cowl to firewall, bond or weld?

[pywell]

This is great information. I too always thought it had to be welded. I am going to try and reuse my original cowl and straighten it if possible. I am definitely going to replace inner fenderwalls so is this a good candidate for bonding materials or are those pieces considered structural? How about radiator support?

The inner fender I would weld. Its spot welded into place, you could probably get away with bonding but no matter what product you use (for the bonding rather then welding) the glue seperates under heat. I really doubt they headers will get hot enough but my recommendation is to weld. As for the cowl, I plan to bond the sides and front but I am welding the upper area where the dash mounts up. You can do that aswell. For quarter panels you can weld where the factory welds are and use glue in the inner wheel well area. However you CANNOT weld where you glued (its that heat thing again). A proper bonding glue has glass beads inside the material, Thats why can apply emensce amount of pressure with clamps or screws. I would keep the glue to roof skins, quarter skins (not the complet ones, the complete ones need welding). You also can get away with patch repairs with bonding. But anything that attaches to the frame I would weld. Which includes the rad supports.

[elitecustombody]

I just wanted to make sure EVERYONE using these products knows 3 things about bonding panels. 1. YOU CANNOT BOND STRUCTURAL its against the law (depending where you live of course) and its UNSAFE. 2. You must clamp the panels down with even pressure where you are bonding accross the entire piece if you cannot get a clamp down use a selftapping screw or it does not bond properly. And 3 you must prep the bonding surface on both sides where the bonding material is going or you might be able to pull it right off, by prepping the surface (36grit grinding pad or equivelent) to ruffen up both sides. Also clean off any excess completely that was squished out of the panels, paint and bodyfiller will fail if applied over top.

Please read the manufactures directions, which I am sure most of us do. I just dont want to see someones project fail or worse, someone get hurt.

 

been to too many ASE,I-CAR classes? Don't mix late model cars with high-strength steel and 35+ year old cars . Using filler over most panel bonding adhesives is OK, not that I would do it,but anyone with common sense would read tech sheet on a product they never used 

[pywell]

been to too many ASE,I-CAR classes?

Actually up here its a 4 year apprenticeship, its important to know what you are dealing with expecially if you repair cars for a living... Do you want your car to be restored right? Or do you want a hack job... I know Im going to the ICAR guy. I maybe taking this a bit over, but I repair cars to the highest quality so I find it important to do it right and know what I am doing, I get quite upset when I see something hacked together. Thats why I like to share everything I can, not everyone can or has the time to goto proper training and cant afford an expensive bodyshop to do it.

Now lets get back on topic

[alphabuck]

its my understanding the reason you cant use stuff like fusor in some areas of the car isnt because of any weakness in fact its quite the opposite.

structural panel adhesives render oem " crumple zones " ineffective.  im assuming thats because the entire stretch of said area is bonded versus being attached every 4 inches or whatever.

the reason its " illegal " is because its too strong. 

[pywell]

structural panel adhesives render oem " crumple zones " ineffective. the reason its " illegal " is because its too strong.

[jimynick]

Whew! Pywell is right in my opinion and I know, I know. I'm also a licenced guy and while it certainly has it's place, bonding isn't for everything. He correctly mentioned that it doesn't like heat and it doesn't really like impact either so using it in areas where it was exposed to those things is taking a chance. Most of the time bonding is done in conjunction with selected spot welding as Pywell also said and as such, I think you can have your cake and eat it too. Put in some welds where accessible and bond where it isn't. At least that's the way I'm going to do mine. While ICAR can be excessive some times, they spend a lot of time with the manufacturers and product people so please don't just dismiss them. Be safe and do it right the first time. Good luck!

[pscott]

Although I'm not familiar with the bonding products that you all are talking about since I've never used them I would like to mention that there is very little (probably none) sheet metal including brackets, braces, etc... that are not structural since this is the nature of uni-body construction. Unless I had actual numbers for tensile and sheer strength for comparison I would not use bonding solely for anything outside of minor repair. One way I would look at it is that if I felt comfortable riding around with the piece or portion of the piece I was going to bond missing from the car then I would go ahead and bond it. I do like the idea presented by one of our good members where we might consider a combo of the two for sealing and protection purposes. I hope mine and the other members comments have shed some light.