Frame welding

[mana333]

Hi guys,

This is a nice little site. I've been lurking for about three days now. Very educational.

I have a Chevy Tahoe I bought on the cheap because it had some frame damage. What it looks like happend was that the upper shock mount tore off a chunk of the frame. Below are some pictures of the damage. I've taken it to three mechanics and all of them said they couldn't help for one reason or another. Which, is fine by me. It gives me a reason to take up welding.....

How would you go about patching this up? The guy I bought the car from cut out a section of a frame from another tahoe. Apparently, the other side's upper shock mount was reinforced, too. It looks like some one laid a braket on top of the frame and proceeded to melt globs of steel on top and around the bracket.

Any pointers appreciated.

Mike.

 

[malcolm]

Theres a lot of force at the top of shock mounts, so the welding and repair would have to be good to give it a chance of lasting. What is it supposed to look like? Could you post a picture of the other side.

I'd probably start by repairing or boxing in the chasisis rail, probably by overlapping a new section, then make a new mount for the shock

Though if you have a replacement part of frame maybe cut it down and seam weld it to the existing frame - cut the repair and the old frame so the edges fit against each other all the way around, butt weld the parts together, then weld a further strengthening plate across the join.

You'd need a welder capable of about 150 amps if that is 1/8 inch sheet. MIG would be the most easy to learn, but you'd need to practice a lot on similar thickness sheet to get a good technique before starting on the chassis - a load of force goes through those shock mounts.

 

[mana333]

Thanks Malcolm.

I was thinking along the same lines, however I was thinking about putting a strengthening or beef up plate across the front and the back. On the front, I don't know if the A-arm mounts would get in the way of laying the strengthening plate. Of course, on the backside it would only get welded at the opening. Do you think this poses integrity issues?

Also, do you think a Clarke 130EN will be able to handle it? I used your calculator and it said that it would handle 1/8th or .125 inch steel in the middle of the highest setting. Unfortunately, I already committed to buy (should be here end of week). I already picked up some steel at my neighborhood Lowe's and am ready to start practicing.

Here's some pictures of the other side. As you can see, they covered the cross member hole. It also looks like they used some puddle joints (learning the lingo ). After looking at it again, it looks like they made a new frame section to go right over the existing frame. Included is a picture of the piece he sent me.

Thanks,
Mike.

 

[shenion]

A Clarke 130 will be a bit weak to do the welds in one pass. If you can weld both sides it would do fine.

I would probably build a "U" out of angle iron for the top, then notch around the frame. Then add more angle iron vertically to the front of the frame. I usually have a bunch of anlge iron around

 

[mana333]

Hmm, well that sucks. I went back to the buyers guide and it says right under the chart that 150 or more for land rovers. I totally overlooked that. I'm guessing a Chevy Tahoe is a rover equivalent.

Well, considering that Malcolm had 3mm listed for the max and 1/8" is roughly 3.2mm, I thought it would be in the neighborhood with a good cleaning and such. I guess I'll practice on 1/8th with it and if I don't feel confident, I'll sell it and buy a bigger one.

As far as using angle iron and bending metal to fit, I'm not quite sure I understand. You'd weld two angle iron pieces to form a "U" or would it look more like a "|_|"? And how would you get the the angle iron on the front to be flush (or close to flush) with the frame? Or are you talking about shaping the iron? I think shaping metal was a bit beyond what I wanted to learn for this project unless it's absolutely necessary.

 

[shenion]

I would not worry about being flush with front of frame. There should be room, if not that is what angle grinders are for.

Frame is shown in red. Support would be applied on top of frame. I would probably fill in the center of the "U" channel for strength.

 

[mana333]

Interesting. Thanks for taking the time to do that up! I'm not sure I'd want to go straight into that game plan as I want boths side to at least have a symmetric semblance. However, if I mess up the replacement part, I may use a modified version of that as a plan 'B'.

I suppose if I really mess things up, I could have the top welded '|_|' sticking out far enough to serve as the bracket itself. Do you think drilling a hole in the middle of the weld for the shock would pose integrity issues? Perhaps I can weld beef up plates on the top and bottom of the hole.

Thanks for the input!

Mike.

 

[shenion]

Looking at your picts, it looks like you will also need to fill in the area ripped out of the frame. That would probably be the most difficult part.

As for symmetry, if one side has broken off, I would redo the other side anyway. Or just stop 4WD'ing the Tahoe

You can add another angle-iron to the top to double up. Might make welding the fender well to it easier.

As far as worrying about weakening it be drilling through the weld. A proper weld is stronger than the mild steel. You would probably have to weld both sides with the 130EN.

 

[mana333]

Update

Just an update to show the progress.

Originally, I thought the welding would be the hardest part... not so much. What was really the pain in the butt was getting the piece to fit on the frame. After the initial cut, it took three days grinding for it to sit right on the frame (Keep in mind I'm in the middle of finals week at school, so time was sparse for me). I have the smell of grinded metal stuck in my nose.

I was a little apprehensive of using the 130EN to do the weld. I did some practice butt joints on some fresh metal. After going to town with a hammer on them, they would bend instead of break, so I thought that was sufficient. And yes, doing vertical and horizontal welds was a little trickier then standing over them and doing them (the way I practiced...).

These pictures are of the cut in the frame, the initial cut on the part, and the semi-done welded part on the frame. No, the welds aren't pretty. I had to overcome some gaps so in some places they are really horrendous.... but hey, it's stuck. I plan to grind the welds back down and redo them. Anyways, thanks to Malcolm and this forum for all the knowledge and giving me the confidence to actually attempt to do this.

 

[shenion]

Doesn't look bad. The camera seems to hide the actual weld and highlight the spatter.

That type of work is hard to see. The left looks difficult as you are welding in a channel almost blind.

With the 130, keep the arc length real short and torch near perpendicular to the surface, you can get a bit more penetration from it. I also place one hand on the work (usually make a fist) and rest the torch hand on it. Allows smooth control.

The right side looks good from what I can make out. I would redo the bottom. The bottom is probably where it will try to pull out. I would use a cut of wheel and grind a slot down the entire weld. Then weld using a zig-zag motion spanning the grove. That should give you full penetration on the weld. Weld will be a bit wide, but strong.