Example of polyurethane foam car "sculpting"
 

From: http://englishrussia.com/?p=1949

For anyone considering DIY aero mods, you're going to love the DIY, low-tech method this guy used to goop up and sculpt an entirely new body on a Mercedes coupe using polyurethane foam.

Not apparently for aero, but the low-tech construction techniques should provide inspiration:

http://englishrussia.com/images/latvian_mercedes/6.jpg

http://englishrussia.com/images/latvian_mercedes/8.jpg

http://englishrussia.com/images/latvian_mercedes/9.jpg

http://englishrussia.com/images/latvian_mercedes/13.jpg

http://englishrussia.com/images/latvian_mercedes/41.jpg

Many more pics:
http://englishrussia.com/?p=1949

A good friend of mine acually used this very method back in the early '80s to form big honkin' fender flares on his '67 Mustang. Home depot spray foam, then 'glassed over the top. Turned out VERY strong, but maybe he over did it just a little as it was his first try at it. Placed well in some local car shows as well.

This is acually a plausible method.

Would this stuff be good for blocking out parts of the front grill?

How about making wheel skirts with it?

It would be nice, especially for the wheel skirts, to have something that could easily snap off/on without damaging the skirts.

Probably OK for making a "grille plug", but not so good for wheel skirts, which need to have some structural strength and can only be so thick.

I could however see using this kind of stuff to build & shape the skirt area, apply a release agent and skin it with fiberglass - you end up with light, stiff skirts by making a polyurethane mold to lay the glass on.

Not sure I follow you.

Are you saying make a base using the foam and then fiberglass over it?

Or just making a mold with the foam and filling the mold with fiberglass?

Any ideas on a clip-like thing to attach it to the car?

Have you seen AndrewJ's thread and how he made his skirts?

See http://ecomodder.com/forum/showthrea...amics-312.html

Starting at post #3

That's probably the method I'll end up using once I get moving on my body kit mods. Cheap, easy, and conforms to any shape you can carve :thumbup:

I can see placing a piece of cardboard behind the wheel well and then spraying foam all on top of it till it fills out the space. Then you could simply shave/sand it down even with the body lines. Next pull it out of the wheel well while still attached to the carboard. After that, lay some fiberglass on top of it, trim, sand, paint, and then remove all the foam from the backside and you have a perfectly shaped skirt.

If you put wire mesh inside, would that add enough strength? Maybe some window screen material.

That's not a bad idea. I wonder how he finished the body though. I'm sure he didn't just sand & paint the foam. He had to "skin" it with something - and the same would be true for skirts made this way...

this is the same process im using , its ends up suprisingly strong ... and if you really need strength just carve your shape and fiberglassover it for super strong forms..

This is very easy to do .. Howebver i can tell you a few tips..

1 spray can foam has a tendency to shrink.. in the last part of its curing proces it shrinks up by like 5% so if you filled a gap.. it may unfill when it cures.. this can easly be fixe3d bu doing a second fill of foam after the majority of the foamis finalized.. this second application also fills in any large pockets ofair that form from the spray foram.. Otherthan that , sand it down and smooth it with bondo or fiberglass over it and your got a great light method to sculpt your car.

however this guy may have been going for gas milage, lookat how far he re geared by shanging tire size...
http://englishrussia.com/images/latvian_mercedes/5.jpg

wow..... that is hideous

The people who start a bodykit install and the people who end up with the car one color is about a 1:200 ratio in so cal. See that guy isn't even in America. Fiberglassing: Yet another neat skill I never took the time to aquire in my younger car modding days.

the car or the coat?

:D

That's a lot of squirrels... :p

I tried this method to make a snug fit grill block. I used Home depot spray foam, it didn't cure hard enough to shape. I think this is a good method though. I am going to give it another shot when I get the chance.

both.

im doing that tomorrow on my civic, i will be doing the grill block and filling the fog light areas (i dont have fog lights) but i will be making them removable and held on by double sided tape.

what did you use to try to sculpt, i am going to use a small saw and a grating type planer (an art student recomended that so i will try it)

I used a saw, and a surform. If it makes any difference, and I think it does. I used the spray foam "large areas" It seemed to cure much softer than the other stuff. It does expand much more though. I am thinking that on my next attempt I will fill the large areas with blocks of eps or xps foam, then fill in the gaps with spray foam. I was also thinking about building a lattice with very thin pieces of wood then draping fiberglass over that. Following that I would cover with bondo, and sand it down until parts of the lattice were exposed.

