Cowl Vent Repair

[zigmont]

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.

 

[enferno]

i wouldn't do anything less then weld it. the cowl plays a part in some of the structural support for the front of the car there, and i would be worried about it popping off the adhesive. if you weld it and grind it, it will be a lot nicer looking finished product as well.

 

[2+2GT]

The cowl is essentially a torque box that joins the sides of the car together, it's not just cosmetic. I'd weld it.

 

[Red5oh]

Only choice is to weld it... I would also buy the new setup that comes complete, not the repair panels... otherwise you will be taking out about 350 spot welds, and that is a LONG task.... Plus the metal will be new from the aftermarket and all will be good. Just clean up your new outer portion (the original one) and you will be good to go.

 

[jamimac]

Only choice is to weld it... I would also buy the new setup that comes complete, not the repair panels... otherwise you will be taking out about 350 spot welds, and that is a LONG task.... Plus the metal will be new from the aftermarket and all will be good. Just clean up your new outer portion (the original one) and you will be good to go.

Ditto on this. I've done 3 and it's gonna suck, but no use making it worse than it has to be.

 

[zigmont]

Thank you for all of the responses. 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.

 

[enferno]

water isn't the concern with the adhesive, it's the structural integrity of holding it all together. is it worth it to you to use the adhesive, have the car painted, then risk the cowl popping off? even if it doesn't come all the way off, it could crack and break the adhesive and create spots for leaks, not to mention the weakness and risk of having to repaint. as said before, the cowl is a major structural part of the front of the car.

 

[jamimac]

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

I just don't understand, why not do it the right way? You seem to have made up your mind before you asked the question. There's only one to make the repair and not have problems and that is to weld it. You will without a doubt have problems with the adhesive.

 

[65-Fstbk]

Wow, I have to say I agree 100% with the others. The cowl is a very important STRUCTURAL member on the front end of those cars. Case in point, look at how many spot welds Ford originally put it together with. Buy a welder, take a course and weld it or have someone come in and weld it for you.

I would never use adhesive on such an integral part of the vehicle. I can't believe you're even considering it.

Just my 2 bits.

 

[GNGREN]

Thank you for all of the responses. 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 bit if you read the label on the product you are getting it says not for structural repairs. Even all the adhesives used on new cars are only to hold the panels on, never anything structural.
You also need to think about it this way. If you ever decide to sell the car would you disclose how the cowl was fixed? Would you take responsibility if a catastrophic failure happened due to the glue breaking. Do you think someone would give the same dollar amount if they new the cowl was glued and screwed on?

 

[chromedog]

there would be nothing wrong with using a STRUCTURAL adhesive anywhere else, a cowl repair just isnt one of those places...and trust me guys, a properly glued panel wont "pop" off... key is to prepare the pieces to be joined the right way, adhesive on both pieces, clamp firmly, but not so tight as to squeeze all the glue out, and LEAVE IT ALONE until the adhesive cures!!!

 

[zigmont]

Cowl repair

Does anyone remember a while back that a Ford TV advertisement bragged that they could support the entire weight of a Ford truck with just one of the bolts that held the bed on the chassis? (they hung the entire truck up by one bolt)
I do.
Therefore, I am amazed that no one has given any consideration to the fact that there will be around 110 sheet metal screws holding the cowl along with the adhesive. Even if each screw had a gripping force of only 20 pounds, you would have a combined gripping force of over a ton (how much is enough??)holding that flimsy 20 guage sheet metal cowl on the car, and that doesn't take into consideration the holding force of the adhesive. I never said that I would grind off the screws, only the portion of the threads that stuck through the cowl.
I have been welding off and on for around 49 years (yes I am old)
I replaced the cowl vents with patch panels a few years back on the 65 Fastback that I am currently driving. I ground special drill bits that would drill a flat bottom on the hole so I could control how many layers of metal I drilled through. I made sure that every spot weld I drilled out still had the bottom layer of metal intact so I would have something to weld to when I replaced the cowl. I welded the cowl back on again. What a pain in the butt that was. 110 welds, and I'm not doing that again.... Ever!

