Sound Deadening "Quite Coat"

[DG624]

In January several owners posted about using a sound deadener. I contacted them about results but also would be interested in other stories about this stuff or similar material as a subsitiute for Dynamat.

I would like reduced weight and less noise. The makers claim that they are better than Dynamat. Stuff seems easier to use (paint on) and lighter 8lbs a Ga. Even water soluable and non-toxic. Who has long term experience?

[Grady Clay]

DG624,

What other maker(s) and links? What is "Quiet Coat?"
What link to Dynamat?
What prior posts?

This is an important issue, particularly for lightweights that want some sound deadening.

Best,
Grady

[DG624]

There is a topic called "sound deadening, again" 10/4/03. There they mentioned Quiet Coat. There is another product called Noise Killer similar stuff. Both are brush/spray on material designed to reduce noise with less weight. Since this is alot of work I wanted to be sure of the results. You can contact Quiet CoatQuiet Solution, Inc. Application

"QuietCoat 118 excels at deadening sound for steel, aluminum, plastics, composites and other non-porous materials. It is new high technology viscoelastic polymer coating to make any material quiet. Excellent for removing (absorbing) unwanted noise and vibration in metal, HVAC
systems, motors, engines, gears, etc. QuietCoat 118 is a water-based, non-toxic, no-VOC product that will not burn."

"QuietCoat 118 converts the kinetic (noise) energy into heat energy. You can theoretically measure that energy conversion, but it’s less than 0.1° Fahrenheit. By absorbing vibration, noise can be reduced by up to 20dB – a remarkable 75% of the perceived noise, depending on
application."

"QuietCoat 118 is easily applied on any surface by brush, roller, or sprayed on with a spray gun using an air compressor or airless paint sprayer. The more coats you apply and the thicker you apply it, the more noise will be reduced."
Surface Preparation: QuietCoat 118 adheres best to dry, clean surfaces. All grease, oil, lubricants, waxes, polishes or other material must be removed with water by pressure washing.
A simple household cleaner like Formula 409 will remove most oils and grease. Paint does not need to be removed but it must be clean. Loose dirt, rust or other debris can often be removed by pressure washing (power wash). If the cleaning process exposes bare metal, the metal
should be primed for best adhesion. The surface must be dry before applying QuietCoat 118.

This is their site:
http://www.quietsolution.com/passenger_vehicles.html

[turbo6bar]

I am in the midst of a QuietCar project in my 78SC. I planned to write a report in a week or so, but I can put up some thoughts now

1) The stock padding and heat shiedling in the rear seating area (from B-pillar to rear window) weighs 21 lbs on my shipping scale. This was the padding alone and no carpet, panels, or rear deck.

2) I have applied just over 1 gallon of Quietcar to the metal (after removing the glue). I test drove the car after applying 1/2 gallon, and the noise was terrible.

3) I feel one gallon of Quietcar applied judiciously will equal the stock sound deadening.

4) Upon test driving the car for only a few minutes, the heat coming through the firewall was appreciable (warm to touch, guessing 100-110 degrees F). My plan is to use a radiant heat barrier on the engine side of the firewall.

5) I found an aviation company that sells a high tech firewall mat. It is a combination heat barrier and sound deadener. They claim a 3-4 db reduction in sound + great heat rejection properties, but the padding only weighs 8-9 lbs in a typical aircraft application. I emailed them for info, but no response. This might be a great product, IF the cost isn't astronomical.

My goal in this project was improved sound suppression with an appreciable noise reduction. I need more time, but so far I think I have succeeded. This project should yield a 5+ lb weight reduction and far less noise. Subtract rear seats and rear deck+speakers, and you can subtract yet another 26 pounds of weight.

One of my future projects is lexan side and rear windows, with the overall goal of reducing weight without sacrificing driveability.

[turbo6bar]

A 50% reduction in sound is equal to 3 db, so the aircraft firewall acoustic blanket would work well.

I agree with you about the noise on long trips.

Give me a couple weeks, and I can report on my results. I haven't decided what carpet kit to use, yet. Jurgen

[Zeke]

A material simsilar to what you describe here is used on the bottom of better stainless steel kitchen sinks to eliminate the tinny sound. It works well in that application. As such, the Quiet Coat would be suitable between you and the road keeping water and rock noise to a minimum. In other words, noise caused by direct contact.

