Sound Deadening Materials

[Michael Fling]

I have been looking at different sound deadening products for the car. Kyle commented that "The close cell Vinyl foams and the Grey Fiber Mats are the best sound deadeners. Like these SUPER SOUND PROOF WITH ADHESIVE from Aircraft Spruce". I wonder if anyone has used this?

Dynamat seems to be the most popular, although Yos has used Second Skin in this area "for no particular reason, other than it's black".

I am going to be putting Reflect- a -Gold on the rear bulkhead and frame-rails- blame YOS!. I noticed on the DEI website that they offer several "Thermal Acoustic Control" materials called BOOM MAT. It looks interesting.

Can you give me some opinions or recommendations?

 

[Michael]

I don't know the actual dimensions of the SLC floor from side chassis to the console, but keep sound deadening and heat barrier thicknesses in mind when you put it on the sides, console and bulkhead. It could crowd your seats. From what I've seen, it looks like there is good room for the seats in the cockpit, but I would at least keep it in mind. I'm building a GTM, and there isn't a lot of room between the side/chassis and the console. So I placed the sound deadener inside the tunnel/console and the body rockers. Closed cell vinyl ranges in thickness from 1/8" to inches. Fiber mat can also be quite thick.
So you're looking at a trade off for space and level of sound deadening.

Dyna-Mat gived you a thin mat 1/8" of sound deadening material that sticks in place. Then the fiber mat or some sort of heat barrier is used along with it.

Second Skin is a spray-on, or hand painted material that works simularly to Dyna-mat, to dampen the transfer of sound through metal panels. You would still need to used a fiber mat type of material to block heat transfer into the cockpit.

People who have used each type have done so with good success. So it's really up to you. Price, and ease of installation is usually the driving factor for most. Dyna-mat can be quite pricey when you compare it to other products that are exactly the same, except that they don't have the dyna-mat logo stamped on them...

Mike

 

[Vidal]

When it comes to reducing the noise floor and quieting the cabin you want to duplicate (with in the limitations of the vehicle) what has been very effective in production autos. This with an emphasis on the higher end and luxury vehicles. This is normally accomplished in three parts or layers. 1) Dampen the panel. 2) Block the noise. 3) Absorb noise and decouple the panel from the sound blocker.

This is accomplished in different ways for different parts of a vehicle. The floor will normally have formed panels with a dampener applied. This is normally followed by the vehicles carpet which contains a sound absorber/decoupler (the carpet's insulation) and a sound blocker (the heavy mass loaded portion above the insulation). Fire walls may follow the dampener with an even thicker insulation to compensate the the engine noise and heat. The roof may or may not have a dampener or a sound absorber/decoupler. If not the headliner panel and the liner material are it.

So our kits where designed to be light and fast and with this comes a loud noise floor. Our Exhaust and engines are inches away from our ears. This makes if extremely difficult if not impossible, in some cases, to get the noise floor down. The three part approach can still be very effective.

1) Dampen the panels. For our kits, adding bends and/or rolls is not practice for most of us, but adding the dampener (mat or liquid) will do an excellent job dampening the aluminum panels. Which is best, mat or liquid? The answer is both. IMO a combination will make for an easier install, but is purely preference. There may be a area where you are unable to properly install mat that you can shoot with the liquid or the reverse. With the panel dampened it will have a greatly reduced tendency to resonate and transfer sound through the panel.

2) Add a sound absorbing/decoupling layer. Automotive carpet insulation is a great sound absorber and decoupler. Foam (closed cell) is another option. This layer decouples or physically separates the panel from the sound block and also absorbs some of the sound that passes through the panel. The separation of the panel and sound blocker is required. If the sound blocker is placed directly next to the panel it will transfer the sound that is passing through the panel instead of blocking it.

3) Add a sound blocker. This can be accomplished in different ways and with different items. A mass loaded vinyl over the insulation/foam, a door panel with a layer of mat applied to the back of it. Dyna Pad which is a combo product of 2 and 3. You can also have great results with only 1 and 2 of the list.

 

[Kyle]

In short... 1) Dynamat 2) Insulation material either closed cell foam or fiber type 3) Vynal & felt backed carpet... All this translates to the reason that quiet luxury cars weigh 4000Lbs.


But that being said a 2800lb SLC that was comfy and quiet would still be a way more capable car then 95% of the members here. Even if you could come close to pushing it to its limits that is so far past common sense and legal smarts.

 

[Vidal]

In short... 1) Dynamat 2) Insulation material either closed cell foam or fiber type 3) Vynal & felt backed carpet... All this translates to the reason that quiet luxury cars weigh 4000Lbs.


But that being said a 2800lb SLC that was comfy and quiet would still be a way more capable car then 95% of the members here. Even if you could come close to pushing it to its limits that is so far past common sense and legal smarts.

Well…yes and no. The auto manufactures will go fairly thick on the mass loaded vinyl and the higher the luxury the thicker. Firewall, behind the back seats, back of door panels and heavy carpet backing.

But for the aftermarket, if you actually weight the materials prior to the install you will see that (for the purpose of lowering the noise floor) you are not adding a serious amount of weight.

Consider that 50sf of aluminum backed 80mill dampener will weigh ~23lbs, 1/8" Mass Loaded Vinyl is ~1lb per sf, and the foam or insulation will be in a range of ounces to a few pounds.

A panel does not require 100% coverage in dampener to lower its resonating frequency. 25% coverage using strips is usually sufficient.

You may want to also consider the primary noise culprit (the exhaust) and focus on it and then firewall in the overall plan to help lower the noise floor.

