This is me, picking up my freshly repainted 914 from PMB Performance.

Click to view attachment

Now that it's home, it's time to start putting things back together.

I'm looking for sound deadening solutions for the floor and interior back panel. I'm planning on keeping the interior back panel, but figured this would be a good time to enhance it with some sound deadening capability.

My searches haven't been very successful. I'd appreciate it you guys could offer some advice or point me to previous threads on the subject.

I have a roll of Dynamat for my car when it comes together. If I recall it is about 1/8" thick of a semi-sticky black tar-like substance with a heavy foil backing. No odor no glue required. Just cut and using a smallish roller lay it out and roll it nice and smooth and flat. I like to color and the paint job looks to be top drawer.

I've used Dynamat in several cars; most recently my 914 and '61 TBird resto. A little pricey, but good stuff.

George

I've used FatMat on several cars over the years with terrific results. It's virtually the same as Dynamat Extreme without the high price.

I have these two options on my list.

Sound deadener (Heavy)
50 Sq Ft Noico Self-adhesive Foil & Butyl Mat 50 Mil (Same basic product as Dynomat, however much cheaper and in easily workable squares) NOTE: They do sell this in 80 mil, but state that the 50mil is the best weight to results.
http://www.amazon.com/gp/product/B00URR4O5..._dp_o_pC_nS_ttl


Heat/sound barrier (Light)
EZ Cool Automotive Insulation
http://www.lobucrod.com/



Basically i'll use the Sound deadener sparingly on large flat panels and over gaps to help deaden the tinny noises. I will cut small strips and place them on every piece of metal to make it more "heavy". From there I will use the heat/sound barrier (lightweight) over that and create a full barrier as this will be my total seal, doubled up at the engine firewall.

Looks very nice Ernie.

Eric & Gene did a wonderful job on the car. Here it is after I got it home to Flagstaff.

Click to view attachment

+1 on the FatMat. A lot cheaper than DynaMat and just as good.

I used a 50sq ft roll of 80mil on my 914. Made a big difference .


Bob

I bought FatMat a few years back, cheaper than Dynamat.

Another vote here for Fatmat.

Lots of good info here and online.

My two cents.
Sound deadening is about stopping both sound waves and vibration.

Certain materials stop certain sound waves.
Product like dynamat at rubber-foil which blocks two types of sound waves.
It also builds up the thickness of the metal to reduce vibration.

I would suggest a multi prongs approach.
Ceramic spray on sound deadened on the engine bay side.( lizard skin is on product)
1/2 inch foil faced mat on the engine bay side (914 rubber has that)
Dynamat on the inside.
Then both blocked more types of sound waves, but reduced vibration twice.

After all of that, the window is really loud.
A double pain would fix that..

In the end, a loud stereo or earplugs work really well.

I wear these on the highway when I have the roof off and the windows down (which is usually all the time). Really cuts down on the fatigue factor on long trips.

Hi Ernie,

Just had to say hello and the car does look great. It has been a couple of years since we moved to Oregon.

I have used Dynamite and the only thing is that it is expensive; I believe I will go the Fatmate or what Andyrew suggests. I personally want to stay away from the spray ons since over time they appear to collect rust. Underneath I have used rubberized adhesive paint.

Again, the car looks great.

Steve Hurt

Even if it would be helpful, no treatment on the engine side for me. I just finished paying to fix rust in the firewall so we're not going there again.

I have pretty reasonable expectations of how quiet a 914 can be so I think I'll be fine with interior treatments only.

Earplugs, like Elliot said, work wonders, especially on the highway next to trucks.

Rich

Your car looks great!

I went with Fat Mat Rattle Trap and installed an aftermarket heat/noise pad from 914 rubber (that won't hold water) on the engine side of the firewall. I am very happy with the noise level in my teener:

http://www.amazon.com/FatMat-Self-Adhesive...rds=rattle+trap

I suggest not one huge sheet on the floor boards. Leave the channels on the floors open, so if moisture collects in them, it can dry out.

[quote name='ThinAir' date='Nov 25 2015, 04:16 PM' post='2269580']
This is me, picking up my freshly repainted 914 from PMB Performance.

Click to view attachment

Now that it's home, it's time to start putting things back together.

I'm looking for sound deadening solutions for the floor and interior back panel. I'm planning on keeping the interior back panel, but figured this would be a good time to enhance it with some sound deadening capability.

My searches haven't been very successful. I'd appreciate it you guys could offer some advice or point me to previous threads on the subject.
I used the same as CAIRO (Dynamate), it is very easy to work with and dampens any vibration I was having. And yes my dynamite came with a handy roller. I used heavy 2" AC foil duct tape at the seams and it really came out nice. I like you choice of color. Nice car. Mike

[quote name='ThinAir' date='Nov 25 2015, 04:16 PM' post='2269580']
This is me, picking up my freshly repainted 914 from PMB Performance.

Click to view attachment

Now that it's home, it's time to start putting things back together.

I'm looking for sound deadening solutions for the floor and interior back panel. I'm planning on keeping the interior back panel, but figured this would be a good time to enhance it with some sound deadening capability.

