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Is there a weld-through adhesive?

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TR4nut

TR4nut

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Quick question as I plan on replacing a floorpan- I've heard about panel adhesives, but are there any out there that can be combined with spot/plug welds?

Thinking of going the easy route and cutting out most of the existing floorpan in my 3A, leaving maybe 1/2 to 1" of flange area - thought it might be feasible to apply a bead of adhesive along with the planned plug welds - is that possible?

Thanks,
Randy
 
I don't personally have an answer to your question, I have used both welds and adhesives, but not at the same time on the same panel. I am curious though, why do you think you need to use both? One or the other would do.
I have only used adhesive on body panels, never a floor pan, they work great, but I normally use welding anyway .....just case I like to weld when I get the chance.
 
I was thinking it would serve as an effective seam sealer at the same time and provide even more strength/rigidity to the plug welds around the perimeter. Given lack of response though, I bet its not a good idea!

Randy
 
Used panel adhesive to install floor pans in the MGB here. Pop rivets every few inches instead of welds. The things are well-and-truly IN there. Same technique for "dogleg" patches.

Before doing the deed we bonded some scrap pieces and tortured 'em to get some empirical info... It was amazing what it takes to break that bond. We're convinced. The SEM product is what we used.
 
I won't say that it cannot be done... but it seems to me that the two techniques are incompatible... I'd suppose that the adhesive would compromise the integrity of the weld, thinking that clean metal to clean metal makes the best weld; and that the extreme heat involved in welding would compromise the chemical bonds.

I've no experience or empirical data, but that's how it seems to me....

Others may have more informed opinions, or real experience... maybe?
 
James-

I haven't seen anything definitive on the do's and dont's of application - but I agree completely with your logical discussion. Just thought maybe there was a magical elixer out there that would act both as a viable weld-through primer and help strengthen the final construction. Probably would need an extensive respirator setup anyway if it did exist, given the combination of welding heat and exotic chemistry in the adhesives.

Randy
 
I can't imagine a spot weld working at all. The adhesive would create an electrical barrier which could keep the metal from reaching the proper temperature for fusion.
 
Yup. :iagree:

I've got some vestigial recollection of a "weld through" coating of some type but can't find info on it now... Mebbe Kerry will see this and chime in.
 
That's pro'lly what I'm recallin', Greg.
 
When the last-gen Camaro/Firebird was still being built (in Ontario) they wanted to find a way to improve the chassis without making a big engineering change (the car was close to the end of its run at that point).

They added some sort of adhesive to the panels that were also spot-welded. This stiffened the chassis a great deal and was considered a real success. My guess is that the adhesive was between the spot-welds but I don't know all the details.

There's probably some Camaro/F-body forums out there with more info on this.
 
I don't have time to research it right now, but if someone has the time and inclination, see what you can find out about the Panoz construction process.

I know the Esperante with uses aluminum frame is glued together....
 
Randy
You got me thinking (a dangerous process). How about using sheet metal screws to line up the patch. Then remove. Punch out your plugs, then glue only away from the screw/punch holes and then use a washer on your sheet metal screw to tighten the joint. Remove the screws and weld.

Anyone have 3m or fursor gun they will lend me?

Paul
 
Paul-

I'd lend you a gun if I had one - I'd like someone else to test it out before I mess up my floorpans!

Randy
 
I just disassembled my '77 Corvette - that bonding material holding the fiberglas panels together is harder than welds!

Oh, I use FUSOR to glue floors into MGB's.....& you don't need any spot welds if you use it.....they would actually be weak points.
 
I actually replied to this post earlier but ..... must have missed submitting somehow so .... here goes again
The auto body industry actually does use a chemical bonding adhesive combined with S.T.R.S.W. {SQUEEZE-TYPE RESISTANCE SPOT WELDING}
NOTE: not plug type spot welding like we have to do with our M.I.G.`s
I don`t think we could accomplish the clamping force necessary to produce a good reliable weld along with an adhesive bond with our restricted weld methods.
Chemical adhesive bonding in the auto body industry has come a very long way. I would not hesitate to use this method alone and forgo the welds.
In fact adhesives are much more efficient at keeping moisture at bay, especially in critical areas like under body repairs than spot welds could possibly be. I would also like to add that additional fasteners as some have suggested would not be my choice for the simple fact that I myself would not want to compromise the repaired seam to any possibility of moisture entering the laminated metal and causing the seam to possibly rust out again.
Just my opinion:
If you leave the one inch lip as you suggested and ensure that you apply enough bonding agent that it squeezes out both sides of the seam to ensure you encapsulate the laminated areas with adhesive i`m reasonably sure you will not have to worry about separation or rust through of these seams in your lifetime.
There is my 2 cents.
 
:lol:

And here I thought you were just ~avoiding~ an answer, Kerry! :wink:

I agree with ya about "extra" fasteners possibly introducing unnecessary weakness in time but the reason I used 'em was that the replacement pans wanted to "crawl" a bit, out of position. Decided the "risk/reward" factor was acceptable in the circumstance. Well isolated/insulated the pop-rivets on inside and out with paint and coating.
 
No Doc I wasn`t evading :p. Actually I was on another camping excursion for the first three days of the initial appearance of this thread. As I mentioned I did ATTEMPT one reply but messed up the submission somehow *SMILE*. Thinking about what you said about fasteners, I assumed {a bad habit of mine}{assumptions} one would cut, nip, and tweak the replacement panels until they fit in their perspective positions without the use of screws and/or rivits. In addition, in order to hold the panels in place, possibly some heavy weights strategically placed would suffice to prevent "creeping and/or crawling.
In any case screws and/or rivets would be a last resort for me. But bare in mind I would resort to using them given no other options.
P.S. I also had an article I wanted to post about adhesives and S.T.R.S.W. methods used in the auto body industry that may be pertinent to this thread but somehow managed to lose it too! go figure.
In any case we, that is most of us do not have the proper equipment {welder} to accomplish S.T.R.S.W. welding adequately anyway let alone access to the proper adhesive for this type of procedure either.
I myself would go with the adhesive bond and I would only use screws and/or rivets ....... if absolutely necessary.
 
Kerry-

If you are endorsing adhesives I definitely need to rethink my floorpan plan. My MIG handling skills are very limited at this point when it comes to sheet metal welding - so I'm going very slowly to avoid making a mess of it. The perimeter of my drivers side pan is in very good condition, the only repair area really needed was below the drivers feet. I think I can definitely dress up a flange area in the existing floor, which would allow an adhesive joint. The one different area on the TR3 is the rear joint- the floorpan laps below the rear section of the cockpit, so perhaps clecos or pop rivets would be needed there.

Randy
 
Randy:
All I`m basically saying is the modern way of bonding body panels compared to the old school methods are far superior to spot welding alone.
In the fact that adhesives create a far superior moisture barrier than spot welds can and the bonded area are adequate in strength
Assuming again, as I have not done floor pans on a TR that one could avoid using mechanical fasteners. But as you state in some areas fasteners may not be avoidable which in that case either welds or mechanical fasteners would be the obvious choice. In those areas the only thing I would do is ensure that a sufficient moisture barrier is incorporated into the seam.
Not matter what the repair methods used our object is to ensure that our cars last as long as humanly possible without rusting away.
Although my previous occupation was welding i`m not so stuck on welding that I would insist that you use weld methods only, when there are better solutions.
 
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