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Chassis stiffening with foam?

Old 07-23-07, 02:38 AM
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Chassis stiffening with foam?

On my 93 R1, I have everything stripped out. I want to stiffen the chassis a bit, without seam welding because of the labor involved.
Even if I cant get everything, would doing the interior and front be worth it?
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Old 07-23-07, 06:51 AM
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roll cage
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Old 07-23-07, 08:19 AM
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There is a huge thread on this topic on freshalloy.....not sure how much it will help our cars, but I am considering it.

http://forums2.freshalloy.com/showthread.php?t=162693
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Old 07-23-07, 08:49 AM
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If you have it stripped out...are you installing a roll cage?

It pretty much doesn't make sense, if you strip a car...but don't install a roll cage.

Another thing. Is this a street car or race car? And if a race car...what type of racing?
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Old 07-23-07, 02:27 PM
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IMO that foam doesn't seem like it's the kind they use for chassis reinforcement.

It says it's semi-rigid when it cures, but the stuff you want is the lightest kind of polyurethane foam that forms rock-hard with high tensile strength... it's just that, that stuff usually doesn't come in a handy spray device like this stuff does.

IIRC, the RX-8 has foam reinforcement, which is why it's like 50% stiffer than the FD, despite having no B pillar.

FYI, I think marine-use urethane foam comes in like 4 or 5 weights: 4 pounds (per square foot), which is stiff, but soft enough to scratch with your fingernail, 8 pounds, which is very hard (probably the best stuff to use), and 16 pounds, which is basically indestructible (and good luck getting it off of whatever you manage to get it on).

Also, you must make sure the inside of your panels are dry, or otherwise it will hold in the water and it will rust the car from the inside out.

I can't think of any place to put it besides the rocker panels, personally...

BTW, 4 pound foam would be more than twice as stiff as the stuff he used.
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Old 07-23-07, 02:46 PM
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The interior was gutted to do a small rust hole (darn new york car in oregon!) in the floor panel. It also affected the frame rail. It has been repaired.

I only do auto cross and track days, a little road race and small hill climbs with my friend adam once his car is setup. I dont want a cage.

Will it even be noticeable driving it on the street, other then the added stiffness?

The 4 pound is what my brother recommended and I would want to put it in the rockers, rear tunnel hump, and floor braces.
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Old 07-23-07, 03:50 PM
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Infiniti puts it in their cars from the factory.
You will notice fewer rattles in a high mile chassis and maybe a little better feel in bumpy corners because the suspension is allowed to work without having a big spring in the middle(your chassis).
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Old 07-23-07, 06:05 PM
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Didn't look at the link, but assuming you're talking about the foam in a can from Home Depot, don't plan on welding anything to the rocker after you've done it.

I had a customer that came in with an Audi that they had foamed. That crap was hell to work with as everything became an 8" flame shooting at me. If I hadn't been sponsoring him, he'd have had a pretty substantial bill

I would imagine that in about 5 years or so, we'll be sing lots of cars with terminal rocker panels from this "cheap" mod.
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Old 07-23-07, 08:22 PM
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Yep. After the foam is in...it is there forever.
You can't weld the area due to fire danger.
And if you crash, and decide to repair...good luck.
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Old 07-29-07, 03:28 PM
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I used the same product shown in the link (handi-foam II-22) on my FD. My car is still in the shop so I cant say how its tested out on the track, but I can say that just from jacking the car up ive noticed that its much more rigid than before, and if your building a car for autocross (like me) its a huge weight savings compared to a roll cage.
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Old 07-30-07, 11:48 AM
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Just bear in mind that if you are doing this for autox, the foam would probably kick you all the way to Prepared or Mod class. It is not legal in any other category. And if you *were* building for Prepared or Mod, I'd do a real cage.

-Andy M.
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