Rear quarter welding-caused warp

[jclayc]

I have a 63 beetle where I welded in a new lower part of the driver’s b pillar. That went ok but it appears that, when I did it, it ended up warping the flat part of the lower rear quarter panel.

I’ve read that the solution is to hammer out the weld so it un-shrinks the metal and stops the puckering but I can’t really get a dolly behind where the pillar meets the quarter panel to do so. I’ve tried working the low spots just like normal low spots but that seems to just chase the high/low spots around.

I guess cutting the inner part of the quarter panel where the door card snaps in (and welding it back in afterward) might give me some room… or should I just stop obsessing over it and skim some filler in there?

[67ctbug]

Stop obsessing and skim it
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[esde]

If the high spots are too high, get a shrinking disc and learn how to use it.
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modok wrote:
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[jclayc]

I thought about the shrinking disc but the issue was caused purely by welding…. Which shrank the metal. You don’t get rid of shrinking by more shrinking right? (Even though I agree my first thought was to shrink that high spot in the middle of the dips)

[VW_Jimbo]

Curved block of wood and a pry bar from the inside. Take the window out. Reach through the window with one hand and push on the prybar. With the other hand, take a hammer and strike the panel as needed. The high spots!

Once close, filler to finish.
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[viiking]

I had this exact problem but on the front quarter panel near the fuel filler door. Didn't matter how careful I was welding and cooling in between you still get the dreaded valley where you weld.

I purchased a heavy panel beating spoon that would slip in behind the cavity and give me the ability to pry the panel out and also act as a dolly. The heavier the better.

I bought one locally in Australia but there are plenty of curved spoon dollies available in the US. This one suited the narrow cavity between the outer and inner skins.

https://metalmantools.com.au/product/double-blade-spoon-410mm-long/

Here's one from Eastwood that might do the job. There are plenty of other ones around I'm sure. Of course you can improvise as VW_Jimbo says ands use a pry bar and wood.

https://www.eastwood.com/double-end-s-spoon-nv.html
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[metalchomper]

Here is the link to my thread on one of the replacements I did. I welded it with a torch. I did cut an access in the inner structure so I could work the welds with a hammer and dolly. Had to use my homemade shrinking disc when I got a little overzealous with the hammer and dolly. When finished, I just used my mig to weld the inner access panel back in.


https://www.thesamba.com/vw/forum/viewtopic.php?t=324503&highlight=
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[Braukuche]

You shrink by heating the metal and then rapidly cooling it, I use compressed air others use a wet rag.
I use a stud puller to shrink as it’s more pin point than a disc. Just heat a spot cherry red then blast with compressed air. Works great.
Unless you have hours to expend AND have the skills to beat a 60 year old beat up panel perfectly flat, you will have to fill. I’d say 99.9999 percent of restorations use filler.
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[viiking]

[Bulli Klinik]

I believe that is what he is saying.

To elaborate a bit on what is actually happening during the shrinking process:

It isn't the heating, then rapidly applying cold that is causing the shrink. In fact, applying a wet rag to what was once red hot metal is hardening the area you want to shrink. A rag can be applied, but it is standard practice to allow the spot to cool to where you can just about put your hand on it.

Here is what is actually happening while shrinking: Using a torch, a small area is heated to a point where is becomes near molten. It doesn't necessarily have to be red hot. Heat causes metal to expand and you can see the area rising up like a bubble, proud of the surface. The area surrounding the heated spot is not expanding at the same rate, thereby trapping the molten metal. When the area surrounding area or the heated area is tapped down, the molecules push into one another as they have nowhere to go, which makes the heated portion of the panel thicker. This provides a "shrink". It can make the panel ugly, but that can be planished out.

This is the same thing that is happening when a panel is welded in. The panel fits perfect, perfect gaps, then once welded, the panel tightens up on the weld. If the fit was good prior to welding, only working the weld and heat affected zone should get you back to where the panel is straight again.

Its a fundamental technique to understand if your doing this kind of work.
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Bulli Klinik
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[Braukuche]