View Full Version : best way to install new floor pans

07-04-2008, 01:33 AM
what is the best method for installing new floor pans?

i have welded in new panels but have heard and seen people install panels and rockers with the 3m panel glue i have heard many good things about this glue but have never used it myself. i could see it being extremely effective on keeping the rust from forming between the panels and you don't have to worry about warping from welding.
any advice or other comments

Kevin Phillips
57 Silver Hawk

07-04-2008, 05:36 AM
The only correct way is to WELD the panels fully. Don't let anyone talk you into bolts, screws, pop rivets, fiberglas, or glue... in fact I've never heard of any adhesive that could bond metal panels in; sounds more like a seam sealer. Not only would that be a poor way to put in metal, I can't see how it would last long enough to make a trip around the block...

If this was a raggedy 4 door Lark you were just trying to get a few more miles out of before it was scrapped, maybe rivets or screws would get you a little time; but your car warrants doing it right, rather than having to do it over in short order.

Robert (Bob) Andrews Owner- Studebakeracres- on the IoMT (Island of Misfit Toys!)
Parish, central NY 13131

"Some people live for the rules, I live for exceptions"- 311

"With your Lark you're on your own, free as a bird, alive as a Lark. You've suddenly discovered that happiness is a thing called Larking!"

07-04-2008, 07:30 AM
The front floor pans in your car can sometimes be so important that the sturcture depends on it(front let and right) I don't think glue would do you any good. I had to replace both and some welding had to be done to the lower hinge area which is usually damaged.:Dgood luck

Studebakers forever!

07-04-2008, 09:13 AM
The panel adhesive you heard of is called Fuzor, a 2 part adhesive, applied with a dual gun. This stuff is very good, very $$$ and used in the auto industry currently. It is used where panels overlap and can be pressed together, after which, when cured, cannot be pulled apart, before the panels tear in a different location. The stuff has a very high shear strength.
This type of technology does not apply to repairing a floor pan though. There's no way you can apply the material or a press to this area, in the manner needed to accomplish the goal.
Depending on the intended quality of the repair, replacement floor pans have to be matched to the opening, then cut to fit, temporarily attached, then welded in place.

Bob Johnstone
55 President State Sedan
64 GT Hawk
70 Avanti (R3)

07-04-2008, 11:55 AM
In the areas where you welded the new floor pans, get some "Gorilla Hair" body filler. Very difficult to work with as it is extremely stringy. apply it all around the underside of your new floor patches. If you can try and make it flat without any if it dripping/hanging down. Once it is cured, you will have a rust proof floor installation.

I would also apply some to the areas around your welds inside the car, and then you can grind both the weld and the filler down to form a smmoth transition.

Gorillia Hair is one of the truly water proof body fillers. Once you add the catalyst you have about 90 to 120 seconds to appply it.

07-04-2008, 12:29 PM
Me thinks that this issue was covered several weeks ago in another forum. I believe that the majority view was to weld. I agree. I've used the SEM patch panel adhesive that I would guess is much like Fuzor. A couple of friends in the body shop business use it also. It works well in their applications, which are generally patch panels that are also lightly tack welded to provide better hold. I'm sure it works for a few years.

I'll draw two conclusions from my experience:

1- The first tube I purchased had a small hole in the bag. When I made some test panels, the material would not cure. After two days, I took the remainder back to the store and they replaced it. I then used the new material and did some rather crude lap shear and lap peel testing. Amazingly great adhesion.

2- The reason that I would not use it in areas like floors, etc. is that any lap joint has the possibility of either permeation or capillary action into the joint. If any corrosion happens at the adhesive/substrate interface the joint will be compromised. I cannot think of an area more prone to this issue than the floor boards. While GM may use the technology for panels, I'd like to assure myself that the floors I installed will be solid long into the future.

My bottom line is that with the sensitivity of the material to aging prior to installation coupled to the potential for long term failure and the absolute knowledge that a welded joint will last as long as the steel, I'll continue to use my MIG for these type of panels.

07-04-2008, 05:39 PM
Great looking job on those floors. I can't imagine why you would have any trouble at all with stitch welding and using an adhesive in between. The adhesive will also act as a sealant too, so that issue is remedied. It just looks fabulous.


07-04-2008, 06:11 PM
IF you glue then weld, you'll burn the glue. IF you do glue, then mix some fine particle sand in with the epoxy so that it won't be squished out completely in any spots causing weakness. Just listen for the sand crunching as you tighten down the tiny bolts. If you do use tiger hair, just cover it with cellophane before it sets and smooth it out by running your hand over it. When it's dry just yank off the cellophane, leaving a very smooth surface. I can understand the frustration with welding. If you don't have a pro to show you how then the trial and error method can become bewildering very quickly. I just ordered a new mig welder that can go down to 22 amps. The top is 130 amps. ($350) I'm going to try it first with flux core wire then go to solid only if I have to. I've used many different welders heat ranges wire sizes wire speed, butt welded lap welded set the shop on fire, etc; but only now do I believe I might have the solution to forming clean butt welds in sheet metal.

TX Rebel
07-04-2008, 07:18 PM
Butt welding takes more labor to fit, and can be very unforgiving, but anything else is patching, not restoration. I prefer to torch weld butt seams. It takes more time & patience, but is stronger, better looking, and requires less grinding.

Barry'd in Studes

07-04-2008, 07:57 PM
If I remember my basic MIG welding correctly, flux core wire runs markedly hotter that solid and is not generally recommended for sheet metal. My Century 160 amp gas MIG runs at 1-2 on heat on a 5 scale and a heavy 2 on wire feed with .023 wire. You can run all day at those conditions and make nice welds, and my welding training is hands on. The best investment I made was a large faceplate auto-darkening helmet. The best way to weld sheet metal with the above is to butt weld with a slight gap, dang slight and clean metal. With practice it's quite easy. I would like to be able to gas weld sheet metal as it makes a softer weld and easier to finish but don't have the touch.

52 Ragtop
07-04-2008, 08:07 PM
There is a 2 part epoxy "glue" that is used in collision shops. There are several manufacturers, 3M, and Kent are the 2 that I always bought. A couple things; Glues are NOT intended to be the only means of attachment, 2; the surface's that are being glued, MUST be clean, no oil, dirt, paint or primer!
BMW's now use an aluminum frame rail that is glued and pop rivited to the steel body, per BMW, the "special" BMW pop rivit must be used, or the structural integrity of the frame rail will be compromised! (must use BMW glue too) The rivits are $2.25 each, I forget how amny it takes, but it's at least $100 worth of rivits and another $50 for the glue.
I would recommend welding in the floor patch panels by flanging the original floor, fitting with sheet metal screws, then welding it up. Etch prime the area, use a 2 part seam sealer on it working it in with an acid brush. Be sure to seal seal BOTH inside and under the car!Again, etch prime, paint and undercoat, or better yet, use the bedliner sray in a can form your local FLAPS.
When welding, you could also plug weld the panel in at 1" intervals. We have actually, glued a beemer 1/4 on over the wheel opening, and welded through the glue before it sets up, looks and "collapses" the same way as factory when involved in another collision.
Welding through the epoxy glue takes a LOT of practice to get it right.


Mike Van Veghten
07-04-2008, 08:47 PM
Many "new" cars (BMW, Mercedes Benz, etc.) have many "bonded" joints in them.

Most all modern aircraft...have mostly bonded panels that are lightly rivited. Only (in general) engine and landing gear structures are bolted.

On the other hand...as has been hinted at or mentioned...if it were mine, I'd want butt welded floor panels. As my two Conestogas will get as required!