so i read this topic a while back on SR20forum about this guy who was doing a restoration of his "classic '93 SE-R" and i was immediately intrigued. here is a
link to the topic on SR20forum. it's a lot of reading so ill sum it up.
what he's decided to do while restoring his SE-R was load up the car with as much chassis bracing and suspension mods that were commonly availible for those cars. fender braces, bushings, strut tower bars, he welded in a thick sheet of metal behind the rear seat to stiffen up the area between the pass compartment and trunk, etc. he may have missed a few, but thats besides the point. and on top of all the chasis bracing and suspension work he, had heard about something that hasn't been too commonly practiced in the typical modding of a car, which was foam filling the chassis wherever possible with this commercial grade urethane foam. from what i've read, its becoming more and more popular with new car companies to fill certain pieces of the chassis or subframes with the stuff, increasing rigidity, and overall handling. i personally had never heard of it, so i kept reading on. what i picked up from reading this entire thread was that there are many different density foams availible, and the higher the density, the better. what this guy did was put a very high commercial grade density foam in the floor bracing and some of the mid sections of the A, B, and C pillars, and in the upper pillars and the rest of the body he put a slightly lower density foam (out of ease, because the lower density foam came in like an aerosol can, while the high density stuff needed to be mixed gallons at a time). the lower density foam he used was called "handi-foam", which was a 2lb density foam he found was supposed to increase chassis rigidity by up to 40%. thats a damn good improvement by itself, let alone in combination with the 8lb density foam he used in most of the car, filling the whole floor structure, lower abc pillars, and a good portion of the front frame, which is just ridiculous. lol. it wound up working very VERY well for this guy in his restoration. and being VERY effective. essentially what stiffening the chassis to this extreme does, is FORCE the suspension to do it's job, nearly eliminating deflection to the unibody/frame. the guy went picture crazy, and basically documented the entire process (pages 5 and 6 in the link i posted) he wound up going completely all out by using "quietcar" sound deadening paint all over the interior as well, to decrease NVH. the stuff is much like the sound deadening mats we have all seen before, only availible in liquid form, it's supposed to be lighter and work BETTER, but thats besides the whole point of this post. in the end the guy basically praises the whole process as a total success, and reccomends it to anyone willing to try.
overall i was extremely impressed with the entire build and thought i would share. the guy has basically made a "how to" for this, all the info is there, what he used, how much of it he used, an estimation of how much weight it would add to the car (wound up evening out with the weight reduction he did), he did lots of experimentation with different foams at different temps, etc, etc. the only draw back this guy could have had (didnt, due to careful planning and paying EXTREMELY close attention) would be the possibility of bulging in some sections, due to over filling, but he experienced none. that and some were unsure of the durability of the stuff, as in, how long will it retain it's stregnth for, as it's not totally a solid, but aerated. overdoing the density might help with that (as he did in this situation) but will increase chances of bulging. the stuff is used in vehicles like busses, larger RV's and things like that, so i think it'll hold up to the abuse of a little 4 cyl economy car.
The reason i put this in the Suspension and Brake Forum and not the Other Cars forum, would be to bring this to light, and ask, has anyone ever even heard of this? let alone tried it in a J? since i read about this i've been oh so interested in it, but doubt i will ever try it at the level this guy has taken it to, and hope that maybe posting about this would either bring foreward someone who has done it, or interest someone in being the first in our community. i hope someone else finds it as interesting as i did, and has the patience to read through an 8 page post on another forum.
i really truely am sorry if this has been covered befoe, but i for one had NEVER heard of this, searching yeilded no results for me on our site (famous last words), and i for one, found it quite the interesting read, and thought it might be a good discussion to bring up here. so i guess have at it, what do you guys think?
I was considering doing this to a CF trunk to allow for a bit of added strength to it, as well as keep the overall weight still down a bit. wasn't going to go to the extreme, maybe at most do it to the a, b and c pillar, but that's about it. . . .
That was a really cool read, thanks for posting that up! I have never heard of that before.