Where you need sound and heat insulation, my opinon is that you should use pad type insulation. Pad insulation is good for capturing sound waves being transmitted though the firewall. It doesn't matter much whether it is attached to the transmitting source or not.

I get my info from a study of noise transmission in houses which I deal with in the window business. We design specific windows for specific noise frequencies. A home near a freeway gets a different window than a home near an airport, or school yard, etc.

One rule: Air gaps let noise through. At least the Quiet Coat would be good at that.

[Eric Coffey]

Hmmm, I've used stuff called "Sound Coat" (or maybe it's "Soundcoat"), on interior surfaces of (home) loudspeakers, and it works excellent. It had the consistancy of whipped butter, and you used latex house paint as "thinner". If it is anything like it, you will be pleased.

[RoninLB]

The engine hatch in a boat may use lead. It works great.

[Yankee911]

I'm building an RS lightweight from a 72 T. Where do you get this stuff?

[Evans, Marv]

To comment on Milt's comment about pad insulation. I used some I got from the Whitney catalog. It came in a sheet about 3 X 6, if I remember right. About an inch thick, with an aluminum mylar side and a thin layer of lead in the center. I used it on my 912, but couldn't tell definitively if it cut down on noise, since I did it right after I bought the car 12 years ago. It was really easy to cut with an electric knife in the pattern of the old firewall sound pad. I glued it on with the mylar side facing the engine. It stayed on until just before I sold the car a few months ago.

[Randy Webb]

IF you add Webb to your seaches, you'll get my take on this & I also think I posted an Email from one company's president.

For spray/stick-on coatings there are two choices: things that work by adding a wt. to a panel (this alters the resonant frequency -- like a drum head) and micro-encapsulated beads which turn the sound energy into heat energy (not enought to measure, oK?). Original Dynamat is an example of the former and the Quiet Coat is an example of the latter.

I have not run any tests on these things! Testing would be non-trivial.

Another trick is to take the stick-on pads you get and cut them into strips -- then use the strips with spaces in between instead of a full pad. This can cut the wt. penalty by 1/2 to 2/3 w/o really altering the noise reduction much.

I did my doors that way and used a QC spray product in and below my tranny tunnel - using an idea from Ron in LB. I had the painter who redid my engine comp. spray some clear over the QC underneath the trans. to protect it from water and abrasion.
This makes sense to me, but i have not tested it even subjectively (still trying to get the modified trans mount and engine wiring done).

I think the ideas of looking at home soundproofing and hanging around airports are good ones. I have not tackled my interior firewall surface yet but plan to do that w/in a year. Be sure to find out the wt.s of anything you use and evaluate the frequency dependance of the sound reduction -- that does make a difference. It might be wise to look at what PAG is using nowadays. It would be esp. interesting to tear apart that guys C-GT that got rear-ended....

Remember tire nose and wind noise are real problems even today, and the 911 -- even when new -- got all sorts of wind noise complaints.

Have fun. Anyone that has new info can report back and the magic of the flying Pelican will capture it all....

[RoninLB]

Originally posted by Grady Clay

What prior posts?

This is an important issue, particularly for lightweights that want some sound deadening.

this topic has been discussed a few times. Noise is fatigue. and although somewhat different, harmonics also create driver fatigue. Sheepskin covers in aircraft reduce transmitted harmonics as much as 40%. Randy has the best hard info around here. although the issue of sympathetic harmonics has never been discussed it's dealt with thru getting the biggest bang for the added weight in key areas.

[Randy Webb]

Grady - search on some terms sound + deadener + webb or use deadening

I think Ron means noise will cause fatigue of the driver.

[DG624]

The Quiet Solutions site has a comparison of different noise levels and how a 15db reductions affect conversation. They suggest two coats at 1mm each or a gallon for 20 sq ft which equals 8 lbs. Not too heavy for a reduction in noise levels. They show a new 996 in their pictures but I don't know if Porsche uses this product. That would be a good question for anyone what does the factory use on their new cars?

