Waste of time and money or brilliant body stiffening/rust prevention?

[318 Six Pack]

Was checking out again the areas I applied POR-15 about six years ago. Was really using it as a stop-damage method until I could cut out and have new patches welded in. Especially impressed where I used the thick POR squeeze-tube product.

However, the stuff worked so well I was thinking about covering the bottom of the floor pan in POR-15 and glass, after removing the rust, welding any rust holes, installing torque boxes and frame rail tie, and cold galvanizing. Still plan on using bed liner as final layer no matter what is between it and the steel. Of course, would keep drain plug holes clear so plugs can go back in, as well as all of the bolt holes, etc.

Different item, I saw some car show where the builders filled the rockers with an expanding foam for stiffening. I think it was a Bricklin build. Anybody tried or seen this on a B Body?

 

[fatecaptured]

I would think the foam in the rockers would be a bad idea myself.

 

[Cranky]

And I don't see how foam would stiffen them.....if any, it wouldn't be much.

 

[Propwash]

I would think the foam in the rockers would be a bad idea myself.

I agree.


Foam = porous = air = trapped moisture = rust = pissed off = drinking = swearing = settling for a prius

bad math amigo.....


Body stiffening with foam? Sounds like voodoo magic to me. Try your subframe connectors and torque boxes route..bullet proof.

 

[318 Six Pack]

I would think the foam in the rockers would be a bad idea myself.

That is what I thought when I saw someone using household expanding foam in some Japanese car. This stuff in the Bricklin was a two part product. If it hardens up like POR-15, I could see it doing a lot of good at the start. Not so sure about long term.

 

[Photon440]

I've been interested in foam stiffening for quite awhile. I first experimented with expanding foam in a Plymouth Arrow about thirty years ago, just because I had a bunch of the stuff (two part liquid) and wanted to fool around with it. The panels that I treated sounded much more solid, no tinny econo car rattles any more.

Anyway, I've since looked at it again more recently, especially since a lot of car manufacturers are employing it in certain areas. The use of foam greatly quietens road noise, and is a pretty good structural stiffener. The important thing is to use closed cell foam to keep out moisture. I was thinking of using the same type that you'd use to fill voids in a boat hull to keep it buoyant.

Rather than repeat what I've found, I'll add some links. One of them is for SAE paper 1999-01-1785, which was written by Chrysler back in 1999.

http://www.mwsmotorsports.com/z32/foam/1999-01-1785.pdf

http://papers.sae.org/1999-01-1785/

http://www.subrosa.com.my/automotive_foam_chassis_stiffening.html

http://www.youtube.com/watch?v=oCDwDhdTd3c

http://forums.nicoclub.com/chassis-...t-1-qualitative-result-56k-no-go-t270721.html


I will be foaming parts of my car. I'll probably take pictures, but there's no time frame right now.

-=Photon440=-

 

[747mopar]

Bingo "closed cell foam" he's absolutely right, open cell absorbs water and closed is just that "closed" and doesn't absorb water. My brother is fixing a totaled 2013 Dart right now and it has foam all threw the rear subframe? I personally wouldn't do it, even if you use closed cell foam you could still end up trapping moisture between the foam and metal besides I don't think you'll gain much by doing it.

 

[318 Six Pack]

I've been interested in foam stiffening for quite awhile. I first experimented with expanding foam in a Plymouth Arrow about thirty years ago, just because I had a bunch of the stuff (two part liquid) and wanted to fool around with it. The panels that I treated sounded much more solid, no tinny econo car rattles any more.

Anyway, I've since looked at it again more recently, especially since a lot of car manufacturers are employing it in certain areas. The use of foam greatly quietens road noise, and is a pretty good structural stiffener. The important thing is to use closed cell foam to keep out moisture. I was thinking of using the same type that you'd use to fill voids in a boat hull to keep it buoyant.

Rather than repeat what I've found, I'll add some links. One of them is for SAE paper 1999-01-1785, which was written by Chrysler back in 1999.

http://www.mwsmotorsports.com/z32/foam/1999-01-1785.pdf

http://papers.sae.org/1999-01-1785/

http://www.subrosa.com.my/automotive_foam_chassis_stiffening.html

http://www.youtube.com/watch?v=oCDwDhdTd3c

http://forums.nicoclub.com/chassis-...t-1-qualitative-result-56k-no-go-t270721.html


I will be foaming parts of my car. I'll probably take pictures, but there's no time frame right now.