My searches haven't been very successful. I'd appreciate it you guys could offer some advice or point me to previous threads on the subject.

I used the same as CAIRO (Dynamate), it is very easy to work with and dampens any vibration I was having. And yes my dynamite came with a handy roller. I used heavy 2" AC foil duct tape at the seams and it really came out nice. I like you choice of color. Nice car. Mike

I've been meaning to write up my project since I haven't seen anyone on our site use them, but, well, you know.

I opted for http://www.sounddeadenershowdown.com/. At a minimum I recommend reading through his site before making your decision. I'm happy to share my BOM, it was definitely more than I needed, so you could bring the price down. The Mass Loaded Vinyl is very heavy so the shipping isn't that cheap.

Basically it's a 3 step process to stop resonance on panels, block vibrations then add a barrier. It's a DIY job.

End result? It's definitely quieter, now I notice how much wind noise we get. As someone else mentioned the rear glass is another weak link. You can definitely improve things, but our cars are never going to be quiet. My doors now shut with a more satisfying/modern thump.

Another bonus is that besides the tiles, none of it is glued in or stuck on, so you can easily remove to inspect for water/rust. If you've gone to the trouble to clean up the tar boards and repair any rust you found, setting it up to do it again seems like a bad move to me.

Replacing the carpet pad with dynapad will make a noticeable difference. Doesn't need to be glued, so water ingress isn't a problem.

Kelly

I'm in the middle of soundproofing my car (912E).

I had stripped the entire car down to bare metal, all soundproofing/tar strips out and MAN was it loud. My plan is to cover the entire rear seat and deck area (over the engine and trans) with hushmat, then about 50% coverage for the floorboards and other panels to quell vibration. I will then cover as much as possible with a 3/8" self adhesive foam mat from super sound proofing. I am sourcing my carpet set from classic 9 leather shop and going for the poly foam backing which Rob says is quieter than the OEM style backing. So far the Hushmat and SSP foam combined has added about 17 pounds of weight. Not sure on the carpet set weight.

So far, I have covered the whole rear deck and seat area and passenger side floor, and there is a marked improvement. I can not hear tire noise over the engine/trans ;-). Some say it is a waste to cover the entire area with the dynamat type materials because they are primarily vibration and resonance inhibitors, but I've seen a real reduction in sound coming through the engine firewall.

LOTS of options, but being budget conscious, I got the hushmat on a firesale from Eastwood last year, and the SSP is fairly cheap IMO. http://www.supersoundproofingsales.com/SSP...o/09-42720-PSA/.

The Pelican forums also have some extensive sound proofing threads.

I know people will scream about the dangers of undercoating, and they are probably right, but one my 914s has what appears to be a rubberize coating sprayed under the entire chassis (and i believe inside the doors as well) and the difference between this car and every other 914 I have been in (which is a pretty large number) is very noticeable. Riding in it the car feels much more solid, quiet, much like 911s i have driven.

I can't imagine anyone would want to add a rubberized coating on a restoration, but thought i would add feedback from a car that has it. I would really like to hear feedback on, or experience, a car that has had the lizardskin product applied to the entire chassis and see how it compares as it sounds like a safer way to achieve a similar result.

[quote name='r_towle' post='2269668' date='Nov 25 2015, 05:25 PM']
Lots of good info here and online.

My two cents.
Sound deadening is about stopping both sound waves and vibration.

Certain materials stop certain sound waves.
Product like dynamat at rubber-foil which blocks two types of sound waves.
It also builds up the thickness of the metal to reduce vibration.

I would suggest a multi prongs approach.
Ceramic spray on sound deadened on the engine bay side.( lizard skin is on product)
1/2 inch foil faced mat on the engine bay side (914 rubber has that)
Dynamat on the inside.
Then both blocked more types of sound waves, but reduced vibration twice.

After all of that, the window is really loud.
A double pain would fix that..

In the end, a loud stereo or earplugs work really well.

I have my original rear glass and the lightweight one that Mark produced, any ideas on how to double them up without possible sweating between the two?

Running a plastic tube between the two at the top and bottom maybe would do it..

I have a '72 Pantera I built for street/track use (roll cage, etc.). I wanted to civilize the car while minimizing weight, so I applied both a Lizard skin sound control coating AND a Lizard skin heat barrier coating to the entire interior of the car while it was apart. I haven't weighed it, but I estimate it added less than 10 lbs. to the car. No extra Dynamat, etc.

The Lizard Skin coatings work really well. The car sounds solid, no "tin can" feel at all. And with the windows up, even the engine noise isn't bad. I was expecting a lot worse: it has a 438" solid roller stroker Ford V8 (660+ dyno HP)exhausting thru a single big Magnaflow straight thru muffler (4" ID, IIRC) designed for turbo diesel trucks.

So I can recommend the Lizard Skin route for sound control, particularly if you want to minimize weight (it also doesn't add any appreciable bulk under carpeting, either). The only downside is the application has to be done while the car interior is removed.

Jack