rossman Posted October 21, 2011 Share Posted October 21, 2011 (edited) Actually, I enjoyed the link you posted. Crash protection and human tolerance to acceleration is actually a very fascinating field of engineering. Edited October 21, 2011 by rossman Quote Link to comment Share on other sites More sharing options...
luseboy Posted October 22, 2011 Author Share Posted October 22, 2011 For some reason I think the original poster was going to go buy a case of "great stuff" foam from Home depot........not the good stuff By the way don't put Armor All on your tire treads either.................. in my defense... no I was most definitely not planning on using the crappy foam. I was planning on using the urethane foam. I researched and thought about it more and realized how dumb it was. no need to be smart about it. Did I say anywhere that I was going to pick some up from home depot? I'm not an idiot, I just get ideas in my head, think about them, ask others about them, research them and then usually decide that they are stupid. oh btw... you spelled texas wrong in your name Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 23, 2011 Share Posted October 23, 2011 (edited) I'm still waiting for the quotation of the FIA section that allows a foam filled structure to replace a roll cage... Foaming an interior component to fill a void and prevent accident acceleration of body parts is well documented since Volvo started putting cardboard tubes in the door finisher panels to prevent broken knees during side impacts with the new federally-mandated door bars in 73... Similarly, composite construction utilizing structural foams is also well documented. But the thought that you can spray stuff inside an existing structure that was not originally designed to have it used in such a matter is again belying sound engineering basis for support. Just because something works well in ONE application does NOT mean you can apply it with similar results everywhere. It simply doesn't work that way. And, to put it bluntly (as John Coffey did...) it screws up more on the car than it will EVER fix. That being said, I 'Great Stuff' foamed the C-Pillar area on my 1966 Corvair Corsa. This is a WELL DOCUMENTED modification to the car (extant from the 70's when you bought foams in two parts mixed them in bags and quickly stuffed them where you wanted it!) It is not for structural enhancement, but rather to acoustically block an open channel from the engine room DIRECTLY to the rear seat door panel. To quiet the interior, it worked phenomenally well. Combined with some closed-cel Aircraft Firewall Insulation (from Aircraft Spruce) the interior of that car was considerably quieted down. Applying similar teqhniques to the VW Bus had NO effect, as the Germans had a bit more foresight than to allow a large hole bigger than two fists (on each side) from a fire-prone area directly to the vehicle's interior. So then you get to figure out what solvent removes/disolves the damn stuff because if it gets poked for any reason, and the 'skin' is penetrated all it does is become a big sponge to hold moisture on unprotected panels. (Look at the Cowl Piece on many early cars where that resonance-deadening sponge was applied, and then allowed the cowl to rust from the UNDERNEATH up into that fresh paint job you did just a month before...) I've not seen ONE car come by me with PROPER structural foam utilized. UNIVERSALLY it's been "Great Stuff" in the red cans, and that's not the same stuff. There is a discussion about 'urethane' foams, which is about as generic and improper as you can get! Even if you do get proper structural hard urethane foams...Don't do it. Quit arguing about something that wasn't considered---the applications are not what was in discussion and only adds to the confusion surrounding this SPURIOUS application of product from internet myth and misapplication! "Great Stuff" is not styrofoam, and it may not be a polystyrene foam any longer given gevernment mandates. The ability to get Silicone Foams has had the Corvair World change from the original Polyurethane Foams to Silicone-Based RTV Foams for the 'fire stop' capability so that the original 'soundblock' fucntion for the modification comes with a PRACTICAL fire-safing of the interior of the car. Edited October 23, 2011 by Tony D Quote Link to comment Share on other sites More sharing options...
luseboy Posted October 23, 2011 Author Share Posted October 23, 2011 seriously can we just get this thread deleted? It was a thing i was thinking of out of a whim... and it shouldn't give anyone any ideas... this stuff is bad.. even if you use the right stuff. its just pointless and has too many bad side-affects. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 24, 2011 Share Posted October 24, 2011 ACtually "Good Stuff" now makes a fire-block foam that is better than the old silicone stuff you used to have to mix. Frankly, if I was to spray anything anywhere, it would be that! I think as a poster of the thread, you could delete your own post for a period of time. After that...it persists.... It's like going pee on an electric fence. You only do it once...after that you learned your lesson and take a little more time putting thought into some things before just letting it fly! Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted October 24, 2011 Share Posted October 24, 2011 It's like going pee on an electric fence. You only do it once...after that you learned your lesson and take a little more time putting thought into some things before just letting it fly! You really had to say that didn't you! Now I have a sore side from laughing so hard as you reminded me of an incident in my youth... I was in the Cadets (sort of like your US JROTC, teenagers to young to enlist running around on army reservations with assault rifles and camo while army NCOs bark orders) while at high school, and one week excercise camp was on a farm off in the rural ***-wops. We had a full-day full packs forced march one day. Nearign the end with no more than a half hour back to base to knock off and rest at last, the squads hyperactive little ass (you know the sort, more pep and go than road-runner on meth, less brains than Wyle E Coyote in a drunken coma) came running back to the main squad from where he had been reconnitering out ahead. "Hey Corp, theres a fence up front, how do I tell it's electric, it looks electric" blah blah blah... The sarcastic response from the tired, cranky and footsore cadet corporal in charge of the squad (both corp and hyper were city boys, neither actually Knew what a bull strength fence does!) "Piss on it! you'll soon know!" The poor brainless hyperactive git was still on the ground when we reached him... Escuse me, I have to go lie down... laughing this hard is not good! Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 25, 2011 Share Posted October 25, 2011 That,kiwi, is what gets rid of little brothers... Hey, Nick, watch this: ssssssssssungh! Darn I "couldn't" get to the wire. Chris, you try! ssssssungh! Darn, I "couldn't" get there either. Well, no sense in you even trying, Nick..."you're just a little kid, if we can't reach it, YOU never could!" "OH YEAH!?!?!? WATCH THIS!!!" "sssssSSSSSAAAAAAURRRGH!!!!" See ya later little bro! I think he was scarred for life. Walking through that dewey grass, thoroughly wetted to mid-thigh. Oh yeah, the ground path must have been excellent! Quote Link to comment Share on other sites More sharing options...
EvilC Posted October 26, 2011 Share Posted October 26, 2011 (edited) Hmmm- I am trying understand facts vs what people think is stupid idea or a waste of time. We can all agree that the rockers are the strongest part of the car regarding the s30. Where I don't agree is the foaming of the rockers being a stupid idea because it won't do anything. It may be a bad idea because of rusting issues or getting it installed properly or the strength you gain doesn't out weigh the weight gain. Saying it adds no strength is completely wrong. Here is something for everyone to read - again take it with a grain of salt. I would like to see us here at HBZ start going out and doing these experiments. Even if we can't get true numbers, a visual test goes a lot further than an opinion. Lets get a s30 parts car, fill it with foam and start to cut it up. This is a writeup from Sport Compact Car magazine June 2000 where they added it to their project Nissan Z. 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. Edited October 26, 2011 by EvilC Quote Link to comment Share on other sites More sharing options...
zero Posted October 26, 2011 Share Posted October 26, 2011 I was gonna leave this one alone, mainly because of the tone of some of the responses, but Clive's post spurred me. I think WE ALL now know it is NOT A GOOD IDEA for our Z's largely for the rust and future repair issues. I don't think anyone, or at least anyone still posting, is still confused on this. With that out of the way, it doesn't mean that the thought behind it was necessarily 'stupid' or 'dumb'. Luseboy wants the thread deleted, I believe, because of the tone of the discussion, which I think is a little bit sad. Just because it won't apply to our cars doesn't mean that the discussion isn't worth having. I found the Corvair anecdote very interesting, this is how we learn. There is solid reasoning and empirical evidence that proper structural foam can be used to stiffen a chassis, even one that wasn't designed for it. I don't have an SAE subscription anymore and didn't feel like subscribing for this discussion(have an email out to my phd partner to check it out for me), but one of Art Goldman's colleagues published this paper. Here is the first page. The main topic of discussion is, again, safety. That said, in the introduction they get into the stiffness relevant to the original aim of our discussion. They added foam to an existing rocker to B-pillar joint and measured stiffness and fatigue. They, apparently, later did the proper optimization to take full advantage of the material as well, but the initial improvements were substantial(torsional stiffness by 250%!). Obviously I haven't read the article, but it certainly seems promising enough to warrant a closer look. Does anyone still have an SAE subscription? We're a forum largely of engineers, we have 'engineered' in our motto, why not have the engineering discussion. Quote Link to comment Share on other sites More sharing options...
rags Posted October 26, 2011 Share Posted October 26, 2011 (edited) NY brothers using logic on Hybrid?? What is this, 2004?? Great work guys. I like the discussion element that is now being included. Edited October 26, 2011 by rags Quote Link to comment Share on other sites More sharing options...
EvilC Posted October 26, 2011 Share Posted October 26, 2011 I agree with Will. Sometimes I think the tone in which people answer questions here isn't right. Not saying people shouldn't have thick skin but to make people feel like they have stupid ideas because they are thinking outside of "their box" doesn't say much for us as a group. I have an engineering degree - does it mean I know it all? Not at all. But my brain works when I ask questions and try to reason out my ideas. There are two people here for sure can tell you that I always ask questions, they tell me the answer (some times the answer is no it won't work) and I go an try it anyway to see for myself. We should all be doing that, seek knowledge even if we know the outcome. I honestly believe HBZ is another channel where the older generation passes on knowledge to the younger guys. Understand everyone has an opinion and I believe everyone wants to learn. So enough of the "everyone play nice" talk......we need facts! Quote Link to comment Share on other sites More sharing options...
EvilC Posted October 26, 2011 Share Posted October 26, 2011 (edited) NY brothers using logic on Hybrid?? What is this, 2004?? Great work guys. I like the discussion element that is now being included. LMAO!!!!!! I think you meant brothas Edited October 26, 2011 by EvilC Quote Link to comment Share on other sites More sharing options...
johnc Posted October 26, 2011 Share Posted October 26, 2011 I make a post here and then it goes away. Damn Admins! I agree that structural foam can help the stiffness of a chassis. But in the context of this site and this thread, its a losing proposition for a 40+ year old S30. I've cut open and repaired at least a fifteen S30 rocker panels. Every singe one had at least surface rust on the inside. Granted, that is a self selecting sample because those people brought me cars to fix rust issues, but you get my point. You can achieve better results for less money by installing Bad Dog subframe connectors and the car will remain repairable. Also, I disagree with this statement from SCC: "In any high-performance car, it is impossible to make the chassis too stiff." The Solo2 national championship FP E36 BMW is quicker without a front STB. Same is true for other cars, especially in the front. A too stiff front can overload the front tires on turn in and slow response. Sounds counter-intuitive... Quote Link to comment Share on other sites More sharing options...
luseboy Posted October 26, 2011 Author Share Posted October 26, 2011 Ok well I'm not sure if I said this clearly or not, but this is my conclusion for this thread; While foaming of certain frame rails on some chassis will increase stiffness (sometimes by a large amount), It is not appropriate for a classic car made of steel that wasn't treated sufficently, when the car already has many rust problems. That said, if i was building a low-budget race car when I didn't care about the car that much, I'd get some of the good urethane foam and foam the **** out of it. However it makes no sense on a car that you care about. And what are these subframe connectors? I've seen them mentioned a lot, but I can't figure out what they are... is it just the bad dog frame rail replacements? That seems to be what I can find... Quote Link to comment Share on other sites More sharing options...
zero Posted October 26, 2011 Share Posted October 26, 2011 Yes, the bad dog rails (the additional rear sections that are available for the 240z only) are the commercially available sub frame connectors, though many people make their own out of rectangular section steel as well. They connect the front frame rails and the rear subframe that the rear suspension mounts to, usually replacing the under floor frame rails. There are a number of threads on the subject. Quote Link to comment Share on other sites More sharing options...
rossman Posted October 26, 2011 Share Posted October 26, 2011 (edited) Sorry but I don't think there are any conclusions that can be drawn from this thread (at least not yet). I agree it's a great discussion but I'll remain skeptical until I see real test data. Test data that is not performed by an organization that is also selling or promoting the product they are testing. I still contend that the discussion here should focus on elastic (non-permanent) deformation of the structural material. Discussion or data on crushing, buckling or yielding structures does not apply. Edited October 26, 2011 by rossman Quote Link to comment Share on other sites More sharing options...
zero Posted October 26, 2011 Share Posted October 26, 2011 Apparently this was one of the upgrades Mazda did on the RX-8 when they came out with the R3 handling package. Foam filled crossmember. Mazda claims it was for stiffness rather than crashworthiness or NVH reduction. http://www.roadandtrack.com/auto-shows/detroit/2009-mazda-rx-8 Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 28, 2011 Share Posted October 28, 2011 Still waiting on that FIA ruling where you can use foam-stiffened chassis members in lieu of a roll cage... Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted October 28, 2011 Share Posted October 28, 2011 The big thing that jumps out at me in the post quoting the experiment with foaming... "Closed cell" Won't soak up and hold water... Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 28, 2011 Share Posted October 28, 2011 "Won't soak up and hold water... " Unless damaged,or inundated... Quote Link to comment Share on other sites More sharing options...
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