Using Expanded Foam

[Bill D]

I would like to fill the empty space between the inner and outer glass parts on the spider roof for added strength and sound deadening. Can I do that w/o damaging the spider?

Thanks
Bill D

[Russ Noble]

Depending on your definition of damage, Bill!

Unless there is a hi-tech way devised for injection you're obviously going to have to cut several holes in the spider somewhere because it's an awkward shape to fill. If the fibreglass is fairly thick you may not get much distortion. If the inner is thinner than the outer then the distortion will probably be confined to the inner.

Cheers,

Russ

[John W]

Bill, if youre going to use squirty foam ensure the panels don't get pushed apart !!

I'd suggest drilling a few holes, and filling from one, allowing it to expand out of the others.

I panelled and filled the back side of a garage door some time ago. I didn't make the expansion holes big enough on the first one, and it pushed the panel out considerably
The key is to not underestimate the extent to which it expands...

[David Morton]

AND - it's incredibly messy and notoriously difficult to clean off.

[Brian]

Bill, get the low expansion stuff. They have two different kinds at the hardware store. I have been using it to fill voids and I like the results. HORRIBLY messy though, and it's just as much of an adhesive as it is a filler. Mask everything in advance rather than try to clean up afterwards. However, the stuff is cheap enough to experiment with in regards to expansion rates and using different tubes to pump it in. I'd make a cardboard model and use a long tube to pump it in deep into a void to see how it works in regards to expansion and fill capabilities.

I have not done my spider, but will cut holes in the door jambs when I do the same.

Brian

[Bill Hough]

Bill, the hardware store stuff is really not the best foam to use. In it's cured form, it stays soft anf flexible not lending any strength. The two part foam supplied by composite supply houses would push the two panels apart for sure. It would have to be done in a mould with strong clamps, and a really beefed up mould. I used to work for Boston Whaler Boats and I would see the moulds blow apart sometimes shortly after the foam was poured in. These moulds were built like army tanks. This type of foam expands with the same force in all directions. I saw picture somewhere of Fran standing on top of one of his roofs showing how strong they are. Proof to me you don't need anymore strength in the roof.
...

[Bill D]

Thanks guys. Instead of expanding foam, what about some type of liquid (hardening) insulation?

[Bill Musarra]

Bill,
I recently wrote an article for the GTD club on paneling and other operations which included a section on insulation, which covered all types of insulation from the mats to the expanders. I can send you the full article if you are interested. What I wrote was the following about the expanders.

"A cheaper more labor intensive alternative is to consider the insulating foam sealants used in the building industry. Names like Great Stuff comes in aersol cans at most building supply stores. NTAP X-30 Polyurethane Foam, is a 2 part pourable foam expander. When mixed 50/50 A/B by weight, the mixing time is 20-30 sec. with a rise time of 2-3 min. It is tack free in 3-10 min. with full cure occuring in 24 hours. This produict is best done in several small pours rather than one big one. Fomofoam, a two part spray for verticle surfaces, comes in propane type containers. All form airtight and waterproof seals, bond to most materials, cure rigid, and are easily trimmed with an electric carving knife etc(for open tube frames). Just be aware that they can be messy, as they are very sticky. If the surface or adjoining surface is a paited surface, it should be covered with "plastic wrap" from the kitchen drawer and taped in place. All holes and gaps should e taped closed unless used for the expansion of the foam. But remember this stuff is expansive and will push things our of its way if there is no place for it to go. If you have double layered panels, it is a great filler and insulator. Just give it an escape route for accidental over filling. If it does get on the aluminum or stainless, solvents/cleaners/polishes or elbow grease will bail you out. If used in the central tunnel, block off the cooling pipe holes or cover the pipes. Wrap all wires, cables, etc. in some form of PVC piping or kitchen wrap. Be sure to line the tunnel cover with the kitchen wrap so that it can be removed for repairs. Remember this stuff bonds to all surfaces.

Mixing two liquids, a polyether polyol and a polyfunctional isocyanate produces polyurethane foam. Like all organic material, when they are exposed to an ignition source with enough heat, polyurethane foam products will burn. Even the most flame retarded urethane foam will undergo combusion at temperatures exceeding 550 C(1022 F). This is a hazard to be considered. Having said that, one must remember that the fiberglass that surrounds us is also combustable."

This doesn't cover all the materials out there. Do a Google search for foam insuilation. Just take your time if you use the pourables, use a lot of tape to secure "handyWrap" on the "show" surfaces. If you use the spray type, drill holes just large enough for the spraytube to enter the void at about two inch intervals across the surface, with a larger hole at the end of the panel for escape. Be sure to give it some place to go. If you plan on putting leather or some other fabric on the panel, all will be hidden. I used it on almost all of my stainless paneling and it was a breeze. But them stainless is a "little" stiffer. Had to do a little clean up, but wasn't that difficult.
Get some thin shipping boxes from the post officeand try some of it, and you will learn real fast how much goes a long way, and how hard it pushes on the surfaces as it expands. When done you will notice that the doors will shut with a dirinte solid sound, and the interior of the car eill be much quieter. Fewer surfaces for the sound to reverberate off of.
Need more info or would like the article let me know.

Bill

[Bill D]

Thanks Bill

Do you want to email, PM or snail mail it?

[Fran Hall RCR]

You really do have to love this forum........what great wealth of knowledge and detail this place is.

[Gregg]

Daytona Bill, I remember that picture of Fran. I'm not so sure it was him though. Looked more like an anatomically enhanced blow up doll.

[Dean Lampe]

I feel a bit silly asking this question but why do you want to do this? Just curious as my car will be ariving soon and will try my best to follow in your foot steps.

[Brian]

With me it's strictly for sound deadening. Accessable areas are done with foam board/Dynamat or similar materials. If I were going to try to increase strength, I'd investigate a different route.

Heat protection is a different can of worms.

I'm probably adding 30 pounds to the car, but I want it sound SOLID when you slam the doors and drive it around..

Brian

[Lynn]

Dean,

I am with Brian on this one and I'll tell you why. I was watching one of those test drives on Speed and I think it was for a new Audi at the time. They were summing up and the guy being interviewed said, "........you could possibly build a car that performed as good as this car, but then you'd have a rattly, noisy kit car........" But, I also had heat in mind so that there would be no question that the A/C would work and the car wouldn't be drafty when it was cold.

At that point, I decided that my car was going to have a solid feel and sound to it. No rattles, vibrations, squeakiness would be allowed. (Also see the post I just made on Spraying inside of fiberglass.) I used dynamat extreme in visible areas, I used a layer of high temp mastic with a layer of closed cell flame retardant polyethylene foam under all the carpet (including interior side of the firewall), aluminized silicone fabric was used directly adjacent to the engine/headers and aluminized blanket was used elsewhere in the engine bay. I also used rubber gaskets or closed cell foam tape on all access doors and contacting surfaces. The only reason I didn't fill the tunnel was that I thought it would be better to allow the air to flow through to remove any heat escaping from the insulation wrapped coolant pipes. I didn't foam fill the doors so that I could get to the door latch mechanisms if need be, but the I did use high temp mastic against the interior of the fiberglass panels and then filled all the voids and covered everything over with foil backed fiberglass batting. Everything was then sealed off with aluminum tape. The door pockets are all formed with lauan and lined with foam backed headliner material as well, so they sound solid when shut. Blocks of closed cell memory foam were also sculpted to seal the doors, from the sills to the windshield surround, just behind the hinges as well.