http://www.itwfoamseal.com/auto_aftermarket.htm

Foamseal essentially it's a foam used to fill cavaties in the major structural areas of your car. It is a foam specifically develeped for cars and has been proven to provide an increase up to 200% (40% is more common) in structural rigidity. Blah, blah blah. Basically it's seam welding at a fraction of the cost. If you keep track of Sport Compact Car's 300ZX project they swear by it. My question is has anyone used the stuff on their 7 and if so where?

 

Technically they are call Polyurethane Expansion Foam. This technology has been used in aviation industry to fill up the cavity on the airplan wing. People in Japan use it a lot. The disadvantage is if you get an accident, it makes it very hard to fix the area where it is filled with foam. I also believe that it will make the frame too stiff for daily use as it elimnates all the flex on the chassis. There is a local shop that makes those foam and I am thinking of doing that on my AE86.

BC

 

Eliminating chassis flex is always a good thing and every automaker in the world is striving to make their chassis as rigid as possible. The idea is for only the suspension to respond to any wheel movement. All forces should be absorbed by the spring and damper; never the chassis. This allows easier tuning for both handling and comfort of the passengers

As for the foam your point about repair is the biggie. Foam will certainly add stiffness but filling any cavity that has wires, cables, fluid lines etc is begging for trouble. You can't get the foam out once it's in there so everything else in there is now permanently sealed into the unibody.

 

Cant you pour some gas on it and it begins to melt? Or some other product like mineral spirits or something.

 

You just proved my point. So you need to make a repair and you just dump some **** in there to eat the foam and turn it into some sort of gooey mess (and perhaps all the wiring, cables or hoses in there too). Now you have a unibody that rather than being full of foam is full of big gooey mess. Now what are you going to do?

 

Polyurethane foam becomes a very hard rubber with about Shore 95A hardness or higher (depends on what type of polyurethane you want). When the liquid A compound mixed with B compound, they under go chemical reaction and begins to expand to a larger volume and fill up all the cavities and becomes hard rubber . If you think it can be melted, you are talking about burning rubbers which I think it will be like burning you tires or any like of rubber or plastics that create black smoke and air pollution.

BC

 

DamonB, i dont think all car makers are making their cars as rigid as possible.... that would be horrible for crash tests.

im sure there are certain chemicals that can melt/disolve it without making smoke...

 

Take a foam cup and pour gas or mineral spirits on it, and watch what happens. No smoke, the gas eats away at the foam. Or if you want to try it will REALLY strong sutff use some parts cleaner. That stuff will cut through anything.

 

Crash energy absorption is different; you can be rigid and still absorb energy. All car makers want their chassis as rigid as possible. Chassis rigidity is measured in hertz (passenger cars) or torsion (racecars). Check out how often the resonance frequency of a new car's chassis is mentioned in car magazines. The manufacturers are proud of it...

 

As DamonB pointed out, chassis stiffness has little to do with deformity/energy absorption in an impact. Chassis stiffness is measured in torsion and in bending, this is different than impact loading.

 

There are many, many different types of foam just as there are different types of plastic. Your basic coffee cup is EPS foam (expanded polystyrene, or "styrofoam") and will melt easily with many types of solvents. Polystyrene foam is made by dumping small, hard polystyrene pellets into a mold. You then inject in a hot high pressure gas (usually steam) and this causes the pellets to expand. Essentially the pellets are heated and aerated; this makes them expand. You can vary the density of the foam by how many pellets you insert into the mold.

There are many other foams that are resistant to most solvents. For instance the 2 part foams that become active when the parts are mixed that are commonly available as kits for custom molding inserts for racing seats. You put a plastic bag in your seat, sit in it and then dump the agents into the bag. The foam then expands perfectly around your backside and tooshy. You do NOT want that crap to get on you. The heat alone from the reaction is uncomfortable and it will cling to damn near anything and refuse to come off. Similar to the insulating spray foam you can get at the hardware store.

 

Damon is Spot on, on this stuff. It is a hardened foam, and once it has dried WILL NOT go away easily. Gas? won't touch it. The trick with it is apperantly only putting it places were there are no wires, and if there are wires re-routing them so they won't get covered. Frame rails are you maind concern, then you can fill in areas were body panels come together, and so on. Only areas associated with chassis strength matter.

 

We just chopped a camaro in parts (a totaled car we bought on ebay). Anyways I looked in the rear 1/4 panels and they had foam! I'll take a pic of it (if the car hasnt been choopped anymore), my dads using the LT-1 in a 69 Camaro.