Now someone try it in a J!
car companies have been doing it for years.. There are 2 major types of foams out there tho.. structural and sound deadening.. one is not the other.
huh, pretty cool, not sur eid waste my time though, that less time figuring out how hard you can push the car on the track wihtout foam, and enjoying the time spent doing so.
Quote:
I would *guess* that 50 pounds (or less) worth of foam is less weight than a proper cage, while providing nearly the same (?) structural rigidity
Well, at least he used the question mark... I'm sure the diagonal bracing provided by a proper cage would still put the foam to shame. For a daily though, this isn't bad. Another benefit of the cage is that this stuff won't pass tech when a cage is required
fortune cookie say: better a delay than a disaster
ive heard of a few people doing it and seen some articles on it and on tv at one point, its supposed to really stiffen things up nicely. i had thought of doing it to my car back when i started but i never got around to it. the only real issues is making sure you use the right type of foam. and that you new how to figure out the proper mixture properly so you didnt blow out any welds and screw the car up.
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Stephen (manta z) wrote: There are 2 major types of foams out there tho.. structural and sound deadening.. one is not the other.
i did forget to mention that. in the thread i posted, he does go into this a little as well. he talked with someone who had filled a good portion of the chassis and interior with the sound deadening foam with the sole intent of reducing NVH drastically. that was also another interesting read. but you are absolutely right, one is most certainly not the other. the high density stuff is hard as a rock, while the sound deadening stuff is very soft, almost like rubber, and does nothing for rigidity.
OHV notec wrote:Quote:
I would *guess* that 50 pounds (or less) worth of foam is less weight than a proper cage, while providing nearly the same (?) structural rigidity
Well, at least he used the question mark... I'm sure the diagonal bracing provided by a proper cage would still put the foam to shame. For a daily though, this isn't bad. Another benefit of the cage is that this stuff won't pass tech when a cage is required
yea i'd have to agree with that. a cage would definately put this whole process to shame. metal is still stronger than foam, lol. but it is definately a good choice for someone who wants to stiffen up the chassis just enough for a daily driven car. in this guy's case he didn't want to lose functionality of the interior at all, like one would with a cage. he had great luck with it in a daily driven car.
Why the hell not ,next time I have the car apart Ill give it a try.
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In Loving Memory of Phil Martin December 14 2005
Alexis: Dustin, you're ghey, lol. I am better. I have tits, and tits rule all.
Alot of people want the rigidity but not the cage so they foam it along with stitch weld the seams to create a chassis almost as rigid as a caged vehicle.
I'd seen this in SportCompactCar when it was still published and had excellent stiffening of the chassis with the cars they were working with.
And it's also good to see some people accepting that the chassis is an area much neglected by most that tinker with their rides.
Everybody wants more power but the car as a whole is then neglected for this one thing called power.
Nice article and read.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO! 
when chassis stiffing is brought up youre the first one who comes to my mind, so i was hoping you'd chime in on this one blu. the only thing i'm unsure about would be the durability of this stuff. as in how long would it actually last and hold that rigidity on a daily driven, or even track whored car. i'm sure the very high density stuff would hold up for quite some time, but as for the lower density stuff i'd be interested in seeing how/if it would deteriorate over time and continual usage.
although its not widely practiced, i would love to see someone go to this extreme on a j-body. i think it would yield fantastic results.
if only i had the balls and deep pockets. maybe some day.
Take into consideration that if you've ever used the stuff, it's pretty durable.
Yeah it cracks and dries out over time but in something like this application, it's sure to last longer than you'll ever own the car.
My only other fear of it being in the daily driven car would be how well it would stick to it's surroundings. With any flex of a car there's a chance that separation of the foam to its walls could deem it useless.
I've actually thought about doing this myself when I read about it in SCC magazine. That and stitch welding everything would make for a car that is very stiff for racing but still has all the accouterments of a daily driven car.
Somehow the plans have changed and other avenues of a build lay on the horizon.
Anyway, good luck with it and let us know if you decide to go through with this. A good write up is in the works too if you do this.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
damn, i must say i am impressed. i have never heard of this before and am definitely intrigued. will be getting some more information on the subject.
there are a few cavities under our cars that could be filled for sure...
james? wtf broph? id have figured you would have been drooling over this LOL
you know you wanna do it...
