Minimizing/eliminating witness lines using adhesive for patch panels?

[ol'volvo]

I want to use panel adhesive to replace trouble spots. I figure the time I spend learning to weld to the quality level required for auto sheet metal is best spent elsewhere.

Luckily there is a replacement partial door skin available that ends at a trim line so I'm pretty safe there.

But the other spots are at the top edge of a rear wheel well and an area just below and to the side of a tail light. Areas that I don't want seams showing up later.

One other option I considered is finding someone locally just to do the actual welding if I do the prep/panel cutting etc. Seems if everything is ready it could be a quick moonlight for someone that knows what they are doing.

The lack of introducing heat and the corrosion resistance of adhesives as well as the possibility of still being able to do it in my garage appeal to me but I am worried about seeing my patches reappear in the heat of the Kansas sun.

Any tips to keep adhesive lines from showing?

[pane2k]

Alot of guys are using the 3m/duramix adhesives to do what your trying to do. Its supposed to be very strong and hold up well. However im a bit confused on the whole thing too. When I spoke with 3m last they told me..its great to use in the jams and all the spots you dont see all the time.. But where the quarter meets the sail panel..you should always weld for appearance.. i.e. a line coming through like your describing.

I dont know if the adhesives would hold down good enough. Maybe someone who has actually done it..and seen the longevity of it will chime in.

[ol'volvo]

Judging by the lack of response maybe it just isn't suitable for patches. Eastwood sells a kit they market as being for patches but that hardly means its a good idea. Was hoping some of the experienced members might give an idea if its workable.

Well if I have to weld I suppose I'll do it, it'll just take longer to practice on coupons. I have access to the MIG's at work and want to learn to weld but automotive sheetmetal panel welding seems kind of high up on the skill level to be starting with.

Plus one of the patches is near the fuel tank and I was hoping to not have to pull it.

I'm comfortable with the panel adhesives, a shop I worked at built an airplane out of carbon fiber and used adhesive to piece it together. Very common in aviation so the strength is there.

It'll take a while for the panels to arrive from the Netherlands and work is pretty busy right now so it could be a few weeks before I'll even have time to deal with it.

[Henry]

Judging by the lack of response maybe it just isn't suitable for patches. Eastwood sells a kit they market as being for patches but that hardly means its a good idea. Was hoping some of the experienced members might give an idea if its workable.

Well if I have to weld I suppose I'll do it, it'll just take longer to practice on coupons. I have access to the MIG's at work and want to learn to weld but automotive sheetmetal panel welding seems kind of high up on the skill level to be starting with.

Plus one of the patches is near the fuel tank and I was hoping to not have to pull it.

I'm comfortable with the panel adhesives, a shop I worked at built an airplane out of carbon fiber and used adhesive to piece it together. Very common in aviation so the strength is there.

It'll take a while for the panels to arrive from the Netherlands and work is pretty busy right now so it could be a few weeks before I'll even have time to deal with it.

I've glued about 10 things in the past couple years. One was a roof skin which really worked out well. I did partial patches to sections of quarter panels. Make sure everything is ground down well and DO NOT CLAMP the repair patch too tight because too much glue oozes out and works against what you are trying to do.
Let's say you glue in a patch. How do you intend on sealing or covering the edges of the new patch with the existing panel? Henry

[Len]

Fusor advertises that they have "bond line control" but I still think you may be able to see a slight line under the right conditions. However, if the patch is low on the car or the car is a light color you can probably get away with having a seam run across the face of the panel. Fusor also has crystals in the adhesive that act as spacers and allow you to clamp it tight without squeezing all the adhesive out of the seam. If the seam is on the face of the panel grind off all the excess adhesive then apply a fiberglass filler over the seam and regular bondo type filler thereafter if needed for further leveling.

Link

[ol'volvo]

I was going to go over the glue line with All-Metal and then business as usual with filler etc.

Likely what I will do is attempt some welding as others have suggested in other threads on a junkyard body panel and see how that goes. If it seems like it would take me too long to get the feel for sheet metal welding then I'll drop back and glue.

The car is going to be painted a light cream color so apparently that works in my favor. Also I don't plan on doing a clear coat, want the gloss to look more "factory" for a sixties car so that may help too.

[cully1]

We "glue" on a lot of panels in our shop...1/4's, roofs, etc. etc. On sail panels, where the 1/4 goes into the roof, or any other area that will show.. we still weld solid. You will see a line "ghosting" eventually if you glue instead of weld. I know there are shops out there glueing these areas and the bond is very good and if done correctly won't fail BUT you will see the line eventually no matter what you put over it. For patch panels like you are going to be doing, it's best to weld solid if you don't want to see lines later on. Cully

[Iceman]

We "glue" on a lot of panels in our shop...1/4's, roofs, etc. etc. On sail panels, where the 1/4 goes into the roof, or any other area that will show.. we still weld solid. You will see a line "ghosting" eventually if you glue instead of weld. I know there are shops out there glueing these areas and the bond is very good and if done correctly won't fail BUT you will see the line eventually no matter what you put over it. For patch panels like you are going to be doing, it's best to weld solid if you don't want to see lines later on. Cully

Mine looked good through the mild winter we had, now that it has turned cold (2 degrees F) I notice a line this morning. After all that work! Time to weld! I guess if you were doing a whole skin it would be fine, but I'm not convinced for partials with exposed lines.

[ol'volvo]

I'll glue if the seam can be hidden under trim but looks like welding is what I'll have to do for repairs in the "field" of a panel.

Having a line show up after all the work is what I was worried about and looks like welding is the only way to make sure that doesn't happen.

I know some do a combination and that may still be an option to take advantage of the corrosion fighting properties of the adhesive.

Time to practice welding.