Fill Body With Foam?

[Guest TKR514]

There are a LOT of cavities in the body of the 280ZX(A/B pillar, side rails, rear quarters, etc). Can the filled with "foam-in-a-can" to deaden noise?

Will it trap or promote corrosion if they are filled? Will it help prevent corrosion? It would seam a cheap/easy way to quiet the interior and reduce rattles, also low in weight...

[blueovalz]

This, to me, would be a sure fire way to end up with a rust heap.

[Guest TKR514]

How so? I'm preping and painting those areas so it will start out rust free. Since rust needs air and moisture, woun't this keep both out? Also I believe that Honda is doing this to give thier cars a "solid" feel...

[Guest Anonymous]

Terry has a good point.. You can use closed cell expanding foam but I would not want to take the chance on it much less open cell(sponge) foam check this out for foam web page

[Guest TKR514]

I might do a test. Put the "foam-in-a-can" between 2 metal plates and leave the assembly outside for a month or two. My bet is that the metal surface that's stuck to the foam will be perfectly fine while the "exterior" metal will be the part that shows corrosion....

Spray foam seems to hold up very well when exposed to the elements in the cracks on our house for the last 10 years, in the sun and dampness. "Might" be even better in the dark areas in the car....

[SpeedRacer]

I don't know what kind of foam they used but GM used to fill the voids between the supports and body on their G van's to prevent "oil canning."

 

I saw a couple of rusted vans and they rusted up to the area that was foamed but not where the foam was.

[John Greenslade]

I suspect even if you seal this well that there will be some form of galvanic corrosion resulting from the difference in electrical potential between the steel and the foam (which will invariably have some moisture content). similar to what happens between two different types of metal. If you wanted to avoid problem you could probably coat metal with POR 15 if you have a way to spray in applicable areas, and then foam.

[Guest TKR514]

Galvanic corrosion between the foam and metal?

Kinda remote since the spray foam is electically an insulator. Also, won't the lack of air around any potential site of rust deter future formation? If oxygen is used up to make rust, preventing the free flow of air to that spot should stop it from growing?

[aviatorx]

The idea of using a urathane foam for acoustical / structural purposes has come up in the past, but I don't think anyone has taken the time to either trial or further research the issues beyond speculation. I do know we've banged around the concept of using a 2 part urathane based foam for stiffening the frame via the frame rails and rockers, but it seemed the concensus was that the problem was insuring the foam actually adhered to the chasis to provide a proper load path...otherwise you are just filling a void for sound deadening and possibly creating a home for rust to build.

 

I like the idea of using a POR 15 type product to coat the metal prior to foaming, but I think that if you are seeking anything other than sound abatement you are better off looking for another solution.

 

Restorations abound with wax/oil mixtures in auto cavities (frames mostly) as a rust inhibitor, but there is an obvious weight penalty in doing that. I'd be weary of foaming a z car that's a daily driver and exposed to the elements - but if it's a garage queen, why bother?

 

TRK514 - do it up and let us know!

[blueovalz]

A better quality expanding foam may work fine, but here are my observations. The cheaper expanding foams will, with age, shrink or contract, which eventually leaves one side or both (in the case of a quarter panel) with a space between the foam and the metal. Water gets into this area, and with little air circulation, will eventually find an open in any protection applied to the lining, and cause rust. The foam idea IMHO will work, but I feel that for it to be effective and not cause more problems later on, it must be sealed completely. What I eventually did was use an undercoating to seal any cavity that had the foam in it (nothing worse that wet foam that starts getting stale and stinky too). so that it was a sure thing that water was not going to be exposed to the foam. Open cavities that are properly protected and allow constant air flow and circulation are good for metal protection. The foam, from my past experience, if not carefully applied and then protected, will cause big problems later on.

[BLKMGK]

There are some foams made for this - talk to a body shop. Sport Compact used it on their 300ZXTT to stiffen the chassis - it's called structural foam.

 

One thing to note - welding of any sort later on will be greatly complicated by the presence of structural foam. I'm sure it can ignite although it's supposedly fire retardent - a welder can get it pretty hot.

[ToplessZ]

I believe someone else here posted this once and I had also thought about doing this. The idea was to take a heavy duty garbage bag and insert this as a liner into the body cavity to be filled and then fill it with the foam and seal off the top. I think this could work. Any other input guys...

[Guest TKR514]

Well... I don't see a difference in using sound deadening mats on the floor and closed-cell expanding foam in the body. If it's a problem with foam filler, then closed cell mats on the interior would be an equally rust attractor. Soooooo.... leave all metal painted and un-covered for maximum rust prevention?

[Guest Anonymous]

I do not care how Ya do it..... metal SWEATS. and you could possibly have moisture accumulate between the foam and the sheet metal. I have considered it too but always held back becuz I could not be convinced of the wisdom of sealing metal with foam that can break down over a period of time..

[Helldrives]

Has anyone actually used the "Ridged Foam" for making a stronger subframe? I am starting to hear more about it with some of the more modern Japanese cars.

[Helldrives]

Here are some sites that a budy told me about.

 

http://pagebank.sun-inet.or.jp/%7Ebellco/essh.htm

 

http://www.foamseal.com/auto_aftermarket.htm

 

http://arrakis.mk84.com/repo/HotVersion_PU-Demo.zip

 

The last link is a zipped MPG. English subtitles are in white at the very bottom.

[Mikelly]

I think Terry's comments are spot on. You will more likely than not create a place for moisture to collect and cause more serious rusting issues. You might be successfull doing it, but do you really want to take the chance with your Z?

 

Mike

[280Zen]

I would think that if you cover the metal parts with POR-15 then you would not have the rust issue and then could use the body foam. Last months issue of Turbo had a blurb on body foam.

 

Ziebart coating also works very well against rusting, The origional owner of my 83 280zx had the car Ziebart coated. The only spots that actually showed rust was where the paint chipped away on the front hood and top by the window. The rest of the cars undercoating and interior metal is in perfect condition.

 

3M also makes a spray on coating that works very well against rusting, Can't remember the name of the product though.

[Guest KraZ4spd]

Whay was that stuff they used on Monster Garage to fill the bumpers of the Swamp Bug. That stuff was completely water resistant.

[blueovalz]

I hate nit-picking, but water proof and water resistant are two different animals. If the metal was completely sealed well, then I guess "foaming in" will not cause the retention of water to be a concern. I did foam in my fiberglass quarters, but it was a second attempt in which I learned that it must be sealed water tight, it will shrink slightly with age, and that expanded foam must be carefully applied. A minute amount of pressure per square inch (from expansion), applied over a broad area, will produce enough pressure to distort even the most sturdy of structures.