Trailer Queen corvette wanna-be with 40 coats of wax and powdercoating that soaks in.
Not really Brad.
I'm pretty happy with the way the 'blu is sitting right now the way it is.
With the exception of the fender braces I'm wanting, there's not much left to do if you know what I mean.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
after i read the thread i went looking for more info on the foam and here is what i found
the very high density foam:
USComposites 8lb density urethane foam
the Handi-foam that was used:
Handi-foam
on the handi-foam site, i am unsure what the different packages are, or why they are differently priced, but i can only assume that they are just larger quantities of the product. but i dont know for sure. this is the only site i have found in my searches that sells the stuff online.
just in case anyone was interested
Quote:
Attacked with a garden hoe.
http://i499.photobucket.com/albums/rr354/ShawnB1/Foaming%20Front%20Rails/BadgerRestorationFrontFendersMis-6.jpg
Yes folks, that is the actual asphalt itself. Permanently attached.
See how thick this is? I cannot break it by hand. Not even close. You could knock someone out with it.
This part made me laugh. It's interesting though, I'd really like to see some experimental data as to the stiffening effect to a vehicles chassis with some numbers attached. I bet it would be messy as hell!
" To study and not think is a waste. To think and not study is dangerous. "
You may be able to find the original SCC article and I believe the guys at Modified Magazine have done this too.
Some research on this would be revealing for sure.
Good luck with it.
Like everyone here, I'm intrigued with this myself but right now, don't have a car that I'd be willing to do this with.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
Modified article
they did this to a very well built 300ZX some time ago. very cool.
Quote:
Foam-Filling the Chassis
In any high-performance car, it is impossible to make the chassis too stiff. The stiffer the chassis, the higher its natural frequency, making the energy imparted to it by bumps less likely to excite the body's structure. A stiffer chassis enables the use of stiffer springs and shocks without hurting the ride. This is because a stiff, non-flexing chassis transfers more force into the suspension where it can be dissipated by the springs and shocks instead of transferring the force to the occupants. A stiff chassis is also more responsive to roll rate tuning for balancing understeer and oversteer. This is one of the reasons why automotive engineers are continually investigating ways to stiffen chassis without adding weight.
In a final bit of reengineering to stiffen the body, we injected the chassis with catalyzed rigid structural polyurethane foam. Structural foam, in the 2 lb per cubic foot density that we used, can stiffen chassis members up to 40 percent.
Higher densities of foam can increase stiffness by up to 300 percent. Since we cannot retool custom parts to redo the Z's body, we figured that this would be an excellent, low-cost way of greatly increasing chassis stiffness. Injecting foam is not a new technique for chassis stiffening. The Infiniti Q45 uses this sort of foam in some of its chassis members to increase stiffness, as do a few other premium cars. In fact, the foam we chose is the foam recommended to repair damaged Q45s.
To get the correct foam for our project, we contacted Art Goldman, Foamseal's automotive product manager and author of an SAE (Society of Automotive Engineers) paper on the use of structural foam for the stiffening of automotive unibody structures. We used Foamseal's two-component foam kit, p/n 11-22 to fill the main members of the chassis. Like we mentioned earlier, Foamseal is the supplier that I-CAR, a national certification group for quality auto repair, recommends for the repair of damaged, foam-filled chassis. The Foamseal kit uses a two-part catalyzed polyurethane foam, which quickly cures into rigid, waterproof, closed-cell foam. To prep the car, we carefully masked off all painted areas anywhere where the foam could drip. As this sort of foam is a thermosetting catalyzed plastic, we realized it could be icky if it spilled on paint or any part of the car's interior. This foam is nasty stuff. It is impervious to all known solvents and cleaners.
Rubber gloves must be worn. Get some of it on your hands and it will stay there for more than 3 weeks--don't ask how we know. Do not get this stuff on your paint. Wear old clothes; we ruined ours while learning how to handle the product. We injected the foam into the rocker panels and frame rails of Project Z through existing bolt and drain holes. When injected, the foam reacts like shaving cream and quickly expands to fill the empty space. You can judge how much foam to add by watching its expansion progress through some of the holes. Once injected, the foam expands and begins to cure in about a minute so you need to work fast and plan how you inject the foam before you start.
