Welding question

[Cbridgewater]

So, I am choosing to completely weld the seams where the Rear Deck filler meets the quarter panel. My question is, do I need to fill the low spots with another weld, or filler? What would you all suggest?

[JS29]

Seam sealer! 

[Mopar5]

When you say rear deck panel you mean the panel that extends to both quarters that the rear glass sits if that is the case I wouldn't keep filling that with weld the more heat you put on it the worse distortion is going to be. I would fill the rest with short strand fiberglass.

[Mopar5]

Just another thought if you keep grinding into the adjacent metal you make it super thin and worhtless

[IRON MAN]

Do not use fiberglass. Eventually it will delaminate and rust will appear.

[jimynick]

Short strand fibreglass is stable as hell and I've never seen it come off/deteriorate in the 30+ years I've been using it. Regular cloth or mat fibreglass? Well, that's a different story. The first stuff we saw in the 70's and 80"s was called Tiger Hair. It was and is waterproof and much stiffer than regular old bondo. And, it's in those grooves on my car, so I guess we're both taking our chances, eh? 

[Mr Lee]

Can't he just continue to weld it closed as long as he welds it slowly / a little bit at a time, to keep it cool?  Then file it flat? 


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[MoparLeo]

Welded properly, there would not be the low spot(s) like in your picture. The panels should have been butted together and the weld would have filled and built up above the seam. There would be no low spot after grinding.

[hanksemenec]

I'll be doing the same job soon. How big was the gap when you started?

[Mopar5]

Its just not necessary to completely fill that seam with weld

[Cbridgewater]

With the rolled edges at the quarter and deck filler, there is quite the gap to fill with a quick weld (to avoid too much heat) to fill. I can definitely make additional passes to build it up, but don't want to risk any distortion.

[Cbridgewater]

Once the panels were clamped and welded together (before filling the seam with weld) I held a straight edge across the top and would say that the gap was about 1/4", reducing down to nothing. If you looked at a profile of the gap it would be like the drawing below.

[hanksemenec]

If I'm doing the same the same fill job, I'm thinking of silicon bronze filler on top of weld. How compatible is the silicon bronze with paint and body material?

[IRON MAN]

Short strand fibreglass is stable as hell and I've never seen it come off/deteriorate in the 30+ years I've been using it. Regular cloth or mat fibreglass? Well, that's a different story. The first stuff we saw in the 70's and 80"s was called Tiger Hair. It was and is waterproof and much stiffer than regular old bondo. And, it's in those grooves on my car, so I guess we're both taking our chances, eh? 

Fiberglass resin does not expand and contract at the same rate as sheet metal and will eventually delaminate. At this stage of the OP's repair I recommend using a two part epoxy preferably JB Weld. JB Weld works great as a body filler and has the tendency to self level making it easier to finish the work. JB Weld expands and contracts at a similar rate as the sheet metal. I have used it with great success.

[JS29]

I would be more concerned about body flexing! that is why i suggested seam sealer.