PDA

View Full Version : Expanding foam - waterproof?



DRFT - 86
11th May 2005, 08:59 PM
Does anyone know if this stuff is waterproof......or does water soak into it at all?

reason I ask is... where my loom goes through the firewall..the rubber gromett is fucked.....(I have one to replace it but that means I would have to mess around heaps just to get the loom through it as there is no way of disconnecting one end exactly) so...I was thinkin of filling the cavity around the loom with expanding foam to stop water entering.

dont want to use it if it holds water....as this will no doubt lead to rust....

or does anyone have a better idea than this....?

cheers

ae86levint
11th May 2005, 09:07 PM
silicone, don't try and paint it tho. expanding foam is full of air bubbles not sure if it will hold water tho.

DRFT - 86
11th May 2005, 09:23 PM
yeh it has been siliconed b4, but it hasnt worked that well.......hmm I am pretty sus on foam been waterproof though ahy......it might have to be silicon again......

also how can you tell if a silicon is non-acid bearing..... (I have a tube at the moment but it dosnt say anything about this)

RobertoX
11th May 2005, 10:08 PM
ask funk doc, his whole car is foam

NickAE86
11th May 2005, 11:03 PM
in my experience not really. The foam itself is but its the seal between the foam and the surface you're applying it to isnt. I've had to use the stuff at work when mastik hasnt been available and in certain areas where water (constantly) is present some very slow leakage has occured but for what you want to use it for it'll be fine

make sure you clamp/cover the area after you've filled it to contain the foam and stop it from going everywhere

if you can get your hands on some mastik its good stuff...its black, sets like rubber and is fire rated

Medwin_3sGTE_AE86
12th May 2005, 12:29 AM
Completely water proof... the stuff once set is like hard plastic... i gots to show you's a sample one day... u'll know what i mean....even tested with a blow torch... flame proof too.... DOES NOT BURN!!! after about 30 sec of blasting with a torch... the stuff just sizzles away (slowly) producing a black smoke....but does not burn...

Comes in different densities too... with different expansion rates...

i have to admit i went a lil overboad... but i'd definately put it in all the cavities in the cross members and chassis rail.... The chassis is now like ROCK!! i've heard of chassis torsional stiffness increases in the order of 1-300% !!!!! http://www.ae86drivingclub.com.au/forums/emoticons/ohmy.gif

Although this sounds crazy...but its not that hard to beleive when u really think about it... thats what they are using to build boats these days... Sandwich fibreglass with foam inside... this shit is STRONG!!! and 1/3 of the weight of fibre glass of the same stiffness... What i've got now is Steel/foam sandwich...

I cant be bothered to explain why atm...but i might post up the "science" behind this if yous what... its got to do with transferr of energy from bending to compression...

samuel
12th May 2005, 12:33 AM
Thats a pretty interesting idea you have there, I would be interested to know how much it has increased your total weight now, but still - well worth it in the long run if it does what you say.

Medwin_3sGTE_AE86
12th May 2005, 12:35 AM
i highly doubt u can use expanding foam in ur situation... u'll need to make a mold for that area to contain the expanding foam... plus... the foam is strong in compression... not for much else... if theres heaps of movement i reckon the foam will eventually crack up...

RobertoX
12th May 2005, 12:49 AM
whose hungry for a foam sandwich?

it is something that requires a LOT of research as it can be easily stuffed up!

Medwin_3sGTE_AE86
12th May 2005, 02:16 AM
One set chemicals came in 2 parts... 5 kgs each... i used about 2 sets... that would be 20kgs i guess... if i only used it in the areas i said b4... one set would be more than enough...
The chemicals are exothermic... and do not require oxygen or any other gases in the atmosphere to activate.... there fore the end product should weigh less than the original 2 ingredients.... by how much.... no idea....

DRFT - 86
12th May 2005, 03:56 PM
Ooops double post...

DRFT - 86
12th May 2005, 03:56 PM
cheers everyone.......think it will be silicon or mustik until I do an engine swap and take the loom out.

on the topic of expanding foam though....Ive heard of people using it before for chasis stiffening............was pretty keen on the idea myself.

""Funkdoc""

It seems you used something other than the pressure packs to do this job.... what exactly did u use as I dont know much about this stuff.
you mention that it came in two parts ect..........can u list the cost of this shit and where to get it ect.

thanx.

