Door Rust Repair (Amateur Hour)

Zak99b5

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Albany NY
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2003 Jetta TDI
I was going just to replace the door with a good one from a wrecker, but I figured why not try to repair the rust myself—even if only to get a little experience.

I pulled off the rub strip. Found a second rust spot hiding near the rear edge of the door underneath as well.



I used one of those plasticky rust and paint remover wheels, then a wire wheel.



My first mix of Bondo I used too much hardener. Began to set as I was spreading the filler on. While it was still crumbly I scraped off most of it.


Second batch I used less hardener, and it went on much better.


I sanded it down with 320 and 600. It’s nowhere near perfect, but my goal is to keep the car looking presentable. Plus it’s low on the door, on the side I don’t normally see.


No Bondo on the rear spot since the rub strip will cover it.

Done for today at this point. I’ll do some more sanding tomorrow, and then another coat of primer.

Im happy enough with it, since it’s better than the rust bubbling up. I know, I know, it will bubble back up in a couple years.

Id appreciate any pointers on the painting to finish this. Plan is to do the whole bottom section, cover the primer above, and try to blend it. Then clear to the whole door to the bottom of the windows.
 

snakeye

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Dec 13, 2009
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Montreal, Canada
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2003 Jetta and Wagon, GLS 5sp
Just scuff a large surrounding area with 1000 grit and overlap the paint. I've used a blending solvent with good results in the past on both the base and the clear coat. Didn't need to spray the whole panel, just the area that was bein repaired.
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
imo get some fiberglass bondo behind all that from inside the door card. otherwise not too shabby! a bit more work to it and it would disappear!
 

Zak99b5

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Albany NY
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2003 Jetta TDI
I'll be using rattle cans of mixed by paint code base and 2k clear, so I can't mix anything with the paint. Amateur hour, remember lol.

Thst said, I've seen the folded over paper masking technique. I know that will work with the base (tho maybe unnecessary), but could I do that with the clear? Instead of going all the way to the window rubber.
 

Zak99b5

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2003 Jetta TDI
Sanded a bit more, then tried to blend the base with the rolled paper masking trick.

Then I cleared the whole bottom portion of the door. Used the rolled paper again at the rear edge, since I just went up to the window line.

Pics to follow.
 

Zak99b5

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Oh anyone know how long I have to wait for the clear to cure before I tape the rub strip back on the door?
 

Zak99b5

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BobnOH

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May 29, 2004
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central Ohio
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New Beetle 2003 manual
It's beautiful. Good practice for doing the rockers. Possible you'll be getting replacement doors in 2 or 3 years, those sanded spots, even when treated with magic goo, always seem to continue rusting. Hope I'm wrong..........but used doors are cheap..... When (if) you do the rockers, cut them back well beyond any damaged area and weld in a piece of metal.
 

Zak99b5

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2003 Jetta TDI
Thanks. Yes, this is really just practice.

I moved the car, and with no direct light you can see how close the color match is.

I didn't paint the rocker, front door, or the forward edge of the rear wheel well. Also, no new base much above the rub strip. And yes I see the dent in the wheel arch--happened a couple days ago when a kid at the beverage center was loading a keg in the back seat.
 

snakeye

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Dec 13, 2009
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2003 Jetta and Wagon, GLS 5sp
Oh very nice job, and the color matched really well. You're using adhesive for the strip right? I wouldn't rush it. Maybe wait a few days or test that it's fully hardened in a spot behind where the strip goes. Rain is not a problem, there are drain holes on the bottom of the door.
 

tgray

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I would take the panels out and treat the inside where the holes are with something like fluid film. If you don't it will return even worse as the moisture will get under where you painted. Rust like this usually starts from the inside and then pushes out under the paint.
 

Zak99b5

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Albany NY
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2003 Jetta TDI
Fluid film on the back side is a great idea. It should put off the inevitable for a bit longer.

I'm going to wait about a week before I wet sand the clear down, and the run strip will go on after that. It will be much easier without it.
 

Zak99b5

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KrashDH

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Washington
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I just went out to move the Jetta, and I noticed the clear looked quite a bit better than it did right after I sprayed it. It's cured about 20 hours now, and looks like this:

Compared to the factory finish on the front door the reflection still isn't as clear, though.
Looks really good. You wet sand that up to about 3k then hit it with a polishing compound and it'll go mirror on you depending on how deep the orange peel is. But I think after what I mentioned you'll be pleasantly surprised!
 

