Rear trunk rust repair

[stratoblaster]

I want to weld a new rear trunk in. I have the typical rear-trunk-taillights rust. I am new to welding but I have MIG and I am not afraid to use it! However, I know I can't just run a weld along the whole patch without alot of warpage, so how do I do this? Can I just make enough tacks to be sure it is secure then seam seal it? I mean, the whole perimeter of the patch panel doesn't have to be welded does it?

[psu914]

I always weld the entire perimeter of the panel, a lot of people however just spot the panel and seal around it. It all depends on how comfortable you are with welding. I find that it is better to do the entire panel and not risk rust forming in the seam. If you make sure that there is no rust where the panels meet and do a good job sealing it, it should be fine. To avoid warping when doing the entire panel, i spot the perimeter and then fill in between the spots, i use a wet spong to keep the panel cool and move around the panel doing opposite sides so that any one spot doesn't get to hot.

[stratoblaster]

So... When you cut out the old trunk, I assume you leave a lip where possible? Maybe 0.25 inch or so?

[Biggy72]

well with mine I just cut out a piece of metal that would fit in the hole that was there, and that just made for a clean transition from one metal to another. If you could I guess you could bend a lip onto one of the pieces, but I don't know how much of the trunk you're going to replace, if not all of it. I'm not a pro by any means at this though, I haven't even graduated highschool yet.

[sean_V8_914]

the proper technique is called stitch weld. never stay too long in one area. heat build up in the area expands the metal, causing the warpage as it cools and contracts. center the panel, then tack it in the center. Then go to a far corner and "stitch weld about 1-3 inches. go to the opposite side and weld there...connect the dots alternating sides. This allows both sheet metal and welder temps to stay low. The factory did not weld the entire panel. I only weld the full seam if it is load bearing.

[Biggy72]

ya what he said