Medwin_3sGTE_AE86
12th May 2005, 06:21 PM
Here's a site i just found which give a lil info on the product i'm talking about...

http://www.marinefoam.com/polyurethanefoam.html

i'm not sure what u meant by pressure packs but basicall u just mix the two parts together the the chemical reaction will start creating the foam and expand many times its original size... the one i used expands roughly 20 times its original volume.

So to use it... seal off the area completely.... leaving a hole on the top of the area to be foamed... the foam will expand through every lil gap it can find. Pour the already mixed chemicals into the hole and wait a few minutes and the foam will start to expand.... looks pretty cool... The hole up the top is also used to releive the pressure buildup... it is possible to bust the chassis if u do not let the excess pressure excape somehow...

ae86levint
12th May 2005, 08:12 PM
u can get the expanding foam in pressure pasks at any hardware store, builders used to to use it to fill the gap un der and support baths until they realised it eventually compressed and fell away from them, so maybe thats not the best one to use http://www.ae86drivingclub.com.au/dcimages/7/5/4/536981.jpg

DRFT - 86
12th May 2005, 09:47 PM
.........yep.....^^^.......thats what I meant by pressure packs.

thanx 4 that link 2.... I think I will prob do this mod eventually....

How much did it cost and where did u get it... (as site was u.s)

funkymonkey
13th May 2005, 02:28 AM
the expanding foam you buy in hardware shops will collect water with years. When we do mechanic reports of AE86's and older drift cars in japan, we found that some guys had used this stuff in the chassis of their cars and it had collected water and started to rust from the inside... not a good look.

DRFT - 86
13th May 2005, 10:54 AM
Hmmm, doesnt sound good at all........ thanx for the info.

funkymonkey
13th May 2005, 11:55 AM
its usually due to condensation, but mostly because its a sponge like material. Proper marine grade polyeurathane foam on the other hand (which you can't buy in a can) dosen't suffer from this as much, however there is still condensation inbetween the spaces.

Medwin_3sGTE_AE86
14th May 2005, 05:26 PM
Yeah....the stuff that comes in a can is no good.... gotta get the proper stuff.... the condensation is a problem so u gotta get a good rust protection b4 hand.... also it helps to seal off the whole area.... mine's bogged then painted over.... it should be pretty good.....but only time will tell.... lookin good so far....

funkymonkey
15th May 2005, 03:16 PM
bog can soak up water after a while too http://www.ae86drivingclub.com.au/forums/emoticons/biggrin.gif hence why it's only used for superficial repairs in thin layers.

Medwin_3sGTE_AE86
16th May 2005, 05:26 AM
The interior of my car doesn't sit in water dude....

funkymonkey
16th May 2005, 03:44 PM
oh yeah...paint. heh. my bad.

JohnO
16th May 2005, 04:42 PM
intresting stuff

ae86
4th June 2005, 11:16 PM
I dont know much about expanding foam but (funkdoc.) when you say it sets exothermically i understand how it works, fibreglass cures exactly the same way.. so its a 2 part process? ( as in, you use some kind of catalyst?)

The only problem i could see with it would be if you use a fair amount of it, wouldnt it crack? I dont mean after its cured, but with fibreglass, and the exothermic effect, if it heats up too much (if its a large amount) it cracks.. cracks, smokes and will burn the shit out of you if you try to touch it when its at that stage...

And if the foam has heaps of little bubbles in it which could soak up water, could you use some kind of silicone to seal the edges of it?

Hyuga
26th June 2005, 01:32 PM
hey got a pic about filling expading foam into chasis..
I was thinking to do this and remove the sound deadening to my car, so that I can keep the weight down and chasis become stiffer plus I can still listen music as these things good for block the noise out inside the car. I was interested in doing this to my car but if it collects water and cause my car rust then that's no point doing so. http://www.ae86drivingclub.com.au/forums/emoticons/sad.gif

mumblezzz
26th June 2005, 10:19 PM
The stuff that comes in a can will collect water and doesent dry that stiff either. You need to buy the proper marine grade shit that comes in two parts and dries rock solid and waterproof. I can't remeber what the stuffs called but have a look around on club4ag in the tech section. I think it has a write up on whats involved.