Rust repair consult, please.

Need a quick consult. This is on the e21 project, on the rear windowsill (by far the worst rust on the entire car). This car isn't gonna be a show car, but it's also not going to be a Chumpcar, so I want to do a repair that will last some time and look good once painted.

Keep in mind I am pretty "novice" at welding, but this is a car I plan to do some learning on if needed.

So here it is all cleaned up. Very pitted with several small holes.The other side wasn't nearly as bad and was able to clean it up and build it up with filler primer and it looks good. But it didn't have all the holes and much shallower pitting.

So how do I attack this? Cut out just the flat area and replace with a flat piece of sheetmetal and hopefully be able to blend it into the beveled edge going down? Or do I clean, fill, and build it up? Any thoughts welcome, preferably something you think is within my ability considering my limited welding skill/experience.

POR-15?

Window mounting areas are the hardest to fix, personally, I would just naval jelly, prime, and bondo it.

Knurled wrote: POR-15?

That's what I used on the other side, thought I'm a bit hesitant since a lot of paint doesn't stick well to POR-15. This side I have do deal with the holes though.

I'd at least try to weld up the holes, possibly by using a copper block, before filling in the rust scars.

Panel bond, 3M 08115. Great stuff for repairing window channels where metal is too thin to weld easily and no risk of catching interior bits on fire. After rust removal you can bond patches in and fill small holes/pits. Then sand, prep for filler, paint, etc.

BoxheadTim wrote: I'd at least try to weld up the holes, possibly by using a copper block, before filling in the rust scars.

can you expand on using a copper block. I've heard "of" it before but that's about it? Do you just use the copper as a backing piece to fill the hole, since the weld won't stick to it?

When you use POR15 are you using the precoat stuff too? I would be temped to just coat it, bondo it, and paint. You are going to have imperfections if you cut and weld in patches that will need that too. It is a flat section at least if you do cut and weld patches, just remember tack move a couple inches tack and so on. Keep a wet rag around to cool the metal down with from time to time also (be careful of steam)

jere wrote: When you use POR15 are you using the precoat stuff too? I would be temped to just coat it, bondo it, and paint. You are going to have imperfections if you cut and weld in patches that will need that too. It is a flat section at least if you do cut and weld patches, just remember tack move a couple inches tack and so on. Keep a wet rag around to cool the metal down with from time to time also (be careful of steam)

I need to get some. I wasn't aware of it, having only previously used POR15 for chassis stuff that didn't need painting. Guess I should order some though.

I am using the Metal-Ready prep though.

irish44j wrote:

BoxheadTim wrote: I'd at least try to weld up the holes, possibly by using a copper block, before filling in the rust scars.

can you expand on using a copper block. I've heard "of" it before but that's about it? Do you just use the copper as a backing piece to fill the hole, since the weld won't stick to it?

Yes, that's pretty much it. Hold the piece of copper underneath, then plug the hole with weld. I'd clamp it underneath rather than holding it, though...

BoxheadTim wrote:

irish44j wrote:

BoxheadTim wrote: I'd at least try to weld up the holes, possibly by using a copper block, before filling in the rust scars.

can you expand on using a copper block. I've heard "of" it before but that's about it? Do you just use the copper as a backing piece to fill the hole, since the weld won't stick to it?

Yes, that's pretty much it. Hold the piece of copper underneath, then plug the hole with weld. I'd clamp it underneath rather than holding it, though...

rgr that. it's a tough place to get a clamp since there's a 6" inner lip there. I've heard that rare earth magnets might work though, so I might try to find some of those locally.

If you have good welding gloves and a block of copper, you might be able to hold the block instead of clamping it.

My welding gloves were never that good .

In reply to irish44j:

Those magnets are super cheap on ebay. They do make magnets for welding though. They don't work when they get hot but for sheet metal work they work fine.

You could possibly put lead on it and fill the holes and make it smooth.

Oh there are butt weld clamps too, $8 for and 8 pk at HFT

Buy a copper welding "spoon" at Harbor Freight. It has a nice chunk of copper mounted to a handle. Pretty easy to hold it against the spot you want to weld.

http://search.eastwood.com/search?w=copper

DeadSkunk wrote: Buy a copper welding "spoon" at Harbor Freight. It has a nice chunk of copper mounted to a handle. Pretty easy to hold it against the spot you want to weld.

yep, went to HF today and picked up one. Perfect. Or so we'll see about it this evening :)

It's a flat area with 90* bends. That's pretty straightforward to cut out and replace with good metal - leave the corner gussets and try to keep an 1/8" or so of the flat. All that pitting looks really thin. Trying to fill them - you'll probably get a good feel for your welder after blowing out a few big holes.

Alternatively, this might be a good place for some of the metal-based fillers

well, I did the one hole on the driver's side. The copper spatula didn't fit perfectly in the gap due to a panel below, but here's how it came out....

feels very solid now. I poked at it hard with a pick just to see and all seems good. The imperfections I should be able to just build up smooth.

Thoughts before I attack the other side that has more?

before:

after:

underside as well as I can take a pic there

so here it is all finished up. Used filler primer only to build it up and smooth it, plus some wet sanding. No bondo or filler. Came out pretty good I think :)

nicely done sir.

Indeed, well done!

thanks. I know this stuff is child's play for many people here, but after working on cars for 20+ years and never learning how to weld/rust repair correctly it feels like a massive accomplishment from this end, lol.

The other side is worse. I welded up about 10 holes/thin areas last night and spent forever grinding. Hopefully it will turn out just as good.

Nice!

Now that you are a professional body man, I've got a little rust on the 635...