[steweddude]

I am building a Studebaker street rod. It is currently stripped down with just a coat of epoxy on it. I have toyed w/ the idea of spraying the interior sidewall and possibly the roof with spray-in foam insulation (similar to Great Stuff in aerosol cans but an industrial two part variety). I see the advantages as sound deadening, insulating and also displacing areas where dirt, water, gravel have migrated to in the past and sat until rust developed. I considered lining the body cavity w/ plastic so if it became necessary to remove the foam in the future, it wouldn't be stuck to the body and make a huge mess. Has anyone tried this? Would you do it again?

[a1supersport]

That's sounds interesting...especially for sound-deadening. Older cars have a lot of air-space in between inner/outer body panels, as well as between inner panels/interior pieces. Is this the same stuff they use in house walls/ceilings? Where, as you're spaying it, it expands and fills in gaps?

[steweddude]

Yes, it is the same stuff that they are using in new housed now. In my 50 Studebaker I probably have 4" of unusable space in the center of the doors which would taper down to about 2" at the rockers and the top of the car.

[CDJr]

I sprayed the inside of the door panels, quarterpanels, floors (both sides), and trunk area of my 68 Firebird for sound-deadening, protection, insulating, etc....but I used a spray-on bedliner. It doesnt fill in the dead space but its permanent and will give the car a more solid sound as well as definitely prevent rusting

[DanTwoLakes]

Spraying in foam insulation may work temporarily, but there are a couple of disadvantages. The first one is that if you have ever used Great Stuff you know that there is no way to control it after it is sprayed in. The second and most important thing is that after you drive the car for a while the insulation will loosen up and squeal like a baby pig as it rubs against the metal shell of the car. BTW, after you fill your doors up with this stuff, how will you raise and lower your windows?

Use something that others have used, like spray on bedliner or Dynamat, and avoid ruining your car.

[slodat]

I did a very elaborate car audio installation in a 2003 Mustang. The trunk lid is made of ABS plastic or something similar. The inner support structure is bonded to the outer lid piece. The subwoofers were causing a lot of rattles in the trunk lid. We filled the voids with the spray foam as you mention. It **looked** like it was working out well. As Dan says above, you have no control over the foam once it's out of the can. We put more foam in one of the passages than it could hold. The result was a couple of very ugly bumps in the outer trunk lid. Which cost a lot to replace..

[LATECH]

Originally Posted by DanTwoLakes

Spraying in foam insulation may work temporarily, but there are a couple of disadvantages. The first one is that if you have ever used Great Stuff you know that there is no way to control it after it is sprayed in. The second and most important thing is that after you drive the car for a while the insulation will loosen up and squeal like a baby pig as it rubs against the metal shell of the car. BTW, after you fill your doors up with this stuff, how will you raise and lower your windows?

Use something that others have used, like spray on bedliner or Dynamat, and avoid ruining your car.

A lot of foam like this is also open cell which holds moisture when it gets wet. I would not think it is a good Idea. Why not do the bedliner thing or how about Dyna Mat like DTL says

[LATECH]

Originally Posted by slodat

I did a very elaborate car audio installation in a 2003 Mustang. The trunk lid is made of ABS plastic or something similar. The inner support structure is bonded to the outer lid piece. The subwoofers were causing a lot of rattles in the trunk lid. We filled the voids with the spray foam as you mention. It **looked** like it was working out well. As Dan says above, you have no control over the foam once it's out of the can. We put more foam in one of the passages than it could hold. The result was a couple of very ugly bumps in the outer trunk lid. Which cost a lot to replace..

I would think that a blob of seam sealer in the right spot would keep the vibrations to a minimum or maybe panel adhesive( autobody panel not man cave panel)

[crussell85]

Originally Posted by slodat

I did a very elaborate car audio installation in a 2003 Mustang. The trunk lid is made of ABS plastic or something similar. The inner support structure is bonded to the outer lid piece. The subwoofers were causing a lot of rattles in the trunk lid. We filled the voids with the spray foam as you mention. It **looked** like it was working out well. As Dan says above, you have no control over the foam once it's out of the can. We put more foam in one of the passages than it could hold. The result was a couple of very ugly bumps in the outer trunk lid. Which cost a lot to replace..

what foam was used, was it the gaps and cracks or was it the window and door. The window and door is made to be minimal expansion so you are not pushing and stressing windows and door. I would think you used the gaps and cracks which is made to really expand.

[DanTwoLakes]

crussell is right, there are two types of Great Stuff, one expands like crazy, and the other is limited and expands very little. Neither one belongs in a car.

Think about this.....Great Stuff has been around for at least 20 years. If this was a viable option in a car, wouldn't everyone be using it? Wouldn't the car manufacturers be using it? They're not, are they? I'll bet you can't find one mention of it anywhere on the internet or anywhere else being used successfully in a car. You need to look at mainstream solutions, and expanding foam is not one of them.

[slodat]

It was the customer's request. I've never used it again!

[DanTwoLakes]

Slodat, I wasn't trying to scold you, I was trying to talk to the original poster. I figured somebody asked you to do it that way. I have customers who ask me to do some really stupid things.

[matt167]

I think great stuff spray insulation is a better option for reconstructing body panels, even then, a backyard fix that just wont last

[ogre]

Originally Posted by DanTwoLakes

... the insulation will loosen up and squeal like a baby pig as it rubs against the metal shell of the car. ...

i have to with dtl's amusing view here. i have used this in construction, it does crumble into powder under stress and movement.
i did use rhino liner spray-on bed liner under my cab, back of inside cab, innner fenders and fenders as deadener/chip proofing. it gets pricey if you do a lot. the rattle can stuff is worthless.

[sparkydog]

There IS some kind of automotive grade expandable foam out there because it is inside my GM Z71 cab. For instance it is used to fill in the wall cavities of an Xcab down at the floor level. It is pliable not rigid like great stuff.

GM also uses expandable foam between the roof sheet metal and the support ribs that hold it in shape.