Gap filling foam stuff

Think that's the stuff they used to put in Mini sills, don't recall it doing much good in them so YPYMATYC. if you do fill 'em up be very very careful about subsequent welding in the area. It gives off ooh nasties when heated.

Bad idea... as much ventilation as possible to dry the undercarriage out.

Also allows judicious application of your chosen preserevative... never get chassis rot around a leaking gearbox!

Foam will only hold in water and crud.

Beware the car thats always been garaged... a damp car locked in a garage will rot much quicker than one left out to dry in the circulating air.

Lee D

That's a good point about the welding - maybe not such a great idea after all...

AC.

Mind you... welding onto/into the chassis is generally a pretty bad idea anyway, unless you REALLY know what you're doing, IMHO.

I don't think that welding is the major issue.

Unless you can guarantee full adhesion to all surfaces you're likely to make things worse rather than better. Even with new components and scrupulous attention to detail you're very unlikely to achieve that.

Far better to rely on well-drained cavities with lots of ventilation. By all means help things with appropriately applied wax coatings. Keep the drain and ventilation holes clear.

In article , Andrew Cleland writes

If you mean polyurethane (yellow or tinted green), it uses water to catalyse the curing process. In the complete absence of damp it doesn't expand too well. Once cured though it's pretty tough and inert although it is slowly attacked by UV (not as fast as I expected though).

I think the issue real issue though with an existing sill/crossmember would be that it would trap water, causing corrosion to go at a faster rate than normal. Perhaps if you Waxoyled it first, then foam filled it it would work well.

Fifty cans later, you might have the world's first Amphi-Landy...

That's actually a great idea! An amphi-landy... it'd make those river crossing a breeze! No more hyrdraulic-ed engines! (And I assume you're talking 50 cans of expanding foam, rather than the malt and hop flavoured foam).

Seriously... there's a 2-pack foam used by surfies/boaties that expands to

Hey... if it didn't work, at least you'd have the world's first 2 ton surf board, with windows no less.

In article , asdf writes

Both, naturally :-)

Same chemistry. I can't remember how it's done in the foam cans - inhibitor, I think - but I'm morally certain it's the same. The people who used to sell glass fibre products here (Strand) sold it too, for buoyancy for Kayaks etc.: a two-part resin that went crazy when you mixed them.

Whatever happened to Strand - useful stuff!

There's a nifty system for polyester resins, with a two-part giant syringe and a mixing nozzle (has a spiral divider in it. The chemicals stay separate until the last minute then get mixed when you pump them out, and you just throw the nozzles (any left in the tube can be used later). They glue houses together with it, and it goes off in seconds. See:

Gun:

Indoor surfing... eat yer heart out, Nintendo Wii!

Nice!

yeah... but 2 ton surfing? eek!

On or around Sat, 28 Feb 2009 21:30:29 +0000, Andrew Cleland enlightened us thusly:

depends if it can wick water in there. If it's genuinely waterproof, and it's dry inside to start with...

I'm pretty sure that "can foam" is nothing like a closed cell structure, so it will be porous. Even if it wasn't the chances of there being a good seal between the iron work and foam are minimal I would have thought.

On or around Sun, 01 Mar 2009 19:42:59 +0000 (GMT), "Dave Liquorice" enlightened us thusly:

yeah. I reckon squirting waxoyl or suchlike inside will be a better bet. Gonna have a go at that on my new thing, might help it last a bit longer. Chassis looks good for a 10-y-o, but has a bit of surface rust, so likely to be some inside as well.

Good Idea, but you must use closed cell foam (not the cheap builders stuff!) or it will absorb water after a while.