Re: [Amc-list] Bedliner/foam in rails

[Wrambler242@xxxxxxxxxxx]

I'd forgotten all about the fact that even closed cell foam is not 100% closed cells.
It retains moisture.
I once had a boat that a section of floor rotted in.
when I pulled it out I found a gigantic water logged chunk of foam below it.
The boat manufacturers inject the foam for floatation. Works great for many yearsbut eventually waterloggs having the oposite effect.
   Should this happen in a frame rail the results would be disasterous. I'd imagine it would be akin to stuffing the rail full of wet soggy leaves and letting it sit. Not pretty...

--
Mark Price
Morgantown, WV
1969 AMC Rambler, 4.0L, EFI, T-5
2004 Grand Cherokee Laredo, 4.7L, Quadratrc II
" Chronic Pain Hurts"

 -------------- Original message ----------------------
From: "oldcars@xxxxxxxxx" <oldcars@xxxxxxxxx>
> I think that in the early 80's the factory started filling in the frame
> rails with paraffin wax, to keep out moisture and dust, as a part of the
> multi-step process for reducing rust. 
> 
> Perhaps this could be tried, if you could get a clean and perhaps treated
> surface on the inside of the frame rails?
> 
> Original Message:
> -----------------
> From: Frank Swygert farna@xxxxxxx
> Date: Wed, 19 Dec 2007 15:28:43 -0500
> To: amc-list@xxxxxxxxxxxx
> Subject: Re: [Amc-list] Bedliner/foam in rails
> 
> 
> It's one of those "sounds good in theory, doesn't work in practice" things
> Don. The problem is the foam isn't 100% moisture proof. So what little does
> get in can't get out, and you end up with worse rust (in spots) than if the
> area was left open with good drain and air holes. The best thing you can do
> is enlarge the weep holes near the bottom of the rails (there should be
> some from the factory, sometimes just small gaps in seams that are hard to
> find) and make sure air can get in from the top. You can't keep 100%
> moisture out, so the idea is to make sure it drains or drys out instead.
> That doesn't hurt a painted surface, standing water does though! Most
> chassis rails rust out due to fine dust that collects over the years
> retaining moisture. If you could keep everything washed out it would be
> better than foam! Coating the inside with something to protect the bare
> metal/primer then having adequate drain/air holes is the key. 
> 
> ----------------
> Date: Tue, 18 Dec 2007 16:04:06 -0500
> From: Don <don_nsx@xxxxxxxxxxxx>
> 
> Why not fill the channels and subframes with expandable foam like they use
> to seal house foundations.
> Its not the same as the stuff they're using in new cars but it would keep
> the moisture out and that would slow the rusting process.
> I guess it helps with sound deadening too.
> 
> -- 
> Frank Swygert
> Publisher, "American Motors Cars" 
> Magazine (AMC)
> For all AMC enthusiasts
> http://farna.home.att.net/AMC.html
> (free download available!)
> 
> 
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