Plug Weld ? Need advice

rustover

rustover

Member
This may be a stupid question, but I thought I would get some advice before I proceed. I'm replacing the deck filler panel on my 72 Camaro, and I have the panel test fitted and in the same location as the original. At first glance I notice they short changed me some metal on the flange that welds to the trunk gutters for the weather stripping . Here are a few pics of what I'm talking about.





To me it looks worse in person than in the pics. I was planning on plug welding this area with 1/4 inch holes. I don't have enough metal for 1/4 inch, I could maybe do a 3/16. I was also thinking about just doing some stitch welding in this area. I guess I could get creative and butt weld some metal and then do the 1/4 inch holes.

Anyway just wanted to ask what would be the best method.

Thanks for the help,

Russ
 
You are going to grind the welds down and seam seal the gutter anyways so I'd plug weld where the flange is right and just put some edge welds where they shorted material. Once seam sealed and weatherstrip installed it will make no difference.
 
we have gotten a bunch of bad reproduction parts, Camaro fenders we needed to cut the bracing at the body line bend so it would match the door.

If you can get a grinding wheel to fit in the gutter, you can do alot of edge welding. you might condider getting a punch instead of drilling that panel and actually punch half moon holes where it is short, the plug is gonna melt the metal around it anyway and at least you would still have a plug weld, even thought it is an edge plug weld. You might be able to make a jig and drill those holes half moon so you can pound it flat again before putting it back in the gutter if you cant get a punch.

the replacement is really not right or wrong, its probably too close and the manufacturers expect that edge to get trimmed.
 
One thing I can tell you for sure, you better put it all together with screws or rivets before "weld one," because those rear deck panels are notorious for having a different contour than the deck lid.

If your welding skills are good and you have proper protective equipment, you could weld that panel from the bottom so you have much less grinding to do within the channel.
 
Thanks for the replies guys. A grinding wheel does fit in the gutter area. I would like to weld it from underneath but I'm still working on my skills. I have repaired some holes from removing the old panel and welding some from underneath. That's a total different ball game. It's harder to see and not as comfortable. Crash that's my next big hurdle, getting the deck lid back on.
 
I agree with Crashtech. I would screw that thing down and test fit the trunk lid to make sure you have proper fit.
 
Last one I did, ('70 GTO)I had to mock up the lid, back glass, and reveal moldings, and it was a good thing I did because quite a bit of reshaping was needed.
 
Thanks for the replies guys. I hope to finish mocking it up soon. There is not a lot of movement in this panel and it looks to be a decent stamping. The hinges are going to big the challenge. I'll keep you guys posted.
 
One other question I have is about separating panels. I have noticed that the metal was weak in certain areas where there was an original spot weld. I believe this is because the original spot weld was indented from underneath and when I separated the panel in some of these areas there was not much metal left. I plan on picking different locations to do my plug welds when I re-install. I didn't really notice this when I separated the trunk floor, I know the frame rails are thicker, but the factory spot welds on the inner fender locations (still though indented) are not weak. It could be that gm really had the power turned up when they welded this panel in. I really notice this on the trunk gutters. I had several holes after I ground off the top metal. I could just push a knife through the original spot weld locations.

Has anybody else ran into this. Can it be prevented or is it just the nature of separating original spot welded panels. Thanks, Russ
 
Flat face on the tips and rounded profile in the channel may have pulled the "indent" in farther......
 
Back then the factory used large manually operated spot welders suspended by a weight balancing cable that went up to a wheel on a wire that allowed the spot welder to float around so the operator could keep up with the assembly line. They worked quickly to keep up with the line and get their designated spots done, then move the suspended welder to the next car. It took awhile to get use to controlling the inertia the moving welder put on the cable attached to the wheel on the overhead wire, depending on how fast the operator moved the spot welder. Accuracy, and quality to some degree were traded for speed. These spot welders were big enough to get the metal red hot, just look at the sparks, and thats why some of the spot welds on our cars are in all shapes and contours. If they pushed down on the welder, the metal was so hot that the spot could sink.

The new bodys that are being assembled today by Real Deal Steel are also done with similar spot welders, but much more controlled and using two operators.

spotwelder_zpse3b9ca30.jpg


spotwelderheat_zps949a1e3e.jpg
 
Do you guys think I would get a good plug weld at the rear channel with a 3/16 hole. There is just not a lot of flange area. I've mocked the panel up with screws and marked my plug weld areas. All the measurements are looking good. One thing about this panel is there really isn't a lot of adjustment. I still need to verify the hinges. I'm also thinking about replacing the trunk gutters that attach to the 1/4's. I'm still trying to decide. Mine were really spot welded like crazy in a short distance and I ended up with several thin spots on them. I have repaired them, just not sure if I'm happy with them.
 
do a test panel with a 3/16 hole and check for weld quality, you might have to turn the heat up a smidge but I bet you'll be fine

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Another option is to glue that area-easy!
 
Thanks Bob. I will do some testing. I also thought about the glue. I might go that route, but I would have to purchase the gun/glue. I need to get the gun anyway. One more question. I may have over did it on my plug welds holes along the top. What is a good rule of thumb on spacing? One things for sure, these panels are under a tremendous amount of stress due to the torsion rods that lock under the hinges.
 
I think a 3/16 hole for plug welding is very risky, its just so hard to keep from welding just on the edge of the hole instead of on the bottom panel, and you may never know if you have a good weld even though it will look good. 5/16 is recommended for plug welds. As long as you have 1/2 inch contact, panel bond will be very easy, at least as good, no finish grinding, and excellent rust proofing.
 
There's a few companies that offer panel bonding adhesive that work in a regular caulking gun, I haven't tried them but I think SEM is one. Fusor is what I normally use.
 
I use a letter A bit for all my plug welds, which is a .234 diameter. I do run the welder hot so it does a good weld. I have also seen the 5/16 recommendation but feel that may have been put out by I-Car for all the guys that don't know how to turn up the heat, it still gives them a chance for a weld that holds. I don't recall seeing any factory spot welds that large in diameter where they are used on 19 gauge sheet metal, so didn't feel it was warranted for plug welds either. I think if you can be fairly accurate at hitting the center of the hole so the arc starts on the back part and let it fill in the hole, add a bit more heat to insure a good weld, then you will be fine with the 3/16 diameter. As with anything, do it first on a couple practice pieces, do one plug weld and see how it holds to a twist test. If it doesn't hold, add more heat. If it does, rock on..
 
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