Sound Deading Material

[Ron Earp]

I have had verbal discussions with Bob and Hershal on putting sound deading material into the GT40. I think everyone agrees it would improve the car quite a bit. I will try and sandwich some anywhere in the car I can where it will not cause moisture or service problems. Certainly underneath all the carpets and leather.

What is the best stuff around to use? DynaMat (spelling) is one I know of that I have used in the past. But, there may be newer products that are superior. I don't know much about the street rod scene, those folks have probably already figured all this out.

Any comments from those driving 40s? I'm striving for a very sophisticated end product where motor noise is present but wind and road noise is largely muted. I think it possible, it will just take some doing.

Ron

 

[Bill D]

Hi Ron

There is a company in Oxnard, CA that sells insulating material for cars, both original and replica. It was listed in one of my issues of Kit Car. They have a website, and I will locate the information tonight and post it tomorrow.

Having as many sources as possible for anything required to build this car is advantageous.

Bill D
Los Angeles, CA

 

[Hershal Byrd]

I have thought about this as well. I have spent many hours in the body shop looking at the way new cars are insulated for sound. The Japanese seem to have the best handle on doing this along with the germans. While looking at these cars I learned that they consentrate on the passenger compartment. Most all the panels around this area is sprayed on the backside with a rubbery black substance . Sometimes it's a tan color. It's not sprayed on very thick,just enought to cover the panel. What I found this does is that sound from outside will hit the soft rubbery substance and it absorbs it or defracts it . The only way to describe it is like an iron bell being rung and then spray the bells inside with this and then try and ring it. It will hardly have a noise. I guess what these manufacturers are doing is making all the surfaces soft side to deflect the sound. Along with the right carpet and pad/insulation this should keep any passenger compartment low decibal.

Hersh

 

[Guest]

Ron, where it was visible, I used Dynamat Extreme (has aluminum layer) under the carpet areas, etc, I used High Temp Mastic and a layer of flame retardant polystyrene foam. These two layers cost around 1/2 the price of the dynamat. If you want the ultimate, get the sprayed on polyurethane coatings (used as bedliner coating). There is a outfit in the shopping center on Hwy 70 (where NeoChina is) that is supposed to be the best according to the local competetive audiophiles. DEI also makes a price competitive product to Dynamat, if you can find anyone to get it for you.

 

[Ron Earp]

Hershal,

I agree with you. I've recently taken apart our Audi to install a mobile hands-free cell phone and its' sound deading is different from the average American sedan. They do have a sprayed on coating on the outside of the metal and at joints and also use some material like Dynamat.

Most American makes use nothing directly on the metal and instead pack a paper-backed fiber on firewalls, carpet, and whatnot to deaden sound. Doesn't work as well. Plus, it probably weighs more. But it is cheap.

POR-15, is that the ERA stuff?

Lynn, is POR-15 similar to the stuff you used? When you driving that GT40 down to Apex? I need a ride in one. Sorry I wasn't around the other week when you called but it WAS a Friday and SOME of us poor suckers have to work those days.

Ron

 

I cant speak for other kits but those building roaring forties should think twice on sound deadening mine is fully upholsted with not too much padding material under the carpet and the sills . the sound of the engine which is 320hp with 8 barrel injection is just glorious with a terrific wet slurping sucking sound when floored . gee i'm getting excited sitting here in the office just thinking about it. regards

 

Hi Ron
I used 1/2" MDF inside the engine fire wall coated in silver foil then I used Sikerflex to glue the panels into place. this was hidden behind the alloy skin. I
used a carpet with thick felt backing.
The MDF in the rear fire wall stops heat as well as sound. These cars can get hot in the cockpit! but my car is cool no air con required.

Chris Melia

 

[Rick Muck- Mark IV]

For a "Euro" type sound deadner, try Wurth (should be an umlaut (sp) over the U but not on my keyboard configue). Check with local body shops and import dealers. They sell a vey good plasticized spray on deadner. Available in rattle cans or bulk for use with a Shutz gun, the plus side is it can be painted over and is vey durable. We have used it under fenders as it is chip resistant and will stop stone pecking as well as sound. Do not over do it and get it way too thick as this reduces its' adheasion. This is the product that Audi, Benz and all the other Nazi cars use. All of the Wurth products that are imported are vey good. They also have a very nice NON-silicone interior vinyl cleaner and a great product for cleaning rubber, i.e. tires and weatherstrips, without looking like an Armor-All tanker was dumped on them. And, no, I don't work for them or have any interest in them!

Rick

 

[Guest]

Ron, that was the first day I hadn't put in 10-18hrs (weekday) in about a month and a half. Still working the big deal with Cisco.

As to POR-15, I had never heard of it until Mike mentioned it. My understanding is that it is more of a undercoat/rust killer-preventitive than a sound dampner. Think twice about the spray on Dynamat! Other than very small areas that you just can't apply mat to, I have heard nothing but complaints about it and it is stupidly expensive when you see how much coverage you get from a can. For my firewall, I have the silicone fibre/aluminized ($$)in front of and over the engine. On the periphery, I used the cheaper aluminized ticking type heat/sound shield. On the cabin side, I used the high temp mastic (McMaster-Carr)/polystyrene and carpet. I did the entire horizontal underside of the rear clip the same way as the engine side of the firewall. The vertical sections are covered with high temp w/ceramic aluminized paint. Underside of the front clip and rear wheel wells I sprayed with Featherfill (spayable bondo) because they were sooo rough and then several coats of 3M Underseal. If you want a rubberized self applied undercoat, this is what to use. If you do though, cut about an inch of the spray tube and use it in the nozzle. Otherwise, the edge of the spray pattern catches the edge of the can and makes a mess. They give you two nozzles, but keep them all in a can cap with lacquer thinner (sp) because they will clog. Sounds like a pain (and it is) but the results are worth the effort! If you mess up or drip a big blob of it, pat it out with a rag (don't wipe) and respray when dry will hide it great.

The absolute ultimate would be to take the car to Line-X there on 70 and have them spray all the underside and inner walls. This will dampen and strengthen the entire car. If I had the extra $$ that is what I would have done. They have been recommended by several independant sources.

I found a forum for car audio on the net that was a great source of information on this subject if you want to research it. These guys have competitions with their car audio systems and are REALLY into it.

 

[Guest]

I just read the post about Wurth. This is what John uses rather than the 3M stuff and I concur with the statements of Rick. I would have used this in the wells if I hadn't already started with 3M when I found out about it. This is also used on the lower panels on the exterior. I am sure you have seen the kind of bumpy lower panels on some Porsches and others - Wurth.

 

[Guest]

I have a Wurth catalog and the eastcoast reps bus card. I will dig it out and forward it to you.