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Discussion Starter · #1 ·
I remember you posting something about shooting expanding foam into the door sills to help stiffen up the body. Could you explain how to do this and how much it will help? I'm really starting to get annoyed by the amount of body flex my car has. Thanks.
 

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basically they just shoot the foam into every empty chamber of your car.(w/o affecting your windows, of course) In between the panels of the doors, the fender, and places like that. By introducing these material into these empty chambers, things do not get as much space to rattle around and will be supported by the foam, thus enhancing the rigidity of the body and reducing body flex.(and even road noise) Some extremers even put aluminum nails almost everywhere as a way to save weight and stiffen the body.(once saw a R34 saved awfully a lot of weight by doing this on Japanes REV magazine) Not many ppl in the US cares about these stuff, that's why you don't hear about them as much. In Japan and other Northern Asian countries, improving body rigidity is one of the first things they'll do before other upgrades.
 

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Filling the door sills with foam is an old racers trick. To understand it, get an old paper towel roll tube and try to bend it, bends pretty easy right? Now go to Home Depot and get the expanding foam sealant and fill the tube with foam and let it cure. Now try and bend that sucker, bet ya can't do it.

The foam used to reinforce cars is not the same foam as the foam sealant so don't even think of trying it yourself with that.

It is useless to faom doors and fenders as they are not part of the basic structure. Foaming the sills/rocker panels can help a good bit but you have to consider any current or future wiring that runs through there.

I think SCC did something about this mod. I'll try and look it up later.

PS: Did you know our floorpans (at least the G2) are already a honeycomg sandwich. Pretty stiff stuff.
 

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Expanding Foam

I was just thinking about this the other day. I have the Evolution Body Kit, that happens to have the pretty large front lip on the bumper. Okay, well my wife (bless her heart) cracked the front lip a while ago and I am looking at fixing it pretty soon. I don't know all the tricks of being an auto body pro, but I was wondering if there was some "expanding foam" that could be added to the inside of the front & rear bumpers, as well as the side skirts for durability and less flex. Is this what I'm looking for or is there some kind of special insulation for this?

Thanks fellas,

Gil.
 

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Discussion Starter · #5 ·
Thanks for the input guys, you've given me a lot to think about. Dave, you said that the foam used to reinforce cars is different than the foam sealant, does that mean that the foam sealant that I can buy won't work?
 

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Like I said, I have to dig up the article. But pay attention to my wiring comment. You don't want to be sealing your wiring up so you can't pull it if it shorts in the future.
 

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Discussion Starter · #7 ·
I will have to think about that but I don't know how much wiring is running through there. If it's just a few wires you could run a conduit of some sort through there for the wires to go inside of, then foam around that. That's what we do for house wiring.
 

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Dave C ver2.0 said:
Filling the door sills with foam is an old racers trick. To understand it, get an old paper towel roll tube and try to bend it, bends pretty easy right? Now go to Home Depot and get the expanding foam sealant and fill the tube with foam and let it cure. Now try and bend that sucker, bet ya can't do it.

It is useless to faom doors and fenders as they are not part of the basic structure. Foaming the sills/rocker panels can help a good bit but you have to consider any current or future wiring that runs through there.

PS: Did you know our floorpans (at least the G2) are already a honeycomg sandwich. Pretty stiff stuff.
1. Yeah, but never seen them talking about those on us magazines articles and speed vision etc. Even when they are talking about big figure HP cars. As I said, it was a comparison between how many ppl cares about those in the states and back in asia

2. in fender = similar effect as fender struts, just like the paper towel trick that you mentioned. It minimizes nose-body flex especially on FF cars
in door panels = you are right, not effective, don't know why they do it. Probably to increase safety???:p
sills/rocker panel?? sorry I'm FOB, can you explain?? :)

3. tasty??:D
 

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Discussion Starter · #9 ·
How would you put foam in your fender? Don't you have to have a sealed section for the foam to expand into? Maybe I'm missing something here but I don't think there are any hollow sections in our fender. Please let me know if there are.
 

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sandwiched inbetween the inner(piece that you see from the engine bay) and outter fender panel(wat you see from outside of the car). No, I don't know how they did it. I'll try to get the magazine from my friend and see if they talked about it in details.
 

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Meanfly, I hear ya on the Evolution kit. I've already had my front cracked, and when I had it repaired at the body shop they added more layers of fiberglass to it to make it a little more sturdy.
 

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SammyD

This will be the second time I have repaired the Kit! I did do the extra layers of Fiberglass, but I'm looking for more volume behind it (ie expanding foam!). Again, I don't much about it, but I was hoping that someone here could enlighten me on a brand or material in addition to extra fiberglass sheets.

Sorry to hear about the front Sam

Gil.
 

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actually just read an Evo VII article, and Mitsubishi did put expanding foam into the door panels at the factory. They claimed that it would increase the stiffness of the body. Guess there are things that we, the general public, overlooked when making conclusions. Also, another way to stiffen the chasis is to increse solder points.
 
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