Originally Posted by
BoxedFox 
That's actually a slightly different kind of foaming. More specifically, it's a different kind of foam. Great Stuff is a highly aerated, quick cure foam that's great for stopping heat and damping noise. It's not so good for structural purposes though.
Not to say that Brennan did anything wrong. I think Brennan made the right choice of materials there. I'm just not sure if it'll work for what Shawn B is looking to do.
Agreed, I have come to hate constant squeeks and rattles, and it looks like the Great Stuff does the trick.
It wasn't "didn't want to use" Great Stuff, hell using that would be far easier. Cheaper too. And apparently would work for sound deadening rattles quite well.
Brennans write-up and pics is terrific for that application. Good work.
Actually my friend, I am glad you brought up the subject of "other foams."
Originally Posted by
classicaddict i have used great stuff quite a bit to stop trunk rattles and things of that nature. the foam shawn is going to use is quite a bit more hardcore and i dont feel as tho a simple pass of a hobby knife will trim it off. also, great stuff doesnt REALLY stick to paint, you can buff it off, shawns foam is much more comparable to a glue.
Bingo.
And I think it is more of a saw, chisel perhaps, grinding wheel kind of removal. Nor does it come off with any solvent.
"Glue" might be a good analogy, two-part epoxy type glue. With lots'a bubbles in it.
Mike K calls it "catalyzed rigid structural polyurethane foam."
Here's an edited version of the article from SCC magazine (link to full article in first post):
Originally Posted by
SCCFoam-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.
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.
Perfecto....
Future plans include a CSK/Hyperco based suspension (currently AGX/Hyperco based) on my stiff as a motherf*cker chassis. I know that will provide highly elevated levels of susupension performance, no doubt. Secondarily, I *believe* that suspension on my uber-rigid chassis will allow stock-like comfort levels. The best of both worlds. We shall certainly see.
My "ideal Classic suspension" would be akin to the modern-day Mazdaspeed 3, Chevy Cobalt SS, or nearly any BMW coupe. Every bit as capable
and just as comfortable.
To refresh, here is the other one I ordered:
8 LB Density Urethane Foam
Common Applications: This 8LB density foam is extremely hard and rigid, like that of a soft wood. Your fingernail can penetrate its skin, however it cannot be dented by hand. Uses include casting, carving, sculpting, sign making as well as areas where an extremely durable and rigid foam is needed for support. More questions? [Try our Foam FAQ.]
Cat No. Kit Size(net weight) Approx. Coverage Price
FOAM-0804 4 LB Kit 1/2 Cubic Foot $20.50
FOAM-0816 16 LB Kit 2 Cubic Feet $62.00
FOAM-0880 80 LB Kit 10 Cubic Feet $244.00
5 or more kits of the FOAM-0880 $232.00 / Kit
Product Information:
Free Rise Density: 8.0 lbs cubic ft.
Expansion Rate: Approx. 8x Liquid Volume
Buoyancy (flotation): 54 LBs per Cubic Ft.
*Physical Properties:
Parallel Compressive Strength: 250 psi
Tensile Strength: 225 psi
Shear Strength: 130 psi
Flexural Strength: 350 psi
I am glad that the foam will quell noise and rattles in the vehicle. Desirable benefits, no doubt. Bonus.
However, my application is primarily a chassis/suspension upgrade. I want to greatly increase the vehicles torsional/structural rigidity and overall chassis strength.
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