Cowl Vent Repair

I bought a 65 Mustang fastback rolling chassis a few years ago with the idea of building a restomod.
I just bought a 66 Mustang Coupe with a rusted out roof, trunk, and floors to use as a donor car for some of the parts (fenders, front and rear vavence, headlight buckets, bumper brackets, wire harness, windshield wipers, etc) I will need.
The cowl vents are rusted through on the 65, while the cowl vents on the 66 are in very good condition.
I plan to drill out all of the spot welds and take the entire outer and inner cowl off of both cars and transfer the 66 cowl to the 65. While I have the 66 cowl off I plan to sandblast everything and paint it with POR 15 paint.
My question is this:
I am seriously thinking of using a bonding adhesive to re-attach the 66 cowl to the 65 instead of welding it.
There is a company called Lord Fusor that makes sdhesives (eBay item # 10387549095) that are made for bonding body panels.

Has anyone on the forum ever used anything like this?

I am looking for opinions both pro and con about this.
Thanks in advance for your opinions.  

I've not used them personally, but I know panel bonding adhesive is being used more and more in the OEM as well as crash part repair industries. This is similar to what is used to bond the glass roofs into the Mustang, and I know it is used on the Corvette extensively on the assembly line. Would I use the product? Sure. Would I use it for the cowl on a unibody Mustang? Well, not so sure. If you haven't the welding skill maybe someone can come over and weld it all in? I know this stuff is billed as "structural adhesive" but I don't know how comfortable I am with it in this situation.

Maybe check with a few local body shops to see what their experiences have been with it?

HTH...
Mark  
Mark Houlahan
Editor
Modified Mustangs & Fords Magazine

1965 FFR Roadster 427W/TKO-600
1966 Mustang 289-4V/C4
1968 Mustang 4.6L Three-Valve/5R55S auto
1990 Mustang 347/AOD
1998 Escort 2.0L SOHC/F4E-111 Auto
2002 Explorer Sport Trac 4.0L V-6/5R55 Auto

Thank you for the response. The response from other forums has generally been negative about the adhesive, but I have decided to go with it anyway.
I didn't mention it in my original post as I was interested only in opinions about the adhesive, but I plan to drill a small hole between each of the spot welds (about 110) and screw in #8 pan head stainless steel sheet metal screws after I apply the adhesive to secure everything till the adhesive cures. After the adhesive cures I will grind the protruding screw threads flush with the underside of the cowl lip above the firewall where the screws would show, and anywhere else where they may cause a problem. Since Ford puts a sealer on the top lip I will do the same to conceal the screw heads.
There will be no way that water can wick it's way between the layers of the cowl lip and begin to rust as it could if they were welded.
Right or wrong, I believe that glueing and screwing will achieve it's desired purpose for me.  

I am very skeptical. Although I am not familiar with the adhesive I am a mechanical engineer and worked for Ford. The cowl in a mustang is a structural member. The bond needs to resist shear and tensile loads and may be subject to bending moment along its (previously welded) surface. The weld is as strong as the base metal and has roughly the same modulus of elasticity. When you replace this with an adhesive in a joint meant to be welded your placing that material in a joint it wasnt meant to be in. A different joint design might be feasible(say a double lap or foldover design) but the lap type joint you will have to use here is not a good adhesive joint for a structural application. You might have high peel strength but the movement and stretch and heat and cooling of the metal here will break the bond in a short time. These materials are used in low stress applications with joints specifically designed to take advantage of the property of those materials. You see it used for patch panels where structural loads are low but I personally would not use it in what is an integral part of your unibody.  

Wow! That is the best explaination I have had concerning the adhesive.
If I could find a way to reweld the panel using the adhesive as a sealer, and not burn it away I would gladly do it. I am concerned that water splashing into the cowl through the grille on top could wick it's way between the cowl layers and cause them to rust. Especially around the welds.
I actually am planning to weld the upper half of the cowl as I don't see water encroachment as an issue.
What do you think about using 1/4-28 grade 8 bolts with locking nuts for the bottom half. These bolts should have a tensile strength of over 6,000 pounds, so 50 or so of them torqued to their yield tension of around 5200 pounds would provide a combined clamping force of over 250,000 pounds.
I don't really know how to compare a spot weld with one of these torqued bolts, other then the metal would have to tear away from the bolt head to fail, similar to tearing away from the spot weld to fail. What do you think?  

I was thinking what he said - the cowl is structural and glue is not a good idea, but I'm not an engineer.  Weld it or get someone to weld it.  You can put seam sealer on the lip when it's done.  The metal rusted in the first place because of inadequate -or none- metal treatment.  Fix that and water intrusion won't be such an issue.  Bolts will allow the pieces to move against each other and if you are worried about leaks, then 40 or 50 bolt holes are 40 or 50 potential sealing issues.

Plus 50 bolts will look - well, like crap IMHO.  
1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

Yeah I think I agree with falcon on the bolt issue, although I would surmise that you probably have the same strength. When you weld, you paint it first with weld thru primer on the sealing lip and then paint the whole cowl with something like POR 15, leaving just the strip of weld thru primer on the sealing edges to be welded. Its not likely to rust after that. Besides the upper sealing area needs to be smooth and the sides lend themselves to mig welding. The bottom is already bolted at the center and thru the flange I would think extra bolts there would cause an issue of movement and possible leakage and I dont think the flange is wide enough along its full width. Better to mig weld it. A mig rents pretty cheap and your settings are gonna be pretty low so its a small machine that you can learn to do in about half a day.