Quarter panel adhesive instead of welding?

I was asked a question about 3M Impact Adhesive being used to just glue a quarter panel on a car. I did not know the correct answer. I know that I weld and spot weld them back on a car. Only using glue where it was before the removal. Would a quarter panel stay put if you didn't have a welder. Glue the sleeves in place. Then glue all the seam, Vice Grip all together. Let dry over night. Unclamp in the morning.  Sand the sleeved area ,fill with body filler. Prime and paint reassemble and away it goes.  Is it acceptable repair now days with these advanced adhesives?This car was welded. It is just an example photo.

I have used the 3m products to hold wheel tubs to truck bed sides with no problem. If you look at the specs it has something like 4000 psi/sq.in adhesion strength.

They recommend welding in certain areas when using panel bond but it is my go-to process first when I'm looking at body work now. No heat, no warping.

I use spot weld along with 3m panel bond adhesive. I think 38615 was the last one I used. Basically I laid a seam of panel adhesive, clamped it, and followed up with a spot welder while the adhesive was still in its workable time. I have only used panel adhesive for the last few years and honestly I think it's better than welding and seam leading like I was originally taught. Much less distortion of panels. 

Both answers are what I do. Glue and spot weld. It helps keep water out of the seams. Lowers the chance of rusting.

I have been tipping towards the adhesives for a while. They avoid warp and remediation work on long seams like lower-quarter panels. They also seal the seam to avoid future rusting.

When you do a spot weld or a long seam weld, the backside is by definition oxidized metal because there was molten metal reacting with oxygen outside of the reach of your shielding gas. If you can not get to the backside to clean and coat the surface, then your project already has a start to the rust returning. Spot-welding lapped panels makes this worse since it also leaves places for moisture to accumulate.

The only downside to glue is that I cant make an invisible metal-finished repair. The glue demands a lap joint and that will be detectable from the rear and require filler on the front.

I used rivets with panel adhesive, you can see how I did it here:

https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/minimum-viable-product-96-miata-bodywork-on-the-cheap/178879/page1/

One thing that is cool is the harbor freight flange tool:

https://www.harborfreight.com/air-punch-flange-tool-1110.html

That'll give you nice edge that's recessed a touch as well as a beautiful hole for a rivet so it's not all mangled like drilling sheetmetal can do.

When replacing aluminum quarter panels you use panel bond and rivets to secure the panel to the surface. Turns out nice and no welding. That is how aluminum besides are attached. I purchased a air rivet gun to finish the last one I repaired.

How about joining fiberglass flares to steel? Would Panel Bond be the best choice?

Unibody: a single molded unit forming both the bodywork and chassis of a vehicle.

If you don't weld it and rely on glue for the strength of the unibody...well, good luck to you.

In reply to MuSTANK :

Absolutely. Dig around on the 3M panel bond pages and you'll find all kinds of bulletins on best practices for different uses.

In reply to Wicked93gs :

I like that reply. It is a structural part of the car.  

As far as fiberglass to steel. I was told by coworker that panel bond does not stick to fiberglass.  I would try a test piece and used an epoxy that is ment for steel. Like JB Weld. And see how it adheres.

In reply to jgrewe :

Thanks for the info ! ! I was originally thinking of using fiberglass resin, but the strength just isn't there, kinda of scared/uninformed about Panel Bond, but I'll scope out the bulletins for sure ! ! 

I wouldn't be so dismissive of adhesives because of the structural usage.

I was under the impression the Lotus Elise (and other modern aluminum Lotuses) were glued together. See also the field of modern composites.

It's not like we're talking about library paste here.

I'm still of two minds largely because I have weird misgivings about what the *next* restoration will be like when trying to prep for a new panel in another 30 years, trying to prep a mix of metal and adhesive.

The removal of the old Adhesive is not a problem. Drill out the spot welds. Then use a heat gun or Propane torch to heat the area that is glued. It should separate easier after heating. You may even hear a popping sound. Then you can grind it with 36 grit/orange wheel it clean.

Here is a answer that came into the shop. It is a BMW that has been rear ended. It needs a new rear body panel. The BMW direction for replacement read. Glue and pop rivet (2 different types) no weld. Yet the rear panel is spot welded in place at the factory.

That is the bag of pop rivets that came with the glue.

Jesse Ransom said:

I wouldn't be so dismissive of adhesives because of the structural usage.

I was under the impression the Lotus Elise (and other modern aluminum Lotuses) were glued together. See also the field of modern composites.

It's not like we're talking about library paste here.

I'm still of two minds largely because I have weird misgivings about what the *next* restoration will be like when trying to prep for a new panel in another 30 years, trying to prep a mix of metal and adhesive.

The problem is not the strength of the adhesive(after all, JB-weld is an adhesive and plenty strong). The problem is that adhesives work off of chemical reactions and regardless of the adhesive used, they ALL have one common weakness: heat. Enough heat will break down ANY adhesive over time. Now, the question becomes are you willing to trust that a car painted black sitting out in 120 degree heat in the sun isn't slowly breaking down the adhesive and compromising the structural integrity of your car? Yes, I am aware aluminum bodied cars are generally glued together(lord knows why when there are such things as TIG welders) but most of those aluminum bodied cars are either not unibody cars(F150 as an example) or are not cars that see a lot of weather(Acura NSX). Honestly I am not sure why anyone would ever use panel bond anyway when spot welding is so easy.

Our Classic Motorsports Bugeye project has a glued-on quarter: