 | Home > Maintenance & Modifications > Foam filling for voids |
 
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| Paulv8 Member Since: 09 Jun 2013 Location: Milton Keynes Posts: 618  
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Yes. I got shot down in flames by a lot of know-it-alls, but it's still my plan. Closed cell is what I think would work. Found a half decent source once but now completely forgot where that was! V8 90...WIP
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24th May 2015 10:21pm |
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| SailingTom Member Since: 19 Nov 2013 Location: ESSEX Posts: 1720 
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Not recommended mate
seen it on a boat trailer before and made it much worse, so best sticking to dinitrol or waxoyl to protect it. Hope this helps |
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25th May 2015 5:25am |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558 
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I would avoid it , don't think the foam will seal to the insides of the chassis allowing water to be held against the sides rotting it out
ive seen it done on early austin mini sills , and I know they were foam filled as we had to replace as they had rotted personally I would stick with waxoyl , ive had land rovers for thirty years and never had to do any welding on my own ones |
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25th May 2015 6:56am |
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| Paulv8 Member Since: 09 Jun 2013 Location: Milton Keynes Posts: 618
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I used to know a guy who Had used ordinary builders foam, and painted over his chassis with Fibre reinforced builders paint. Despite my misgivings it had seemed to have worked. Certainly his 1999 disco chassis, one on the worst culprits, was totally solid. So if builders foam works, the proper stuff should do even better.
A mini or any pressed steel monocoque is not a great example as other parts of the body drain water into the cills... Like d2 door pillars where the sunroof drains. V8 90...WIP Last edited by Paulv8 on 25th May 2015 7:59am. Edited 1 time in total |
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25th May 2015 7:20am |
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| Paulv8 Member Since: 09 Jun 2013 Location: Milton Keynes Posts: 618
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Interesting comment on the boat trailer sailing Tom, any idea what type of foam - what colour was it? And was it regularly submerged in what type of water? V8 90...WIP
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25th May 2015 7:22am |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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you will get water in the chassis and it wont dry out anywhere near as good as a open chassis
my last defender was a 93 and waxoyled from new and 100% as new when I sold it if you are foam filling a older chassis then you would need to rust proof first anyway as the inside will be rusty already sorry the idea seems good but in practise I really really don't think it will make it better the only other thing ive always done is plug the holes on the outside of chassis stopping road mud/dirt/salt/water etc getting in , leaving the bottom ones open |
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25th May 2015 7:31am |
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| X4SKP Member Since: 29 Nov 2013 Location: Berkshire Posts: 2295 
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Hello Shax
I have specified this for transport and marine applications to meet buoyancy, thermal and sound insulation requirements (i'm an industrial designer). I would not use it on a Defender Chassis 'and other voids'. In general there are two approaches to Box / Void Chassis / under body design, water tight...sealed often a tubular / space frame arrangements, and those designed to be 'semi-open' sometimes carrying and protecting 'services', electrical, fuel, hydraulics etc. The Defender is obviously intended get wet and self drain... With good internal treatment, updated from time to time this I believe is the best approach on a standard issue Chassis (Galvanised Chassis aside). This approach requires flushing out on occasions, to expel road salts in particular. An expanding foam will not seal a Defender Chassis, and in my view will almost certainly make water ingress and retention worse, capillary action probably taking water deep into unsealed routes. These Foams are also generally rigid when set the Defender Chassis whilst apparently 'rock solid' does move around under load this will further open up water ingress routes. Rubber Plugs will also not seal up a 'foam filled' Defender Chassis (IMO). Your call but proceed this caution on this one... not of immediate concern but also if corrosion does set in and welding is required down stream then a foam filled Chassis (even with a fire resistant foam) will cause further issues. SKIP https://www.defender2.net/forum/topic83242.html |
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25th May 2015 7:37am |
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| Shax Member Since: 05 Oct 2010 Location: London Posts: 391 
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Thanks to everyone who commented... The idea is now permanently on hold!! ... ,-------,
.. I [__][_]|__ .. I __ |"_|"__| .. "(o)====(o)" ^^_-^-_^-^_^^^^^--^^^^ PAUL G7ALW 14.200 USB 26FB458 / 27.275 SSB |
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25th May 2015 9:59am |
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| Paulv8 Member Since: 09 Jun 2013 Location: Milton Keynes Posts: 618
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Fyi, taken from another site when I researched this.... its not such a stupid idea
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. http://image.sportcompactcarweb.com/...0zx08_zoom.jpg http://image.sportcompactcarweb.com/...0zx06_zoom.jpg They way I got it was actually cheaper. about 100 total. Basically, do a google search for "Handi-Foam" Then find the manufacture and they will send you to a distributor in your area. Probably at your local industrial park. They sell a II-12 can, a II-25 (IIRC) can, and then a big box. You need a couple II-25 cans and maybe one or two II-12's. It's called Handi Foam, Two-Part Quick Cure Sealant Kit. V8 90...WIP |
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25th May 2015 10:51am |
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| Supacat Member Since: 16 Oct 2012 Location: West Yorkshire Posts: 11018 
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Paul - the article is interesting but is about the application of foam for structural rigidity rather than corrosion protection. it also talks about unibody construction so appears to be a completely different setup to that of a defender with a true chassis.
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25th May 2015 2:39pm |
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| Paulv8 Member Since: 09 Jun 2013 Location: Milton Keynes Posts: 618
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I understood that. It refers or links to manufacturers that actually do do it, which is why I referenced it as not such a silly idea.
I asked d further questions because direct experience is interesting and may help actually work out whether this is a feasible idea, rather than the armchair expert variety.variety of opinion which generally appears negative about everything. As I said above, I have actually seen this done on a 99 disco with good results and cheap foam. Surprisingly! V8 90...WIP |
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25th May 2015 8:14pm |
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| Paulv8 Member Since: 09 Jun 2013 Location: Milton Keynes Posts: 618
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And presumably corrosion is an issue for the manufacturer to consider when choosing foam as a structural strategy? V8 90...WIP
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25th May 2015 8:17pm |
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| SailingTom Member Since: 19 Nov 2013 Location: ESSEX Posts: 1720
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Not sure on the make as was bought for the boat on it. was a grey/white, but mainly brown with rust  went to the scrap man |
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25th May 2015 9:47pm |
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