-=Photon440=-

Great stuff! And for the record, I was only considering closed cell products.

- - - Updated - - -

Bingo "closed cell foam" he's absolutely right, open cell absorbs water and closed is just that "closed" and doesn't absorb water. My brother is fixing a totaled 2013 Dart right now and it has foam all threw the rear subframe? I personally wouldn't do it, even if you use closed cell foam you could still end up trapping moisture between the foam and metal besides I don't think you'll gain much by doing it.

If I go with closed foam, it will be after all the rust is cleaned out and all the metal is covered with cold galvanizing and POR-15.

 

[texas69bee]

I agree with propwash. I bought a 69 bee that had damage to the lower rear quarter panel. The previous owner used greatstuff to hold it away from the trunk extension to try and maintain its shape. Long story short, it looked like crap and anywhere there was greatstuff there was rust.

- - - Updated - - -

I agree with propwash. I bought a 69 bee that had damage to the lower rear quarter panel. The previous owner used greatstuff to hold it away from the trunk extension to try and maintain its shape. Long story short, it looked like crap and anywhere there was greatstuff there was rust.

 

[Photon440]

'Greatstuff' isn't the 'right stuff'. You need the two part liquid closed cell foam for the job.

 

[Propwash]

Pretty neat reading, thanks for posting. Was good to get informed about the product. Looks like some cutting edge stuff, but there's a lot offset applications with the technology that really doesn't fit in the world of our old mopars. One is overall closed tube chassis design throughout the entire vehicle, which our cars don't have. We have closed frame rails, but with 14 steel gauge boxing, the stuff is pointless. New cars, 18 gauge frame or aluminum tubing, yes...they could use some reinforcement. Our A-pillars, they're nothing the size of the new cars. If you have sawed into them, you'd notice you would be trying to fill a 1-1.25 dia. area. I couldn't imagine much, if any added support. And if there was support, it would be in structural impact resistance, not rigidity for handling capabilities. C-Pillar, you can't fill it, it's not boxed. B-Pillar (if your car has one), is half open, but real beefy anyways. So where does that lead one to fill, the rockers? So on to my next point...

Another factor and it's a big one, is that the factory is filling these tubed key areas, brand new at the factory. Are they using an adhesion promoter or a special primer to bond with the foam for a tight seal? It does not specify, but I imagine they are. Also, are the MFG's thinking about the long haul and corrosion issues down the road? So brings the point of how would you approach that on a 40-50 year old mopar. Without a doubt, unless your car has been ripped completely apart, your frame rails, torsion bar crossmember and rockers are filled with rust, mud, dirt, grime, mice nests and whatever else a half a century has thrown at it. If you have pulled these areas apart, you know what I mean. So if you don't have plans to rip it all apart, blast it clean, treat it, apply a coating that will take to the foam and help deter any impedance area for moisture/rust to form, is it a good idea? Absolutely not. It doesn't matter if it's open cell or closed cell because it just became a cancer cell. Applying any of that over any kind of rust, dirt, grime, grease has just created the perfect breeding ground for rust to thrive and grow.

I'm not cutting down the product, the theory or anyone's plans down the road, I actually think it's pretty neat stuff. IMO, I don't see where this stuff really fits into our application, with 40-50 year old cars, with completely different core chassis designs, that probably have a lot of skeletons in the closet living in any closed areas of the car. I also wonder about it's ability to not promote corrosion. You do not see this stuff in aircraft. The biggest point in airframe design is to build the lightest structure possible, with the most support/rigidness as achievable. That being said, you would think all the aircraft MFG's would be using it, but they don't. Why? Myself, I would either guess it's not all it's cracked up to be, or they're worried about corrosion issues (which is a big, big deal in the aviation world), but....that's just me speculating.

Thanks again, it was neat to learn about the stuff and I can think of a few other applications where this stuff could be quite useful.

