[Blazin_Jason]

Hey guys looking for some input and help on the way to repair some rust on my DD. Not having experience here is what I am planning on doing and please let me know otherwise. In front of the tire I am thinking of replacing the entire area with the patch panel. Cut along the top, probably have to drill/grind out some plug welds inside the door jamb, and cut it along the bottom. Then weld in the new piece with a couple plug welds in the jamb and seam sealer afterwards, and butt weld the rest of it in. Or is there an easier/better way to do that? Or should I only do a little more than the rotten areas? I understand to tack it in and let it cool and do that slowly as to not warp anything. Is it better to butt weld, or can I lay the seam under the body slightly and weld there, then use a little more body filler. After cutting the sections out, what should I apply on the backside of the panel and inside the rotted areas to help seal it better? Understand that I am trying to get it to last and look good while learning to do it myself. Thanks for any input.

Here is before I hit it quickly with a wire wheel to see what it was really like.


P.S. The body moldings will be removed so I can't hide a seam under them afterwards

 

[sunsetdart]

Best thing to do is to cut back to good metal. No sense cutting all the way to the jamb on that side. The back quarter, I would do the same, cut where the metal is still good and patch from there. That way you have good metal to weld to. I would make a cardboard template in all cases and then cut your sheetmetal (20ga) to weld . I also would butt weld the patches, welding every 3 inches till you get the entire panel welded. Just be careful to not warp the metal.
To protect the backside, I would use a good rust inhibitor then coat with a good rubberized undercoating to seal.

 

[Blazin_Jason]

Thanks for the response. Since I can't seal it up afterwards I have been considering panel adhesive. I'm still on the fence but I think it might be a lot faster and easier. I would get an air flange tool and lap the joint underneath.

 

[skostur79]

with my prev repairs with panel adhesive

there will be a ghost line were the two were joined

even with filler on top

but does seal up the metal to prevent corrosion

 

[Blazin_Jason]

I've read that. Since I won't be painting the vehicle now I wonder if it will all cure by then (6+ months)? I'm leaning towards the Norton Speedgrip. It says to epoxy prime first before applying polyester filler. If it ghosts then maybe I can seal it up before painting. That was my thoughts anyways.

 

[Lost in NJ]

Contrary to popular belief, you will be warping the panel as you weld no matter how 'cool' you keep the metal.

Every weld is a shrink point. Lots of little spots welds limits the heat you put in to the metal and limits the warpage. The effects of warpage are not always clear and are dependent on the shape of the panel. Some times the effects may show up at the opposite end of the panel with a poor door gap fit!

You correct the shrinkage by doing hammer on dolly work to stretch the metal. This is kind of hard to do if you overlap the metal at the seam. Butt welds are not hard to do.

You need to be sure every weld has full penetration. The most common mistake is to not have full penetration. You need to practice on the same gauge metal.

You must make the cut in to the good metal. You will only ask for grief to make welds across a rusty section. Keep in mind 2" or 6" of patch is the same amount of work.

Copper is your friend. If you back the weld with copper you reduce your change for burn through. You also make a burn through easier to fix. If you have a large area to fill get a regular tig rod the composition as your wire. Put the rod in the hole and start the arc on the rod. Feed in the rod to control the heat and speed up the fill.

Use a flap disk to grind down the welds. Do a bunch of welds (1/4" or so ) and then go back grind them down and do hammer on dolly work to correct the shrinkage. Then repeat until welded.

If you want to learn how to high quality patches as you go I suggest you rent some videos from Smartflix.com. Learning about metal shrinking and patch panel install by watching the pros can make a great difference in your outcome.

 

[kenseth17]

Thats pretty much how I did it patching an old mustang. Enough of the bottom was gone, and believe part of the jamb and wheelwell areas, that it made the most sense to me to just replace the whole bottom section, folding the edges over and spotting in in the wheelwell and jamb, and only having one weld seam. Treated the backside of the patch, and between where it overlapped in the jamb and wheel well. and butt welded it in. Interior was removed, and I got behind and treated the backside of the patch afterwards. Seam sealed the overlaps. I prefer butt welding because it makes it easier to properly treat, and you don't have overlapping metal, which always can be a problem area. Pics are of opposite sides of car, but both sides were bad.

 

[Blazin_Jason]

I did one and it turned out ok. Coating the backside is almost impossible as there aren't any holes on the inside. I think I am going to go panel adhesive on the other side and areas where I can't paint the welds easily afterwards. Anyone know what a body shop does for these type of repairs?

 

[purespl]

They use weld through primer on both sides of the metal to protect against corrosion after welding