I guess the whole issue here is just how strong does it have to be to get the job done....
I can tell you this.... In the type of work I do I install a lot of electrical conduit. I attached an electrical junction box called "4 square" to a column with 1 (one) #8 sheet metal screw, today, and it would support my entire weight of over 250 pounds without popping the head off. Multiply that times 110 and see what you get.

I stand by my decision to glue and screw.

One last note: I think everyone must know that the reason Ford used spot welds to assemble their cars was because it was the CHEAPEST WAY, not the only way.

 

[Bullitt347]

+1

 

[GNGREN]

I can tell you this.... In the type of work I do I install a lot of electrical conduit. I attached an electrical junction box called "4 square" to a column with 1 (one) #8 sheet metal screw, today, and it would support my entire weight of over 250 pounds without popping the head off. Multiply that times 110 and see what you get.

I stand by my decision to glue and screw.

One last note: I think everyone must know that the reason Ford used spot welds to assemble their cars was because it was the CHEAPEST WAY, not the only way.

LOL the old electrician mentality gota love it (Master in 3 states here).... How about ya hang on that box and have a helper smack it with a hammer and see if that little screw head and you fall to the ground. I even tried to find the stuff you mentioned and all I saw was structural plastic adhesive. I looked in the past for a structural adhesive and even if that is what they are called all of the disclaimers on the products say not for a "STRUCTURAL" repair. You really need to read the fine print. Think about all the stress and vibration that a cowl takes. The shock it gets hit with hitting bumps in the road that the suspension doesn't absorb.

Car manufacturers today use the adhesives but not on a structural part, only panels.

 

[NasaGT]

I've used structural adhesive several times and the stuff is pretty stout. I wouldn't use it for a cowl repair though. If you've ever re-skinned a hood or rear deck lid, you've had to get the structural adhesive to let go between the skin and the bracing. The easiest way to do that is to apply a little heat to it. A couple seconds with a torch to warm the metal and the adhesive will let go. Given how hot an engine compartment can get, I'd be worried about the adhesive letting go. It certainly won't happen instantaneously, but every heat cycle may eat away at the bond.

Just my 2 cents.

 

[zigmont]

OK Let's play devil's advocate.
What exactly would happen if the adhesive and the screws somehow failed to secure the cowl?
Would the rest of the car slowly (or quickly) fall apart?
Would the car become dangerous to drive?
Would the cowl fly off and maybe kill someone?
Anyone with any common sense can guess the answers to the above questions. (no, no, and no)
So what if it comes loose?
Then I will weld it.
But I would still have had the satisfaction of trying something new and different that others were afraid to try.
But if it works out the way I believe it will, I can always say that I was the first one to do it.
Also, repairing cowl vents this way could move cowl vent repair out of the $1200.00 to $2000.00+ range to something much more affordable and doable by the average person with some mechanical skils.
After all, isn't doing things differently the way the automotive industry has evolved over the years?

 

[2+2GT]

OK Let's play devil's advocate.
What exactly would happen if the adhesive and the screws somehow failed to secure the cowl?
Would the rest of the car slowly (or quickly) fall apart?
Would the car become dangerous to drive?
Would the cowl fly off and maybe kill someone?
Anyone with any common sense can guess the answers to the above questions. (no, no, and no)
So what if it comes loose?
Then I will weld it.

As for #2, with a failed seam on the cowl, the car will loose torsional stability, so yes. The cowl isn't just cosmetic, it's as structurally important as a frame rail.

BTW, with the screws ground down, their holding power approaches zero.

I can't see where your saving a significant amount of work with the glue vs. rose welds, so the financial benefit is negligible.

 

[2+2GT]

Car manufacturers today use the adhesives but not on a structural part, only panels.

I had it straight from a Ford engineer that the skin of the quarter panels was intended to bear 20% of the structural load.

 

[jamimac]

But I would still have had the satisfaction of trying something new and different that others were afraid to try.
But if it works out the way I believe it will, I can always say that I was the first one to do it.

lol, you won't be the first hack that tried this and nor the last. Like someone else said, Just make sure that if you ever sell it, tell them how you fixed it.

also I heard silly putty was better to use than adheasive.

 

[zigmont]

Cowl repair

I don't appreciate being referred to as a "hack" I have been sucessfully repairing automobiles for over 45 years little boy. How old did you say you were????