[Grady Clay]

Randy,

Thanks, I had looked at a few of the 331 posts containing sound + deadening. I just looked at your original post. Good stuff.
My ’68 has no sound deadening at all in the roof or doors, that started in ’71, I think. Of course it has the “tar” on the pan and the pad at the firewall. It is a “tin can” in the rain but weighs 2220 # with a full tank and spare.

There is some really good info on the Quiet Solution site listed above.
One thing I didn’t see is its ease (or lack thereof) of removal.

Some things for us all to remember:
A 6db reduction is half, 12db is one quarter – it is logarithmic.
The sound transmission from the surface to the air is highly dependent on the type of surface.
Sound energy is conducted through solids (metal) much more than through air.
This “viscoelastic” term means some of the sound energy is turned into heat.
Higher frequencies are usually easier to attenuate than low frequency.


Milt is right on. We also need to reduce the heat transmission into the cockpit.
Thermal insulation is not the same as sound insulation.
The three modes of thermal transmission need to be addressed – Conduction, radiation, and convection.


One of the seat-of-the-pants things I have learned is that layers of differing characteristics work best. Different density, thickness, viscoelasticity, thermal conductivity, angles, texture, and more.

Marv’s lead centered pad got me thinking. I wonder how well multi layers of 1 mm QuietCoat 118 and say 5 mm styrene bead board would do? With the QuietCoat being water base it shouldn’t dissolve the styrene. The top layer have silver Mylar. Black Nomex draped (not glued) over the assembly. Sorta RS without the noise and heat yet still lightweight.

Best,
Grady

[DG624]

Grady, Dynamat makes something called hoodliner that absorbs noise and reflects heat.

The Hoodliner's "Sound Soaker" foam absorbs engine noise, delivering a quieter listening environment in your vehicle. In addition, the Hoodliner's 1 mil. reinforced aluminized skin creates a water/oil barrier that reflects up to 97% of radiant heat to protect the hood's paint finish.

This stuff sounds like it could replace the pad that fits around the engine compartment at the fire wall. Another thing using hot ceramic coating may also reduce underhood temperatures for the muffler and headers.

[turbo6bar]

Quick update: I have roughly 10 lbs. of Quietcoat on the rear seat, rear deck, and interior wheelwells. I was originally very disappointed in the noise. Well, the interior is bare (no interior, rear seats, or seat belts). The noise was coming through the inner seat belt mounts (through holes directly to transmission area). Also, there are approximately 8 stamped oval-shaped holes in the rear deck. More noise was coming from this area. After covering the holes with masking tape (temporary measure), the noise levels decreased immensely.

Also, there's significant noise coming from the transmission hump area, and the panel directly behind the rear seat backs. It would be smart to add more material in these areas, and use less Quietcoat near the inner wheelwells. Also, the coverplate for the shift coupler is another noise source. Did you know there's a 1/4" x 6" air gap near the coverplate? It is normally filled with carpet, but it's a gap nevertheless. Yet another noise source is at the joint of the rear deck and the headliner. I haven't figured out how to attack this noise source.

I honestly believe attacking the noise sources will reduce noise immensely, even in a stock 911. Until all air gaps are eliminated, I cannot fully evaluate the performance of Quiet Coat. However, I have high expectations.
Jürgen

[Randy Webb]

Jurgen - waht year is your car?

Today's light wt. tidbit: Boxster floor mats are significantly lighter than the floormats used in my 1975 911S....

[DG624]

Jurgen,

What do you mean by the rear deck? The area behind the seats or the fire wall? Have you tried to replace the pad behind the engine? I have a source Dynamat as described that may be better than stock pad. I don't know about the gap at the transmission tunnel. I didn't see a gap after removing my cover. The noise level went up without the cover but not terrible.

I think you are right about first finding all of the gaps and then working on the general noise level. Then you don't need as much Quiet Coat. With reduced noise the car would be much easier to drive lond distances.

DG

[turbo6bar]

My car is a 78 SC Euro model. When I refer to rear deck, it's the panel directly below the rear window. You commonly find speakers in this panel. I haven't replaced the engine pad. I will pull the engine and transmission and do the work from the underside at that time.

I'll take some pictures of the gap by the shift coupler cover.

Jurgen