 

[Photon440]

>edit<
You do not see this stuff in aircraft. The biggest point in airframe design is to build the lightest structure possible, with the most support/rigidness as achievable. That being said, you would think all the aircraft MFG's would be using it, but they don't. Why? Myself, I would either guess it's not all it's cracked up to be, or they're worried about corrosion issues (which is a big, big deal in the aviation world), but....that's just me speculating.

Thanks again, it was neat to learn about the stuff and I can think of a few other applications where this stuff could be quite useful.

While at one time true, these days there are applications for airframe design that do use foam. Where in the past it was common to use honeycomb structures to stiffen panels, foam is now being used. Both the Boeing 787 Dreamliner and the Airbus A350 XWB have foam in floor panels, parts of the wings and rudder and skin sections. As well, a great deal of these aircraft are composite instead of aluminum. Aside from the heavy airframes, foam is quite a common stiffener on home-built craft, especially when using fiberglass or plywood over wood stringers. Gliders often use foam as a stiffener. Carbon fiber is strong in some directions, but as a flat sheet on a wing is needs stiffening.

And of course it wouldn't be a good idea to foam over existing rust or dirt. Whether new car manufacturers do any special prep, I don't know. But I do know that two part foam is extremely sticky and I've found it nearly impossible to remove many years after application, often requiring sawing or grinding to get it off.

Just for kicks, I built a dog house (about 1982) and it had a floor raised 2" off the ground, so I filled the gap with foam, hoping the insulation would keep my dog warmer. As many years went by the wood eventually rotted away on the sides and roof, but the floor which was in contact with wet earth all the time stayed solid. That was the only wood that didn't rot.

 

[Propwash]

Interesting to know Photon. I do know the foam in a dreamliner & air bus wings is inside the fuel cells, and is there to prevent agitation and aeration of the fuel, just like many other aircraft. I don't believe it's directly incorporated into the into the ribs, spars and stringers or applied directly to the skin of the aircraft. Doing so would hamper any type of hourly or annual inspection and/or maintenance work on adjacent systems. I could see a floor panel, but honestly in semimonocoque fuselage design like the 787 & Airbus, the floor holds no structural value, just seats and people. Now a rudder, I could see that, being it's a sealed tight flight surface, and a throw away. That must be very new technology, because Boeing/McDonnell have utilized honeycomb in their rudders, vertical and horizontal stabilizers up to this point, that includes the the late model F-15's and F-18 Superhornet's. We have two offices that deal with Boeing daily over on the west coast, i'm gonna have to pick there brains a bit I guess, because this is some pretty intriguing info. I try to keep up with all the new aviation trending, being a pilot (just PV VFR/IFR/Multi), expired A&P and ex-USAF aircraft mechanic, but technology is changing quickly. My wife's company actually makes the circuit boards for the black boxes for the dreamliner as well as the circuitry for Rockwell/Garmen aviation GPS and NAVCOMM systems. She's an airplane nut as well. As far as the composites, IMO, I wouldn't say it's a great deal, more like a smaller minority. Smaller sport class MFG's out there like Diamond, Cirrus and a few others do make full composites these days, but I would say a good majority are still aluminum. Obviously Boeing is taking great stride all together with composites on the dreamliner. With the home built stuff, well those guys live under a whole different part of 14 CFR. When the only one who can annual/inspect a plane (for the rest of it's life), is the builder, well...buyer beware..lol Seen some pretty scary stuff.

 

[Photon440]

'Glass over foam is good enough for Burt Rutan.



But I'm straying from the original topic, which didn't include fiberglass cars or planes. All I can say is that based on my experience, (mostly in the rail freight industry) foam hasn't been an issue as far as introducing problems with corrosion. Rail cars aren't particularly rust-proofed, rusty old boxes are written up for destroy all the time where I used to work with 'age and decay' being the reason stated on the form. But when these cars are dismantled, any areas that used foam were usually still pristine. Not all cars use it, but I've seen foam as stiffeners in sliding doors, in floors and walls of insulated produce cars, and as a seal for roof seams. Scrape the foam off a rusty box car, and good steel is underneath.

