I am toying with the idea of filling the body cavities/voids with an expanding poly foam like Great Stuff to aid in thermal and sound insulation. The only down sides of this, that I can see, are if a leak develops, the water will not drain out, and if I want to run wires after the fact, it would be more difficult.

Any thoughts?

My aim is to make the car ride more quite (less wind noise/resonance) and for the A/C to be more effective. This will mainly pertain to the voids in the roof rails, B-pillars, C-pillars, etc. I am thinking of using good sheet insulation in the doors, under the carpet and between the roof and headliner.

_________________
Restoring Wife's Great Grandparent's 1963 Dart.
Built August 30, 1962 in St Louis
First month of production
Serial Number 599
Still is a basket case.

Great Stuff is good for insulation purposes (heat/cold), but it has the problems you mentioned AND you have to account for the fact that it expands to about three times its original volume.

Check out:

http://www.sounddeadenershowdown.com/

This is a comparison of the major Dynamat-type materials on the market. You can read it all or jump straight to the conclusion to make your pick.

I've used that foam to fill gaps in some sheet metal repairs and it seems to be holding up fine; it took longer than I expected to reach full volume, so be sure to experiment a bit 1st.

Also, just a work of caution - I would be wary of using that foam near anything that might get very hot or burn - it may produce nasty fumes.

I haven't used foam in cars, but have in some other applications. Just a couple of thoughts:

This stuff is sticky when sprayed, and a PITA to remove when cured. Mask well. Allow for removing the excess that WILL squeeze out.

When filling flotation chambers in a canoe, I put the foam into a trashbag stuffed into the cavity. I don't think that would work in the pillars, though. Maybe newspaper rain bags?

Regular Great Stuff expands a LOT, and can exert surprising force - maybe enough to distort the sheet metal a bit. In the smaller areas, this wouldn't be a problem. I'd consider the versions that expand less, those intended for use around windows, etc.

For future upgrades (wiring), how about encapsulating a plastic channel or tube in the foam through those areas?

Let us know what you do, and take some photos!

_________________
"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

Hi,
I just did some quick and dirty body work on one of the vans at the food bank where I work. I was going to use Great Stuff but found that it holds moisture like a sponge.So,I looked a little more and found another Great Stuff product,specifically for ponds and waterfalls. It's waterproof,tight and expands much less than the original product. I really like the way it worked. You can saw off the excess with a hacksaw blade or similar tool and the rest of it can be shaped and sanded with a flapper type sanding wheel that fits on your drill. It IS very sticky and flammable while working with it.Hope this helps. Dan

exactly.

and so does anything that interferes with moisture drainage and air circulation. if condensation develops in any of the pockets that you filled or covered over, your car will rot from the inside out and having to remove the filler material will add significantly to the repair costs.

i no longer have the link but once upon a time there was a couple who decided to do exactly what you are planning to a VW microbus. they crammed about 300lbs of expanding foam, dynamat, koolpatch and rigid insulation into every nook and cranny they could, and explained every insipid detail in a very grandiose and self-satisfied manner. what the site did not reveal, and was uncovered by a few industrious members of the VW community, was that less than five years later the bus was scrapped because it was completely destroyed by rust. the rust was in some very unusual and structurally critical areas of the bus. someone found it in a junkyard and took photos, and posted it in an online forum.

dont be the next one.

_________________
I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

This thread's very interesting to me. My truck's cab ('89 Dodge D100) is utterly without insulation, and the roof and pillars in the sun turn the cab into an oven. The A/C doesn't stand a chance of keeping up. If it's hot and dark out, the A/C works great. Hot and bright, the A/C scarcely makes any difference. I was thinking of polyurethane foam for the space between the two roof panels and the pillars, all of which are easily accessed for squirting in the foam, but:

1. I've never seen the special pond/underwater variety. Does it have a product number or specific name?

2. I don't want to create rust problems.

I'm not too worried about rust since I wouldn't be using the stuff anywhere below the truck's beltline.

Oldiron36: See Lizardskin.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

I soundproofed the cab of my '73 D100 with a generic version of Dynamat. It made a huge difference!

I covered every bit of sheet metal and even spanned the open holes in the doors, kick panels and ceiling. Then I used soft fabrics for all the upholstery and put an extra layer of jute padding under the carpet. It used to be very noisy, but now it's nearly as quiet as a new $40,000 truck.

The Great Stuff web site claims it is weatherproof, but who knows. They say that the latex-based foam is just like a sponge, and it will probably rot out a car fast. The GS is a closed cell poly foam, and should be weatherproof, at least for the short term.

OK, If the GS is out, waddya think of using some sort of polyester batting like used in sleeping bags/quilts/coats? It would have the advantage of being able to breath, but may also wick liquids and become a mess.

Another thought is to fold and cram sheets of insulation into the voids. A lot less permanent then the GS foam.

_________________
Restoring Wife's Great Grandparent's 1963 Dart.
Built August 30, 1962 in St Louis
First month of production
Serial Number 599
Still is a basket case.

The topic of automitive insulation for heat/sound purposes has been beaten and dissected to death over on vannin.com Do a search or see HERE

I am currently installing this:

http://www.carinsulation.com/index.php

The price tag was good, and it's lightweight, it doesn't absorb moisture either. Seems like it might be good cheap insulation.

about the most non-intrusive way to minimize solar heat gain in your cab is to tint the windows with a low-e coating and unfold a reflective cardboard panel (AKA sun shade, sunglasses print optional) inside the windshield when you park. it does not have to be a deep tint to have maximum effect, blocking of uv rays is key.
dark interior/exterior colours tend to absorb more heat as opposed to lighter colours, if you can find something light-coloured and tasteful to throw over your seats on the hottest days you may notice a nominal difference when sitting on the seat.

OP, this strategy combined with a thicker carpet underlay and a parallel-flow AKA manifold-style AC condenser will reduce noise and heat without reinventing the wheel and causing nightmares later on.

_________________
I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

Did the foam thing on my 71 Maxi-Van. Now looking for a fiberglass top for it. Every spot I used the expanding foam has developed rust through spots.
This on an old van that went 36 years without any serious rust problems. If I had it to do over I figure something else or just live with the noise.

_________________
66 Valiant, 225.
84 Van, 225.
71 Maxi-Van, 318
60 Valiant wagon, 225
87 Maxi-Van, 318 4spd

If you do decide to use A/B (expanding) foam, a word of caution; if you're filling a confined space, fill it in small batches (easy enough to put in more if it's not full enough). Even if unconfined on one side, It can develop a huge amount of (potentially destructive) force. Case in point; We used A/B foam to insulate an icebox in the galley of a sailboat and inadvertently overfilled the cavity a bit. Came to work the next day only to find the surrounding cabinet broken and the fibreglass icebox insert crushed like a pop can.

Nat

_________________
1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

When I had my 78 D 300 the cab was pretty solid except for the floorboards. I cut out the real bad stuff and MIG'd in some sheetmetal over it; Only the drivers side floorboard was bad the pass side had a few pinholes. So I hand laid fiberglass cloth over the whole entire floor pan. to seal the pinholes that were left and the gaps between my inch long (or so) tack welds. I was really surprised the difference in how quiet it got in the cab! I could hear the gas in the in-cab gas tank sloshing around real good then! I've also seen my buddy's Little Red Express, which he completely redid, and in the process, had the whole bottom half inside the cab Rhino lined, about a 1/8"-3/16" thick layer; that stuff comes in several colors too, if you would want!