Zak99b5

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Yes going to wet sand with 1500 >3000>5000 then rubbing compound > polishing compound.

I only have a crappy harbor freight buffer. Should I just use the foam backing on it with the rubbing compound, or a microfiber bonnet?
 

KrashDH

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Washington
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Yes going to wet sand with 1500 >3000>5000 then rubbing compound > polishing compound.

I only have a crappy harbor freight buffer. Should I just use the foam backing on it with the rubbing compound, or a microfiber bonnet?
I've used the harbor freight DA buffer with the foam velcro backed pads with great success...after wet sanding by hand
 

Zak99b5

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I’ve got the $23 10” random orbit 3000 opm polisher. Not quite sure on technique. If I apply pressure, it slows down. It only gets to max speed when it’s almost floating.
 

snakeye

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Yes going to wet sand with 1500 >3000>5000 then rubbing compound > polishing compound.

I only have a crappy harbor freight buffer. Should I just use the foam backing on it with the rubbing compound, or a microfiber bonnet?
Rubbing compound and 5000 grit may be redundant. I'd pick one. You can also wet sand by hand.
 

Zak99b5

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Good to know. I'll go straight to the polishing compound then. Can always use the rubbing after if needed (that's what she.....)
 

KrashDH

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I’ve got the $23 10” random orbit 3000 opm polisher. Not quite sure on technique. If I apply pressure, it slows down. It only gets to max speed when it’s almost floating.
Only use the DA for polishing/compound, not for sanding.
As far as technique goes, let the DA polisher do the work, do not apply a lot of pressure. Really none at all. The more pressure on that thing the more it'll bite and give you the opposite results you want. Just a light hand and let it do the work with the compound after.
 

Zak99b5

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Yes, wet sanding by hand. Didn't even think of using any kind of machine for that.
 

Mass. Wine Guy

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Looks really terrific. I’ve done some similar work on side and rocker panels. Clear can take a while to cure fully. I’d wait a week. Also, short fiberglass strand filler is much better, at least for the first layer. You can put regular stuff on top. I also have the Harbor Freight machine. Fine for this.

Snakeye, how is blending solvent used? Blending is the most difficult thing.
 

snakeye

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Looks really terrific. I’ve done some similar work on side and rocker panels. Clear can take a while to cure fully. I’d wait a week. Also, short fiberglass strand filler is much better, at least for the first layer. You can put regular stuff on top. I also have the Harbor Freight machine. Fine for this.

Snakeye, how is blending solvent used? Blending is the most difficult thing.
I don't really know if it's meant to be used this way, but say I have a small area that needs to be painted. I will sand a much larger area around it with a fine grit, then overspray it , and then spray the blending solvent over that while the paint is still wet. It kinda spreads out and levels the overspray, creating a seamless transition between it and the paint underneath it.
 

Mass. Wine Guy

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Man! That sounds great to me. I’m buying some asap. I can seldom double fold paper the right way to avoid sharp division lines.

You must have to spray lightly to avoid running.
 

Zak99b5

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2003 Jetta TDI
Trick is NOT to fold it. Tape along one side to the car above where you want the "edge" to be. Then loop the bottom edge of the paper to match the taped edge, creating a roll. Tape it in place.
 

Zak99b5

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Ok so waited 6 days for the clear to cure.

Wetsanded using a sponge for a block 1500>2000>3000>5000 then polishing compound with HF rotary.

On to the pics.









I was thinking I sanded basically all the clear off. I had gotten the paint pretty flat and level, but after polishing it just wasn't shining like it should.

Relflection looked pretty damn clear, but there was no depth to the shine, and it looked kinda cloudy or hazy. At an angle it looked good, but head on no real gloss. Tried scratch & swirl remover, which seemed to help a little, but not a lot. Reinstalled the rub strip and washed the door with car wash.

Then I moved the car so the pax side was in the sun. Now I see the problem. Sanding scratches are still visible. Not sure if it's product, equipment, or application error (or any combo thereof).

Pretty discouraged about all this. Any way to save it?
 

Nero Morg

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I'll ask my dad what he thinks when I get back home, he was an auto painter for 35 years.
 
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