Using an epoxy glue for structure

I vote for welding it whenever possible.

Keep in mind that the strongest epoxies anyone makes have a tensile strength of only about 3,000 to 4,000 psi. While ordinary low quality steel might have 40,000 psi tensile strength or more, so you need a pretty wide area of overlap to get a good strong bond. If you pull hard enough on a panel, the epoxy will probably de-laminate before the steel tears.

I don't think I would want my seatbelts or roll cage anchored to a floor that's just glued in with epoxy. I doubt if any racing organization would let you race something that has the floor glued in if the seat belts anchor to the floor.

To me, epoxy is a way to put cars together cheaper and with less labor. When they use it on new cars, they have to do a lot of engineering to make sure there's enough bond area in the right places. When people glue in patch panels, they're probably not putting a whole lot of engineering time into it to make sure it's going to hold up in the long term.

 

I have a new C6 corvette and when you look under the car you I think this how they installed the floors from the factory. There are cross supports under the floor that you can see the adheasive squeezed out. This also the same way my C5 corvette was built.

I would say if this is the same way the manufactures build cars then you should have no problem.

 

heres a thought..
If you paint the panels first, the glue is sticking paint to paint...If your paint adhesion to the steel is not spot on, thats what will let go, not the glue. I would lightly blast the panels first and use a compatible paint system, or the whole lot will just rip right off with any twisting in the subframe.
I guess this is another 'weld it' opinion..

 

Plug weld the **** in, cheaper, easier,less h***le and stronger as reported.

 

thats because they hadn't invented it yet. i've tried to take apart oem panels put together with this type of stuff and it's nearly impossible. when people think epoxy the first thing that comes to a lot of peoples minds is the stuff in the tube they sell at walmart, this type of epoxy has been engineered specifically for bonding together panels in cars. extremly tough stuff.

 

Actually I am leaning towards using the PS-890, which is an aircraft sealant. I will coat the bottom of the panel and also secure it with stainless steel blind fasteners. That way we have 2 modes of retention plus all of the bolts that hold the seats, body mounts etc.

Oh and that roll bar and the seat belts won't be attached to the skin. The roll bar is welded to the structure and the belts will have tabs welded to the roll bar.

 

Let us know how it works. I am interested even tho I think the pros lean towards welding in all but your situation.

 

i say go for it. those adhesives your talkin bout work great. i would seal the seams as well with some of that seam filler.

 

A little o/t, your corvette has balsa wood floorboards sandwiched between two pieces of smc. Works wonders for sound deadening. On the glue, I use 3m panel bonding adhesive for glueing roofs and quarter panels on. I have also used norton's panel bonding and it works very well too. 3m states glueing is 4 times stronger than welding and warrantys the repair too.

 

Isn't this glue **** so they don't have to pay people who know how to weld? The comparison of the corvette doesn't really jive with me. take a look at the corvette it's a bit different.

 

Yes, all of that, I see the floorboards as structure, in all directions. Without that, the body has more of a chance to collapse in a crash from combination of bending/twisting/compression forces. A new roll of mig wire costs sixty bucks. After doing the floor you'll have enough wire left for a hundred more sets of floorboards. With glue, in a rollover, given the tremendous disparity of strength ratio of glue:welding, the strength factor and the cost are both deal-breakers in my mind.

 

From what I've been taught...welds are better for structural, and panel adhesive is good for door skins, modern bedsides, etc...primary design is to save time, since modern body shops are more production oriented.

 

Love the pic. The floors are glued. On the z06, the frame is aluminum. Been to gm school on them.

 

I have glued door skins, quarters, roof panels, bedsides etc on with either 3m panel bonding adhesive, or Lord Fusor products panel bonding adhesive. The only thing that i know will seperate the glue is heat and crashes. It is very common place to "glue" panels on these days, but i welded my floors in on the Olds.

 

Nortans Speed Grip. GOOODD stufff

comes in 1,10, and 30 minute setup time.

 

So I got curious and looked up the specs on Nortons Speed Grip. It has a tensile strength of 3700 psi which is about the same as a lot of epoxies you buy in a 2-part tube. Nothing special as far as epoxies go. Then I looked up the tensile strength of Lincoln's ER70S-6 Mig wire, which is one of the most commonly available wires used for general purpose steel welding, and it has a tensile strength of 70,000 psi.

So 70,000 vs. 3,700. ... and the winner is WELDING.

If I bought an old car from somebody and found out the previous owner had put it together with glue, I think I'd be pretty pissed about it. I think gluing it is just a shortcut to doing the job right. Just like patching in holes with bondo and newpaper or painting over rust. Sorry, but that's how I think of it, and I'm sure most guys into old cars would feel the same way about it.

 

BINGO! The right answer for most folks...........but notice the subframe Root has in this car. I am a fan of welding but this coupe is more of a drag car with a steel subframe on steroids that the floors will simply stick to. In many other drag cars they would be held in with Dzus fastners, what he is doing is overkill.

 

I'm gonna put in another vote for welding... What if you ever need to get the floor out for some reason, driling out a bunch of spot welds will be a lot easier then trying to heat and peel the floor up.

 

There is nothing structural about the floor pans he is putting in. They are purely a cover over top of what is a more than adequate substructure. The strength of the glue is going to be more than adequate to hold them in place and will actually result in a much more corrosions resistant final ***embly. If the floor panels were structural I would agree they need to be welded in but they are not so the arguement really is incosequential.

 

That stuff wont let loose, it seems a bit sketchy, but its sposed to be stronger than welding, i know this because im out one pair of small needlenose vice grips...got a bit on them when it was clamped and dried..oops. Make sure you have a very good grind on both mating surfaces. But instead of one small weld every 2-3 inches you have 50 times the surface area of bond. Its not gona come off. The 8115 is great. And you have corrosion protection between the 2 panels then also. Which is a huge reason i love it.

 

Ok Root, how did it work? What did you use? I am looking at a combination of fasteners on my Tudor floor, frame.............think Alex's car

 

Come on man weld it seam seal it and paint it.I don't think it is a good idea for floor boards.I am a body tech and use the adhesives a lot on the new car junk but floor boards are exposed to a lot of heat from engine, exhaust and road heat. heat destroys adhesives,not good. I personally would not do it.

 

It worked awesome. The floors are as tight as a drum skin and not rattle. Byt the time I get the dynamat down it will work out perfect.

By the way low lid dude. It's a done deal. I didn't use the body shop stuff, I used aircraft grade sealants.

 

Got a brand name and source?