Those fog lamp holes are annoying, have you done any testing with them covered yet? I am doing a couple test runs next week until I can get my permanent covers made, anybody know where to get materials to glass over the foam? Home Depot have it?

you can get bondo brand fiberglass materials from wal-mart, auto parts stores, and home depot., i havent tested yet but i dislike them so much that i really dont care how little of an improvement i see so long as it looks better

Johnpr, Also if you haven't already look under the rear bumper on the drivers side there is a HUGE parachute under there which would be do well to be covered up and became one of my priorities when I saw it.

yep i saw that also, i have been debating on how i want to tackle that area. if i have time i will take measurements and that will help me decide on a material. have you thought about how you will mount a panel near the rear axle, i was thinking about welding some tabs on there. i will take some pics though and figure something out

I've noticed that parachute as well. That is going to be the next project after the grill block. Were you guys thinking of using pour foam to fill it in?

not in the rear, i think with that amount of foam it would be a considerable amount of weight, i am either going to use a plastic or metal sheet, whichever is cheeper for me.

I am going to look into getting a sheet of coroplast for that sheet and test it out, there aren't any high temp parts in the area so anything that can withstand some rock hits would work well.

My kids and I have been building a 3-wheel car from the ground up. We have built the body out of urethane boards purchased from a local lumber yard. Glued the panels together with the spray urethane foam (Home Depot) and then covered both sides of the body with 2 layers of fiberglass and polyester resin. It is quite a job but a lot of fun for sure! Here are some pictures over the years...

http://picasaweb.google.com/stinger3wheel/Stinger

those are some massive wheels

Hokay, so! I bought foam, sculpting tools, paint (black figure two tone black and blue looks ok) and fiberglass making materials! I believe I have everything I need, now comes question one, I am going to make the foam molds for the front of the civic but how much setup time does it take before i can take them out of they're home without the shape changing? I saw that curing time was 8hrs but do I have to leave my car sitting still with foam all over the front for 8hrs or is it like 1-2?

Hello -

Here's a question for a foam bumper mod. Can I apply a thin (clear?) plastic sheet between the bumper and the foam so that the mod is "removeable" after I apply it? The idea is, I want to be able to revert back to stock if I don't like the mod. For instance, on the nose of my car, I would like to preserve the paint job on the bumper if I don't like how it comes out. The bumper would be the "mold" for the foam to rest on.

If yes, then what kind of plastic sheet would you suggest?

CarloSW2

I plan on using painters tap on the paint to protect against the foam sticking to the car, but then what if the foam sticks to the tape you ask? I have not a clue, I'll find out when I try it :-D. you might be able to do it with something along the lines of a trash bag cut and taped where you need it to be. I am not sure if polyurethane foam will eat a plastic trashbag or not, I'm not a ChemE I'm an EE.

I don't recall polyurethane foam melting anything in using it.
I do remember this...it sticks to EVERYTHING!
Gorilla Glue is basically polyurethane.

I would try making the part out of urethane board. They sell it in 1/2" and 1" thick 4'X8' panels. It is covered in aluminum foil so that has to be pealed off.

Once you have your perfect plug. downsize it about 1/8" on the front and sides. Then cover it completely in 1-2 layers of fiberglass and polyester resin.
Of course it wont be perfect but then you can sand it down and build it up where needed with auto filler putty. Eventually it will be what you want and will fit perfectly.

Do you remember what the amount of time before it was removable from the mold was?

I have never used it the way you are planning but the foam takes a few hours to completely cure. It "grows" over time. After 4-5 hours it is good to move on with.

Excellent! Thanks for the help :-) I'll post pics of my sculpture tonight when I start. Waiting till I head to the g/f's place.

You can use blue painters tape to protect the original surface then cover the surface in aluminum foil, which will obviously not stick to the blue tape and therefore release when you are done foaming. Tape the aluminum foil down where it will not stick or conform on its own ...

Alrighty, foam is setting, I used two cans of foam and did the fogs, bottom grill, and top grill, I covered EVERYTHING with painters tape to be able to peel off once it's cured, had some trouble with the foam sliding off the paint but found a fix for that (I hope) I have pics coming a little later tonight of the taped up car and the foamed car, if the molds come out ok I will 'glass them and paint them, if not i'll buy more $5 foam and $10 tape and give it another go!

:thumbup::thumbup: