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Senior Member
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4,358 Posts
Discussion Starter · #1 ·
Foam filling the chassis

This was discussed abit in another thread. I want to share the info I've found out about it. Also put up some link to the stuff.

Now in the below article originally posted by ma71supraturbo, they increased the Z's chassis rigidity by 40% using the 2lb mix. Shawn dude (in the old thread) said that filling the tunnel between the rear strut towers was an amazing difference. I believe he was using the 2lb mix also. Now check out the following link, http://www.shopmaninc.com/foam.html . Compare the physical properties of the 2lb foam to say, the 8lb foam or even the 16lb pound foam. The 16lb foam is 1500% stronger than the 2lb mix. You are ramping up from a 50psi flexural strength to a 750psi flexural strength. Can you imagine the chassis filled with that?

Some important notes that have been left out of the other thread and in the below article. DO NOT try and contain this stuff. You need to have relief holes every couple inches for this stuff. Just tape off the surrounding area so it is easy to clean up. It turn out the boat folks deal with this stuff all the time. I've been lurking their forums finding out about this stuff. What happens when you don't have relief holes? The foam WILL bend/bust/break whatever you are pouring it in. The best story I read applies directly to us. On of the boat guys pour this stuff into his car's chassis to strengthen it. He did not have relief holes. The chassis was twisted and busted beyond repair!

Fortunately pretty much all the places we can pour this in to strengthen our chassis have holes already, so we're relatively safe. However if you were thinking of welding those holes over, think again.

Here are some links to buying foam that I have found.

3M's application

http://www.shopmaninc.com/foam.html

http://www.betterfoam.com/one/1ComponentStraw1.html


Heres the article.
 

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Broke Supra Addicted Fool
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801 Posts
Sounds like just what our overweight wet noodles need ;) Whats the price per can of this stuff? I would definately like to experiment with this!
 

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Senior Member
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Discussion Starter · #5 ·
Even using the highest density foams and you filled all the empty frame areas in the car, I doubt it would add more than 20 pounds to the cars weight.

Prices are in the links.
 

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deadbeat extraordinaire
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419 Posts
i see your point, but if done properly the cavity should be filled entirely thus preventing any water from entering. the problem would be filling the cavity completely and maybe causing the water to accumulate elsewhere.
 

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Discussion Starter · #12 ·
Good weather seals around the windows and hatch should take care of this one relatively easily.

Most of the drain plugs aren't anywhere near the chassis cavities that you would want to fill with this stuff. All the drain holes are on the floor panes. Actualy, I need to do something about that. Having a stripped car only holds it's appeal just so long. Gotta put some carpet down or sumthing.
 

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Premium Member
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6,754 Posts
oh man, i thought you were going to foam fill it to make it float like on MONSTER GARAGE aight peace :chicken: and tell us how it goes
 

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a point that a friend of mine brought up was this.

won't the foam manipulate the crumple/crash zones of the chasis?

any ideas on it fellas? my friend drives a volvo so there isn't really any use for him to strengthen his chasis. he's happy with it's stiffness. but he did question the safety issue.

Sdude, you got some input?
 

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Discussion Starter · #16 ·
Heh, I think the MK3 has designed before the advent of crumple designs. It's built to punch through other cars, as many a MK3 driver in an accident can attest to. Even if not, those should all be up in the engine compartment.

Pretty much all of the places I have found for foam filling is inside of the passenger cabin. Once in there you don't want any crumple zones. Hence the various racing organizations requiring roll bars/cages if you're any fast.
 
G

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I just thought it pretty funny that anyone is worried about crumple zones on this forum. Yes, I think it would change the body's crumple zones dramatically were you to consider the hatch a crumple zone. Mostly, I thought you'd be looking to strengthen the cabin itself. Would anything ahead of the firewall hold foam?
 

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what benefits would you be looking for with a foam filled driveshaft? it doesn't do any flexing except for torsional, and even then it is miniscule. i doubt the foam would add a measureable degree of stiffness to the driveshaft. the goal on the driveshaft is to limit the amount of rotational weight, not add to it. these are just my thoughts on it and why i think it won't work.
 
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