I appreciate that you have more contact with the aero industry, Propwash. (I knew what your name meant the first time I saw it. I'm just an armchair enthusiast in that area. I won't take up more of the OPs space with it. Feel free to PM if you'd like to continue with me.

To conclude, I'll have no issue with introducing foam to areas of my car. I've worked with foam for years. Even if there is no appreciable stiffness added, I'm pretty sure it will be somewhat quieter. I have no concerns about rust forming between the foam and the steel.

 

[Propwash]

Thanks Photon, and sorry for straying off the point myself. I do find your posts here informative and have learned plenty from your articles and input. It is pretty neat technology. I can definitely see where you're coming from with certain specialty foams, properly applied, safeguarding its base material. Heck, the only usable metal that was left on the underneath of my roadrunner is where there was the factory undercoating was able to survive. The paint was still shiny underneath it. So that goes to show, that the proper materials, properly applied will safeguard the surface it's bonded to. I'm glad you took the time to inform the rest of us on the product and your experience in the past personally and in your profession. Obviously you have a passion for planes as well....Most folks have no clue who Burt Rutan is. If you ever want to chat off board about aviation, feel free to contact me. Myself, I can't seem to ever shut up about it lol. (kinda like mopars). But agree, talking about it here on the OP thread isn't the right place. Thanks again and enjoy the rest of your weekend.

 

[sleepar]

For a quick fix of rusty rockers the foam caused more rust because it wouldn't let water drain out and kept everything damp.... glass boats use foam and they get heavy with water too. I would steer away from foam fillers closed or open... I can see a fire hazard from welding neer it in future repairs.. air plane technology is the way to go.... I wouldn't want to hurry up and have to remove it due to some UN seen circumstance... like electrical wireing. The concept is sound build a Styrofoam cooler around you to keep noise and excessive temperature out.

 

[Malicious]

Its a good idea, but most of the points here are valid. I've found the raw liquid foams to be extremely sticky. Most of the time you need to use a releasing agent to keep it from bonding to the surface that you're injecting it to. Similar to what a fiberglass maker does.

Also closed or open cell, you will find that uncut foam will have a 'skin' to its outer. 99% of the time that is its own sealed skin so no water will get into it. So while I would stick to closed cell foam, you should find that the skip keeps the moisture out anyway. Once you cut it or damage the skin, all bets are off. You call raw uncut foam a 'Bun'. A completely random fact.

Another, not all foams are equal obviously. YOu want an increadibly stiff one, a structural type foam. Extremely high hardness and preferably density, althought the higher the density the heavier it is, so it kind of counter acts the weight saving...

Only other thing I can add is, foams are inherently flammable. But most foams have an added fire retardant added. Foams that meet California fire regs will have a good amount of retardant in them. The only problem is, the more 'filler' (non foam compounds) you add the weaker the foam is. I'd just use it away from areas that might flame out!

Also keep Styrofoam away from gasoline, that's how you make napalm! ;)

 

[318 Six Pack]

Its a good idea, but most of the points here are valid. I've found the raw liquid foams to be extremely sticky. Most of the time you need to use a releasing agent to keep it from bonding to the surface that you're injecting it to. Similar to what a fiberglass maker does.

Also closed or open cell, you will find that uncut foam will have a 'skin' to its outer. 99% of the time that is its own sealed skin so no water will get into it. So while I would stick to closed cell foam, you should find that the skip keeps the moisture out anyway. Once you cut it or damage the skin, all bets are off. You call raw uncut foam a 'Bun'. A completely random fact.

Another, not all foams are equal obviously. YOu want an increadibly stiff one, a structural type foam. Extremely high hardness and preferably density, althought the higher the density the heavier it is, so it kind of counter acts the weight saving...

Only other thing I can add is, foams are inherently flammable. But most foams have an added fire retardant added. Foams that meet California fire regs will have a good amount of retardant in them. The only problem is, the more 'filler' (non foam compounds) you add the weaker the foam is. I'd just use it away from areas that might flame out!

Also keep Styrofoam away from gasoline, that's how you make napalm! ;)

That stuff Photon440 provided video for looks like what I was hoping for. As for weight, some is coming out of the car and in this case some might be going back in With the engine upgrades it will not be a huge deal, and I don't race anyway.