So what have you guys replaced this stuff with? (sound deadening)

[drunkenmaster]

Thanks Mike, pics are great. I am not sure if I will extend as far onto the floors as you have, I think my paranoia will require me to be able to check the floors for rust every so often but it looks very good, have you had a chance to compare its effectiveness?

[zhead240]

here's what i have.jute, carpet and another peice of carpet. note the holes in the carpet ,i figure from heel of shoe. the other two holes at the end fit onto metal hooks on the floor. also there are two snaps that hold in place on the firewall.

[drunkenmaster]

Mike (and others), what did you use to cut the deadening to shape as well as make holes for metal brackets etc?

Last time I did this on another car I ended up gumming up a pair of scissors and a craft knife with sticky bitumen from the centre of the deadener.

[Mike]

I used a razor blade knife with lots of spare blades! I measured a lot of it with a cloth tape so I could curve my measurements.

[drunkenmaster]

Nice, thanks

[240 in OZ]

I spoke with Scotts Old Auto Rubber in Melbourne yesterday and they sell a black thick mat which sticks to the metal floorpan. It is like applying a sticker, ie peel the backing off and stick it down. It can be cut to size/shape readily and can be moulded with heat application.

However, it cannot be painted over. I was considering it to replicate the original masonite type board but as it cannot be painted, its back to the drawing board.

Maybe it would be useful for your application?

Joseph

[EScanlon]

Quick and Dirty primer on Sound attenuation:

From my days selling Ceiling Tile.

STC: Sound Transmission Coefficient; The quantity of sound TRANSMITTED THROUGH the material itself.

NRC: Noise Reduction Coefficient; The quantity of sound ABSORBED by the material itself.

Although these numbers seem to be the inverse of each other, they aren't although they go hand in hand.

The sheet metal of the Z transmitts sound quite readily, that's the reason they put the "tar paper" on the floor boards. The Tar Paper reduces the metal's ability to resonate harmonically and therefore the amount of sound that it will regenerate on the inside of the cabin from the sound waves received on the outside. Metal is a material with a very low NRC, and normally a very high STC, especially as sheet metal. The tar paper changes the STC by changing the metals ability to vibrate.

Sometimes in addition to the tar paper, they added a fibrous material to reduce the sound that still resonated through the metal. An example of this is the firewall and the transmission tunnel. There they used a fibreglass type mat or "horse-hair" or "jute". This material has a very high NRC, and a very low STC. Additionally it also has very high temperature insulation properties. Your typical house insulation has these qualities as well.

Reducing noise in the Z calls for reducing the metal harmonics that transmit sound INTO the cabin from outside. Typically a tar paper, or bituminous, or "soft" material is adhered to the metal. The key being that it is ADHERED to the metal. This reduces the high frequency vibrations that go through sheet metal very readily. If you then add a layer of high NRC material, such as carpet, insulation, or some other "fluffy" type material (i.e. with lots of air space between the strands) it will help reduce the mid and upper low frequencies.

By placing the STC and increasing the NRC of the various panels of the car, you'll do a good job of reducing the noise. If you target those specific areas which are known noise producers (engine, transmission, rear end) with insulation specifically geared for the sound they generate, you'll really reduce the sound.

My car has the "tar paper" all the way from the cowl bucket, down accross the firewall from side to side, across the floor pans and the transmission tunnel all the way to the tail-light area. The only part of the "floor" that isn't covered, is the tool box lids and the spare tire well. The insides of the tool boxes are covered as well as the bottom of the particle board spare tire cover. Additionally, I added some inside the doors themselves and the inner rear fenders (inside of the outside metal), the inner metal of the hatch and the rocker panels and doglegs under the quarter windows.

The firewall and the transmission tunnel are the only areas where I used a fibrous insulation, and that was the original "jute" insulation. However, if I had to replace it, I would opt for a high temp insulation similar to what gets used in insulating stoves. This tends to be stiffer and denser than standard house insulation. This makes it easier to cut and to glue in place.

I've had various people ride in my car and they all comment as to how quiet it is. I can listen to the original radio with mono sound and not need an amplifier. Additionally, my wife and I can converse with or without the windows being open.

For What It's Worth

Enrique

[240 in OZ]

Nice post (as is usual). So where does one buy "tar paper" and what does it look like when installed?

Thanks

Joseph

[Zedrally]

Nice post (as is usual). So where does one buy "tar paper" and what does it look like when installed?

Thanks

Joseph

I haven't seen it for sale in Aus for 40 years!

When it was available, you could buy it from a hardware.

Don't bother with Bunnings, however you could try a very old established country store.

[one never knows what turns up in these stores]!

MOM

[EScanlon]

"Tar Paper" is a catch-all term for a soft substance in a "sheet" form with adhesive on one side. The other side may have a film, aluminum, plastic, felt, foam, or ???.

Dynamat, Brown Bread, B-Quiet, and Q-Pads are just a few of the product names that I know of that are basically the same thing. Differences between them will (usually) consist of claims of durability, sound attenuation and .... In my experience, while there are a few differences (some have perforated aluminum foil, some have smooth, some have clear film, others have felt, or vinyl, or ...) for the most part what they are is a sticky substance that does not harden that can be applied to the sheet metal. The most common of these substances is plain old tar that has been pressed into sheets or rolls, and adhesive applied on one side, hence the term "tar paper".

Tar paper is seen as more desireable than another product called Body Shutz. Body Shutz is another name for undercoating, which to some people is like saying poison. However, properly applied on properly prepared metal it actually does wonders for reducing sound, rust and wear on the underside of the car. Body Shutz is basically liquified tar in a liquid base that you "spray" onto the underside of the car. I wouldn't recommend shooting this on the inside of the vehicle as the liquid base (I believe it's mineral spirits) takes WEEKS to evaporate and will nauseate you.

Check with your local Automotive Paint and Weatherstrip store. They should have something although the name may differ.

Hope this helps

Enrique

[1 Bravo 6]

Check out the add by Tru-Fit Carpets in the Just Cars Magazine.

The advert reads;

Under Bonnet Noise Absorption Pads;

Comes pre glued. Trim to size. Easily moulds to irregular shapes. $49.00 plus freight. Size = 1000 x 1500mm.

Bitumen/Felt Underlay;

Far superior noise reductionqualities than ordinary felts. Consists of a high density bitumen barrier sandwiched between 2 felt noise absorption layers.

$42.00 plus freight. Size = 1000 x 1500mm.

Firewall Heat and Noise Insulation - Engine Side;

Aluminium outer. Bonded to sound barrier/absorber. Stops heat and noise before it can enter cabin. $49.00 plus freight. Size = 900 x 1500mm.

They also have;

Felt Underlay;

Our standard noise reducing under felt as used by most Australian car manufacturers. Won't rot when wet and is more effective than ordinary jute felts. Front and Rear $27.00 plus freight. Front only $15.00 plus freight.

Might be just what you're looking for.

Rick.

[Z Kid]

Here in SA you can still get the tar paper stuff from a motor trimmers, there was a bit of a sheet left over here from when dad did the tail of his E type. It was about 20 bucks per square I think, but had to be bought in semi bulk.