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Old 01-13-2007, 09:48 AM   #1
jcsaleen
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Structural Rigidity enhancement...

I was watching some Japanese tuner videos other an heard about a pretty intresting technique. Since most Japanese sportscars are hollow frame they injected liquid foam urthane into the structure of the car. It enters the body, fills then expands when it hits air and lasty harderens as tight as a rock in the body. Cheap and very effective more so then a roll cage supposedly. I might give it a shot on my FD.

Imput & Other Techniques...
(List only uncommon no strut-bars etc)
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Old 01-13-2007, 11:26 AM   #2
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Re: Structural Rigidity enhancement...

Within limits, that sounds like a good idea. You might want to be careful about rust prevention, any air flow requirement thru the panels, and any degradation of the foam itself over time with moisture, heat, etc.
Might even help quiet the car too.
Good luck!
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Old 01-13-2007, 11:42 AM   #3
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Re: Structural Rigidity enhancement...

and add a few hundred pounds in the process.
not really a good idea i think.
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Old 01-13-2007, 12:11 PM   #4
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Re: Structural Rigidity enhancement...

Actually, the foam is stronger per pound than steel. Its not that heavy.

Let us know how it goes. I would make sure sure sure that the inside of whatever you're injecting is squeaky clean. For that stuff to work it has to have good adhesion to the substrate for strength.
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Old 01-13-2007, 03:30 PM   #5
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by curtis73
Actually, the foam is stronger per pound than steel. Its not that heavy.

Let us know how it goes. I would make sure sure sure that the inside of whatever you're injecting is squeaky clean. For that stuff to work it has to have good adhesion to the substrate for strength.
I definetly will. The whole car will be completely cleaned an cutted before the injection.

Greygoose ~ The amount to cover a whole tubular chassis like mine when compressed is smaller then a paint can. It weighs almost nothing. Watch JDM insider 2 and you will see an R32 GTR completely lined to the hilt with urthane. The amount when compressed was about as big as a can of paint thinner.
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Old 01-13-2007, 03:46 PM   #6
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Re: Structural Rigidity enhancement...

i must be misunderstanding the process.
what are you filling with foam.
the hollow parts of the frame, or the hollow parts of the body (like inside the doors)
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Old 01-13-2007, 03:50 PM   #7
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by GreyGoose006
i must be misunderstanding the process.
what are you filling with foam.
the hollow parts of the frame, or the hollow parts of the body (like inside the doors)
Only the hollow parts of the frame... "Structural Rigidity" Not "Exterior Rigidity"
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Old 01-13-2007, 03:52 PM   #8
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Re: Structural Rigidity enhancement...

ooh, i see. somehow i read your original post to mean that you were injecting this stuff into the body, which would have added a lot of weight.
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Old 01-13-2007, 03:58 PM   #9
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Re: Structural Rigidity enhancement...

Come to think of it, It could replace sound defining material as well. The material is lighter then metal an just as strong due to it's structure. Imagine hundreds of thousands of tiny archs to form one massive or in this case regual size structure. The foam isn't solid nor dense so it's very light, hence why I'm doing it over a roll cage.

IMO ~ It's impossible to inject it into doors with moving parts sych as power windows or even manual windows.
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Old 01-13-2007, 04:46 PM   #10
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Re: Structural Rigidity enhancement...

I remain sceptical.

While it'll be great for sound proofing and may possibly stronger than steel (weight for weight).

How is adding less than 1lb of foam to your car going to give a structural benefit?
There is no way that can ever compete with a rollcage for strength and safety.

The stiffness of foam is terrible. It will not be in any way comparable to adding extra metal to your car.
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Old 01-13-2007, 05:25 PM   #11
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Re: Structural Rigidity enhancement...

Quote:
Originally Posted by KiwiBacon
There is no way that can ever compete with a rollcage for strength and safety.
Strength yes, Saftey No.

Sometimes hollow is better and it's a foam that harderns into a solid plastic not a foam that turns into sponge or cushion. Do you know that your bone structure is almost the same structural patterns as this foam? Many things through the years have been many or hollow peiced an the fact is they're stonger. Perfect example is carbon fibre... Why is it so durable and strong because it's a fiber an not a solid monopiece structure.

Honestly I don't care about safety because a cage in an FD really won't do that much as far as safety at the speeds I access in the FD are no where near safe even for a cage.
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Old 01-13-2007, 05:28 PM   #12
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Re: Structural Rigidity enhancement...

Cell structure of urthane ~


Cell Structure of Human Bone ~

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Old 01-13-2007, 06:15 PM   #13
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Re: Structural Rigidity enhancement...

you do know that it doesn't take much lbs of torque to break bone right?

I don't think it's worth it.
if you increse the rigidity of the base frame, aren't you going to have to work on the suspension so you don't wreck your ride quality? And if it doesn't add that much rigidity to neccessitate re-tuning the ride, then is it worth it?

Incidentally, the strength of carbon fibre is because of the criss-cross layering of the superlight (material) fibres, not because it is "hollow", which it defintely is not.

And what speeds are you doing in that car which would render even a full safety cage useless?
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Old 01-13-2007, 06:17 PM   #14
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Re: Structural Rigidity enhancement...

I'm not going for ride quality (I'm installing full Race spec Re amemiya Quantum Flex Coilovers as well as a stronger an even more rigid strutbar (s) as well as lower bars an a custom X brace)

My last trap speed was 147mph before my boost cut-off kicked in. No it wasn't Qt time

Fyi - I was explaining how one solid structure is sometimes not as strong as servral not the hollow part. (Atleast thats what I mean't to say with the whole whole carbon explaination)
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Old 01-13-2007, 06:33 PM   #15
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Re: Structural Rigidity enhancement...

the other problem I can see from injecting expanding foam into a hollow tube frame is that while it adds rigidity, it also puts extra stresses on the joins and this is something you can't physically see or even measure without very expensive equipment. This in turn can actually weaken the structural integrity of the frame; not something you'd really want to do if you are intent on modding the car into a (pointlessly) overstiff straight line racer.
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