I believe a good level to shoot for is 65-80dB which is on the top end of conversation level but under the sustained exposure hearing loss level.

 

[Kyle]

You may want to also consider the primary noise culprit (the exhaust) and focus on it and then firewall in the overall plan to help lower the noise floor.

You speak the truth, one of the best ways to have a quiet cab is to not make the car loud in the first place.

 

[Yos]

As usual...Vidal laid it out perfectly.

I plan on using the Dynapad on top of my Dynamat. Then carpet of course. I'll put treatments on both sides of the firewall in hopes that'll help too. I added up my materials, and it came to about 60lbs I think. Not too bad...

The Second Skin and Dynamat are basically identical products. One has a reflective silver finish...the other one is flat black.

 

[Michael Fling]

What point in your build process did you apply your dynamat?

 

[Vidal]

What point in your build process did you apply your dynamat?

You may have been asking this question directly to Yos, and he can definitely be more specific to his process, (if so, just disregard my general comments as you wait out the detailed version) but in general you can apply your dampener very early.

You may want to wait for final installation of the foam/pad/insulation because it can be damaged fairly easily. It’s a good idea to do mock-ups in areas where you may expect the added materials to create a clearance issue.

For instance; you’ve completed some custom fabrication to the floor, mocked-up everything that will be mounted and just pulled it all back out. Now would be good time to apply the dampener.

Areas where it will be increasingly harder to get to, as components you do not intend to remove are installed, will benefit from having the dampener installed as early as possible.

Looking at the SL-C build, it appears that you can add the dampener, to most if not all of the panels you may want to address, very early in the build.

HTHs.

 

[Michael Fling]

Awesome- TY

 

[Yos]

Looking at the SL-C build, it appears that you can add the dampener, to most if not all of the panels you may want to address, very early in the build.

+1 :thumbsup:

Hey Mike...I would suggest mocking up the interior first and drilling the seat and pedal mounting holes. Just remember anything that requires accurate measurements should be done first (Cutting, drilling, etc...) Trying to measure off corners covered in the dampener is a bitch. I screwed up and didn't drill for the seats first. It was a pain marking center lines and such from under the car. Measure first!

Other than that, you're good to go installing the Dynamat. It's easy to cut out of the way for attachment points. I cut small spaces in the material around the bolt holes for washers to fit in. Then I mounted my seat brackets on top of the washers, so when everything is torqued down...I'm not squeezing the tar out of the dampener.

 

[Michael Fling]

Thanks Yos. I was watching video of insulation on the new build thread. I was surprised about the application on the outside of the front bulkhead area. I assume this would be visible when the front bonnet opens?

 

[Howard Jones]

A bit of advice here. But it may be a bit anal. Mount seats and seat belt attachment hardware DIRECTLY to the chassis material. In this case bolts should go through the floor and have a big fat, thick steel washer on both sides contacting the alum floor directly and without any soft material in between.

The forces involved in a medium shunt are very high and loose bolts shear/pull out at a much lower yield point. The carpet material has the same effect as a loose bolt. So does anything else such as noise adsorbent or heat resistant material.

Seat Belt eyes can be mounted as above and a little slit cut into the carpet to allow the carpet to be laid over it with the eye poking through. Seat mounts can be done the same way with a longer slit.

Track day tech inspections will only get more careful as time goes on. These cars are really full on racing prototypes and will get a fairly close scrutiny I would expect. At least they should. We should expect no less from ourselves.

Sorry if I get a little paranoid from time to time but I have seen the effects of some fairly big shunts and you want all you can get from the safety systems.

 

[Michael Fling]

Great info. Thanks. Does anyone have pics of sound dampening / heat reelection materials on bulkheads and side of cockpit?

 

[Yos]

have a big fat, thick steel washer on both sides contacting the alum floor directly and without any soft material in between.

Thanks Howard! That's the process I was trying to describe. I did exactly that...

 

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Errr... Assuming this is a post from someone actually trying to be helpful to those building a car and not someone just looking to market a product, I don't think a cell phone jammer will reduce perceived engine noise at all.

I think you may be confusing a phone jammer with Active Noise Cancellation technology. A noise cancelling headset WILL reduce perceived engine noise (and the resultant resonance with the car's structure), but not every driver wants to wear a headset all the time.

EDITED TO ADD: After reading your other post which is nearly incomprehensible, I conclude you are using Google Translate to shill your phone jammer product here. Go away.

JR

 

[Cam]

Hmm, the thing i like about the SLC is its pretty hard to carry on a conversation with the block 15" behind your ear. Maybe this makes the SLC a vacation from the rat race?

 

[PeteB]

Great info. Thanks. Does anyone have pics of sound dampening / heat reelection materials on bulkheads and side of cockpit?

Here's my bulkhead: Dynomat and EZ-Cool (EZ Cool Automotive Insulation heat barrier and noise reduction for cars, trucks, classic cars, street rods and much more)


Interior with Dynomat:

 

[Pierre-Louis]

If you go with Dynamat, you can consider using Fatmat products, basically same product and half the price...

 

[Cliff Beer]

Personally, I've used dynamat....and just plain old closed cell foam. The basic closed cell foam works just as well in places where there's no thermal control needed, and it's a helluva lot less expensive.

Around tunnel arches and inside rocker panels I'll glue the stuff down with 3M trim adhesive, this seems to work pretty well. For floor areas I don't glue it down to the floor because I like to be able to remove it if moisture gets into the floor area and collects. Instead, I glue it to the back of the floor carpet so the carpet (and foam) can be easily removed for cleaning and drying of the carpet and floor area if necessary.

My approach is low-tech but it seems to work pretty well.

 

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