Quick and Easy Sound Deadener Removal - A Pictorial Guide

[takai]

Alright, just helped to remove the sound deadening yesterday from Steve-AE86s car. Thought it might make a good tutorial, especially as the way we did it was a whole lot easier than the way i did mine.

Materials
Dry Ice (Get from bait shop) [Liquid Nitrogen would do too ]
Hammer
Prybars
Screwdriver (flat)

Method
*WARNING* Do not touch dry ice with your bare hands, it is extremely cold and can burn
The dry ice you get will normally be in a brick form. Crush it into pebble sized pieces and spread across the sound deadener in each "section". We started with the passenger footwell and then drivers footwell etc etc.


Now, after a minute or two you should start hearing a cracking noise coming from the floor pan. Let it keep doign this for a little while and then hit the floorpan with a hammer. You have to do it quite firmly but preferably not hard enough to dent the floorpan.


Then get your screwdriver/prybar and start levering under the sound deadening. It should come off in huge chunks rather than little pieces. This is due to it being extremely cold and the shock impact from the hammer breaks the surface adhesion to the floorpan. Normally when you start prying the pieces off you move the dry ice to the next section of floorpan and repeat the process.
Depending on how much dry ice you have it is often easier to have two or three people working on it at the same time, because that way you can make the most of the dry ice before it evaporates.
Before long you will be left with this:


Not bad work for $15 worth of dry ice and about 20mins. If i was to do it again i would probably get an extra brick of dry ice just to get everything off.

Good luck people.

*Disclaimer* I, or Toymods, take no responsibility for any mishaps which may happen when you do this to your own car, or any injuries caused by following these instructions.

[45aken]

how much weight do you think you got out?

[mic*]

That looks like as much fun as using hydrocarbon and cleaning black goo off yourself for the next week.

Who's idea was this? Quite clever.

[takai]

Ive seen it done at a few places around the place. As has Steve.

[MR 1JZ]

this is some good info right here people...sure beats the hell out of the 2 days with a hammer and chisel it took me

[mic*]

Hydrocarbon is real messy but i still think id take that over two days with a hammer and chisel

Dats jus bloody carazy.

Dry ice is the way to go twould appear.

Or liquid nitrogen

[sanchez]

wouldn't putting something like liquid nitrogen on metal cause it to become brittle? The dry ice idea sounds good but due to how cold it is, wouldn't it cause the floorpan to fatique?

[mic*]

Yes in a realy minor way that will only remotely possibly be a risk if you smash the pan while it was uber cold.

Metals (and anything) become brittle when cold because at zero degrees kelvin (-273? deg C) the electrons theoretically stop moving.

In metallic bonding, the valance (outer) electrons swim around the positively charged protons.

In a very basic sense as long as the protons stay fixed (they will begin to move with near melting point) the more electrons there are, and the faster they move around, the stronger the metal is.

Once it reaches room temp again after freezing the electrons are buzzing and the metal is more or less original strength.

[Youngy]

This was discussed on CLUB4AG a while back. I still feel that a heat gun on fairly high and a mild plastic scraper (does not scuff the metal at all like a chisel, hammer etc) is the go.

Now before you all flame me. I will say that I did my own car, part with dry ice as Takai as shown and the other part with a heat gun.

I vote heat gun.

[mic*]

...Heat gun sounds even messier than using hydrocarbon.

Scrape a bit up to start. Splash a bit of shellite underneath where the SD is stuck to the pan. It melts the stuff pretty quick. You can even just keep dipping your scraper if its not hardcore stuff. Once you do a lil bit its *reasonably* easy to just dissolve the join without turning the whole lot to gunk.

[45aken]

what's so bad about the dry ice method? i very highly doubt you'd crack the floorpan, it's only -78 degrees, and unless you left it there for 30mins or so, the steel would get nowhere near that cold. i just used a chisel and a hammer, it's only a sprinter. but the dry ice method would have been a whole lot cleaner and better.

[takai]

Yeah, the chisel and hammer method took me about 4-5 days to do, if not more. Wheras the dry ice took about 30mins to get 99% of the car done.

[oldcorollas]

Yes in a realy minor way that will only remotely possibly be a risk if you smash the pan while it was uber cold.
Metals (and anything) become brittle when cold because at zero degrees kelvin (-273? deg C) the electrons theoretically stop moving.
In metallic bonding, the valance (outer) electrons swim around the positively charged protons.
In a very basic sense as long as the protons stay fixed (they will begin to move with near melting point) the more electrons there are, and the faster they move around, the stronger the metal is.
Once it reaches room temp again after freezing the electrons are buzzing and the metal is more or less original strength.

ahh. you are missing the point.
no-one has EVER gotten to zero kelvin... in fact the act of just measuring it adds energy to the system....
so no-one knows what happens at that temperature.

NOT ALL METALS BECOME BRITTLE WHEN COLD

in fact it is only metal with a body centre cubic structure (BCC) that become brittle at their "ductile to brittle transformation temperature" this varies from metal to metal, and varies with the composition and grain structure of a given metal...

titanic failed due to the transition temperature being too high, ie above the environmental conditions, and thus breaking easily instead of being iceberg proof.... same happened with some famous crappy ship which would snap and sink whilst sitting in harbour.

metals like aluminium (and others with face-centred cubic (FCC) or hexagonal close packed (HCP)) do NOT have a ductile to brittle transformation temperature... they are still ductile, but the ductility is reduced.

it IS possible for the metal to become brittle at dry-ice temp.
however, since the metal is also exposed to air and it has high heat conduction (esp compared to the sound deadener which is in contact with te dry ice) it will not get to that low a temp... and not so likely to reach the transition temperature.


the protons begin to move around at low temps? really?

usually in metals you consider it as discrete atoms (that you can just see with high-res TEM or AFM), but the electrons are shared around.
the metal atoms are actually fairly free to move around, and there is always some amount of internal diffusion of both atoms and vacancies in a metal

more electrons and faster moving = stronger? i believe this is incorrect. and are we talking absolute strength or specific strength? pure metal or?

most pure metals are actually very weak. take copper for example... super soft when pure but even ppm levels of OXYGEN increase the strength remarkably....

anyway

[MR 1JZ]

thanks for the input Dr metal

i knew you would eventually find your way to this thread and give some input

[45aken]

it IS possible for the metal to become brittle at dry-ice temp.
however, since the metal is also exposed to air and it has high heat conduction (esp compared to the sound deadener which is in contact with te dry ice) it will got get to that low a temp... and not so likely to reach the transition temperature.

which is what i was saying, but just couldn't be bothered getting into the tech side of things because it is removing sound deadening, were not going to the moon or anything!