates to help distribute the load of the "cut then welded area"

But I really dont want to add the plates for cosmetic reasons.

What do yall think?

material removed is in my hand:
http://i377.photobucket.com/albums/oo216/texaslocogringo/54%203100/Work/IMG_0398.jpg

patch:
http://i377.photobucket.com/albums/oo216/texaslocogringo/54%203100/Work/IMG_0401.jpg

after grinding:
http://i377.photobucket.com/albums/oo216/texaslocogringo/54%203100/Work/IMG_0403.jpg


Thanks a Bunch
-LGringo

If you got good penetration on the weld, I think you are good to go. Unless you plan to go rock crawling - you should be fine.

I had to replace some of my frame because of rusted out areas ,check it out on frame restore on my photo bucket, I agree if you got good weld you should be fine ,the only section of the frame I could save was the top section I had to patch in a new side and bottom about 10 inchs long and I drove about 4000 miles this year and have had no problems.


Pete

Pictures from the backside would tell you more than those you took from the front.
Chuck

I am a CWI (Certified Welding Inspector) so I will offer up my 2 cents. I would be worried if I looked from the back and didn't see any penetration. If that's the case grind out the weld in sections and reweld them. For no longer than it will take it's worth the piece of mind of not worrying about.

Tips:

1.0 Whenever welding with mig on metal heavier than sheet metal you always want to leave a gap for good penetration. It's also good to bevel weld prep the edges.

2.0 When doing a flush patch it's always better to drill large holes in the corners then cut out the piece. Or torch cut the corners as radii. These nice generous radiuses reduces the stresses considerably. Square corners can become cracks, and often times do on structural members such as frames that are subject to cyclic loading.

I hope this helps, and good luck!

thanks for the input guys.



my thoughts exactly, the roughest thing this truck will see is MAYBE a speed bump.



I'm away from the truck for a bout a week so pics would have to wait. But I did look when I was doing the patch and the welds did have good penetration. I had a very small gap all the way around the patch so that the weld could sink in good.

Also, you must remember that frames have their strength in the flanges, not the web. I think you will be fine.

In respect to the trucks ability to carry weight (verticle loads) the structural strength of the frame is overwhelmingly based on the web, not the flanges.

I agree with Crenwelge. Under vertical load/"payload," the upper flange is in compression and the lower flange is in tension. Somewhere between the compression and tension, the stress is neutral/zero. This is in the web.

The web serves to keep the flanges apart, WRT vertical load. Flanges carry the vertical loads. Webs carry transverse loads.

Bill

Hot Rod John, I have been running over the road trucks for 47 years and my shop has been doing frame work for over 40 years. I guess now I am to find out that I didn't learn even the basics of frame work in all these years.

One of the things you could have done would be to make the original cut out section of the frame on an angle instead of 90 degrees, then I would have put an inner piece of plate shaped lie a arrow front and back and welded it on the inside of the frame. the angles keep the forces from hitting the weld along a seam directly.
Kieth It looks nice though.....