Unibody Welding

[cardot33]

where are you reading the 1.75 lb/cu ft structural part? i can't find it anywhere. i figured out its flame characteristics though, interesting stuff.

[jman093]

Here's a data sheet:

http://www.foamkitsolutions.com/data/pdf/A16129_Handi-Foam_II-12_II-22.pdf

[danbettis]

IMHO SCC and 90% of the other magazines are clueless when if come to truly making a car faster. Modification does not mean faster. I am interested in using this stuff on one of our road race cars if it will help, otherwise I'd forgotten about it already. Seeing in the the adhesives section and the expansion rate was were I was coming from on it being structural or not. I asked a friend of mine who does this stuff for a living for OEMs. He does a lot of FEA modeling and real world testing, so I trust what he says. It is a structural foam, but it is borderline by today's standards. This stuff is easier to use than the ones I mentioned above, but its not near as strong. He also added if trying this stuff, to from something to practice on before you ruin your car. Also regardless of what they say the cleaner you can get the metal the better, but he offers no advise on cleaning the metal inside rails and pillars. But I got him thinking and he is going to ask around, since he only deals with new bare metal. But he really pushing the idea, basically saying you can lose have the strength in the bond or lack of a bond.

[woody90gtz]

A friend is teling me the cars with structual foam in them are usally precast. There are a few that are injected. More imporantly he says you have to get the metal extreamly clean or its a waste. The bond it makes with the metal is where it gets is strength and keeps it fomr making noise it self. Even the precast blocks are glued in. Also there is a big differance between structural and the acoustical foams. Mainly thier expansion rates. The acoustical expands alot more and can break welds and rip sheet metal, but is not very strong compared to the structural stuff which will expand much less.

Dow BETAFOAM and 1908 Fusor Terocore Structural Foam are what OEMs are using and suggest in repairs.

Finally, someone who has worked with it and offers advice! Thank you!

I think it would prove very difficult to get the metal in the unibody rails, etc clean. I guess a pressure washer in the drain holes would be the best bet... I hadn't even thought about that as an issue. I assumed the foam would custom-mold itself to the metal and stay secure that way.

I'm very interested to see what he has to report back after asking around.

[danbettis]

To clean the rails need to use some sort of cleaner that does not leave any residue. The stuff made for repairs is more friendly to this situation supposedly, but nothing is going to be better than clean bare metal. In the end if you want it stiffer spot welding the hell out of seams will probably be best and do cheaper, be lighter, and with any real drawbacks. Also got into some talk about foam in the wrong places is useless if not harmful. Rails running down the car good, but vertical rails not so much unless you can complete the loop. In the end performance wise probably never notice the foam, especially with street tires since you never really have the grip needed to really get things twisting. But it may help with noise or if your in a wreck which is where it makes the most difference (adsorbing energy) assuming it does not make it worse. Also should keep in mind torsionally tubular structures are almost always stronger that solid ones.

I had been thinking also of using it in a chassis I am designing to fill in between alum panels that encase some of the tubing. Like the the floor and cockpit. But it started getting heavy and I went back to bonding alum honeycomb panels if I go that route. Ends up much lighter and stronger.