The life of the foam kit is limited to a few hours once the seal is broken. We filled all of the Z's unibody frame members using five foam kits. When foaming a chassis, you must remember the wires and other lines that pass through the chassis must be relocated or they will be entombed forever.
We were amazed at how this simple procedure improved the performance of the car. The chassis now almost feels like it has a roll cage. A sloped driveway can be driven up sideways with nary a creak. Even though the Z already has a pretty tight chassis, it feels more solid. The ride has improved and road noise has been reduced noticeably. We bet that the car will be even more responsive to chassis tuning measures in the future. If you are a slalom racer, a road racer, have a lowered car or even just want a smoother ride; foaming is a worthy, easy-to-do modification. Foamseal has foams in densities as high as 10 lbs per square foot if you desire to make things even stiffer.
Do not--I repeat--do not attempt to use cheap, hardware-store canned foam. This is not the same thing, and if injected into your chassis, will form a gummy mass that won't dry. Foamseal foam is a professional grade foam, which although it is a little unforgiving to cleanup mistakes, has superior mechanical properties and catalytic curing so it will dry even in an enclosed space.
Taken from the article from Modified Magazine.
And thanks Jon for the link.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
lots and lots of prep work indeed. from what i've seen it helps to have the car completely gutted to do this.
i believe gorilla tape is reccomended as it doesn't stick to the foam when its dry. rubber is one of the only things this stuff wont stick to.
if i had the time/money i would be all over this, but if i started tearing the interior out it would turn into much much more than just the winter engine project it is now. lol. and i dont have that kinda cash flow rite now. so i can only hope for someday being able to do it, if the car doesn't rot away first.
actually something else that intregues me quite a bit is the "IKEA" brace. (no idea what it stands for, if anything) it's the 1/4" or 1/8" (no idea how thick) sheet of steel welded in behind the rear seat to close up the hole between the trunk and the pass compartment.
i like how it solidifies the seat back section, it's relatively easy to have installed, and if wanted, you could still retain the factory rear seats. dunno how much it weighs, but it can't be light. especially if it is 1/4". i would imagine this would only help us out too, but i have no real basis for comparisson.
i'm glad you guys are taking to this stuff. gotta be honest i didn't know what to expect when posting it.
A piece of 20-22 Ga. sheet steel would do the trick for stiffening the rear chassis. You are only trying to control lateral body shift with a brace like that, not preventing bullets penetrating. The OEM Rear Triangulated Brace would do the same thing. This would still allow for some use of the pass-through. There is also someone (sorry, whoever that is I forget who you are!) who did a rear X-brace, that does the same thing.
I wouldn't do it though, I use my pass through too much.
Edit: The next thread I Looked at down this Forum's page! 
Edited 1 time(s). Last edited Saturday, January 16, 2010 10:57 PM
MadJack wrote:There is also someone (sorry, whoever that is I forget who you are!) who did a rear X-brace, that does the same thing.
I wouldn't do it though, I use my pass through too much.
Edit: The next thread I Looked at down this Forum's page!
I have some decent pics posted in that thread of Blu's, Mark's and My setups
I still have some pass through. I needed to haul a front bumper and it fit
I am quite interested in this foam.......I think I got a spring time project lined up already...
i've always wanted to try the X bar in the trunk. i kinda figured the ikea brace would be the same kinda thing, only a completely solid way of doing it. i dont use the pass through a lot, but enough to warrant not needing it completely sealed off, so i kinda just figured id throw it out there.
i'd still love to see someone go through with the foam. the more i think about it the more i wanna do it. if even just the 2lb density handi-foam around the floor cavities.
The foam is a great idea for track or comp. cars but be carefull were you use the stuff on unibodys.
The foam is flamiable and is a one time shot once its done thats it no re-dos.
So fill the frame and stay away from the shell if you plan on useing it for a daily only, this stuff makes body repair
hard as h@ll and can block factory pockets made to bleed off water and allow air through.
http//www.umods.org/drift.html
umods@live.com/ddiaz@umods.org
