adhesive vs welding

[Dreamcar]

I noticed that the factory had applied a seam sealer prior to spot welding the cowl on. Like most cars, the cowl creates an inaccessible cavity that drains the water getting into the vents under the windshield. However, once the cowl goes on, there's no way of getting seam sealer inside the cavity to stop water from getting between the upper and lower cowl panels.

However a test I did showed me that seam sealer designed to survive spot welding does not survive plug welding.

From what I know about autobody adhesives, they are great but not recommended for structural pieces. Would the upper cowls be considered structural? If not, than an adhesive would solve all ky problems.

Anyone have any suggestions?

[Mike DC]

  


You could try using adhesive to do most of the joining work.  Then add a few spot welds (perhaps in high areas) just to hold everything all locked in place.  

[Dreamcar]

I was thinking that too. I should also mention that only the upper cowl is being replaced...the lower cowl/plenum has remained.

[sardillim]

Personally I would not use an adhesive for the upper cowl panel.  I would plug weld the panel and look into a spray on seam sealer and try to make up some sort of a wand to get to the hard to reach area's 


Good Luck !

[Indygenerallee]

It would be fine to use Lord Fusor on a cowl panel.

[bill440rt]

It would be fine to use Lord Fusor on a cowl panel.

x2
Should be fine for this application.

The reason why manufacturer's do not recommend the use of panel adhesives for structural components (frame rails, etc) is because it may alter the way a vehicle reacts in a collision. (This mainly applies to modern cars.)

Vehicles nowadays are designed to crumple. Frame rails have built in crush zones, can be comprised of different metal strengths in the same part, high strength and ultra-high strength steels, etc. Even the number & distance of spot welds can affect the way it reacts in a collision. Different strength steels also are found in inner reinforcements, hinge pillars, etc.
Panel adhesives are supposedly stronger than welding. Before there was a spot welded panel with welds like this: *   *   *   *   *
Now there is a glued panel with a full bead like this: *****************
The adhesive, being stronger, could affect the transfer of collision energy in the vehicle in the event of a crash.

If you use adhesive, just make sure each mating surface is clean bare steel, and be sure those areas are covered with adhesive so there are no exposed metal areas once the part is clamped. Once clamped it'll smoosh out nice on the inside, and you can smooth out/brush the excess on the outside leaving a nice seam sealer look.

[Dreamcar]

Thank you for the replies. I hate this decision...if I weld it, I'll be worrying about corrosion protection....if i use adhesive, I'll be worried about structure

[green69rt]

I had the same problem and thoughts when replaced my upper cowl. I ended up using a wider than normal bead of seam sealer on the edge that the windshield sets on, the other edges are not so important.  I did plug weld and it did burn the sealer.  If I were doing it again, I would just cut notches in the upper cowl flange and weld as close to the edge as I could, keep a wet rag handy to quench the heat so it will not destroy the seam sealer.  After all that work I then got a old garden sprayer with a flexible wand and went up thru the air vents and sprayed water all around to see of I had any leaks.  I found a few so I took some 1/4" inside diameter tygon (sp?) tubing and clamped it on a tube of SEM sealer and was able to get the end of the tube right on the spots.  Tested with the garden sprayer again all was well.   I was surprised how far I could get my arm up into the vents!  I could even get the end of my finger to the seam in some spots.

Look here for what it looked like...

http://www.dodgecharger.com/forum/index.php/topic,54582.100.html

[Dreamcar]

I had the same problem and thoughts when replaced my upper cowl. I ended up using a wider than normal bead of seam sealer on the edge that the windshield sets on, the other edges are not so important.  I did plug weld and it did burn the sealer.  If I were doing it again, I would just cut notches in the upper cowl flange and weld as close to the edge as I could, keep a wet rag handy to quench the heat so it will not destroy the seam sealer.  After all that work I then got a old garden sprayer with a flexible wand and went up thru the air vents and sprayed water all around to see of I had any leaks.  I found a few so I took some 1/4" inside diameter tygon (sp?) tubing and clamped it on a tube of SEM sealer and was able to get the end of the tube right on the spots.  Tested with the garden sprayer again all was well.   I was surprised how far I could get my arm up into the vents!  I could even get the end of my finger to the seam in some spots.

Look here for what it looked like...

http://www.dodgecharger.com/forum/index.php/topic,54582.100.html

Interesting...did you allow the sealer to cure before welding? I did a test with still wet sealer. It appeared to survive the plug welding until I loosely pulled on it after 24hrs and the sealer came right off. My conclusion is that it would not take much for water to get behind it.

[mpd659]

You could weld it and then put the panel bond over the weld. My friend did this on the back of a fender and it has been 12 years with no issues.


Russ

[Dreamcar]

You could weld it and then put the panel bond over the weld. My friend did this on the back of a fender and it has been 12 years with no issues.


Russ

With the cowl panel, once installed, getting to the back of the welds with seam sealer is very difficult.

[hemi-hampton]

I'm not sure the cowl would be considered a structual part. Highly unlikely to take a direct hit in a accident also. I've seen people glue whole roofs on, I'd be more worried about that then a little cowl piece.  LEON.

[Dreamcar]

I think I will not bother with the sealer since I easily burnt it off when plug welding a test panel.

The lower cowel has already been painted with chassis saver, and the upper cowel is coated with epoxy. I'm going to clean the mating surfaces and coat with weld-thru primer. After welding the panel on, I'll spray inside the cavity with eastwood frame coating I have that comes with a conical spray nozzel and two foot tube. This stuff is thin so it creeps well into crevises.Then, I'll seam seel the outside. Once the car gets painted in a year or two, I'll get some type of rustproofing sprayed in the cavity. Since this will be a garage kept fair weather car, I hope his will be enough to keep rust at bay.

[Charger-Bodie]

I would panel bond it. In fact I have on a couple cars now.

[Dreamcar]

I would panel bond it. In fact I have on a couple cars now.

What about torsional stiffness? Do you think the fact the lower cowl is still factory welded it would be ok to bond it?

[Charger-Bodie]

As long as the rest of the pieces are in good condition I would be just fine with bonding it.

[bill440rt]

As long as the rest of the pieces are in good condition I would be just fine with bonding it.