hexagone

Has anyone added dynamat (or equivalent) to their car?

Looking to get my exhaust noise with the windows down but a quieter (and rattle-free-er) interior with the windows up. So I was curious if people have done it, where they've placed it, and overall input.

slowslowcar

From my experience it doesn’t really help unless you strip the entire car and layer it (even then I’m not sure how much it helps, but adds a ****load of weight).

it def won’t solve the rattles. I buy automotive cloth tape and chance down the rattle and put a thick piece there. It’s usually plastic on plastic that’s rattling

PapaC4S

Dynamat or any constrained layer damping (cld) tile will stop panel vibration. To isolate and block noise like exhaust or tires, you need to put a layer of mass loaded vinyl(mlv) backed with closed cell foam(ccf) under the carpet. This is a picture in process. You need to seal all the seams. Treat noise like water. It will work its way through any crack. Lot of work but it works great. I have a quiet car now.! Added about 40 pounds.

BucketList

I have installed it before. You can get significant noise reduction without plastering the entire car with it. It does add weight but we are talking 20-40 lbs not more. You have to use the roller tool to flatten it onto the metal surfaces. If Porsche already put damping material on the sheet metal, it won't help. It's meant for sheet metal without any deadening. I installed it on the inside doors under the cover panel and the inside of the outside door sheet metal in places. I also used it on the trunk lid. I didn't cover the floor as the batting was glued down and pretty good already. The result was pretty impressive. I did not measure db but it was noticeable. Now the car was not super noisy to begin with but it was much improved with Dynamat. The Porsche is so loud, I don't know if I would bother doing this, but if you do, I would be interested in the outcome. My current thinking is that this car is too noisy to invest in any audio.

jamesinger

Since I have only bought used cars, I've had to go through them all very carefully. With most of the cars I have owned, this means methodically going through and checking every single bolt. I find it calming and it makes it so I know the car but I get that a lot of people don't want to do that. In all cases but 2, this solved all rattles. One that I couldn't get was the door cards on an EVO (typical mitsubish!t). I ended up just taking them off, going through them, and putting them back on really carefully, which solved the issue. The other was in the trunk of a EM1 civic coupe, where I couldn't get it. I knew it was either the exhaust, which was a DC ITR JDM set up custom piped for an EM1 or a thin enclosure tucked 12" sub box. Since I couldn't really diagnose it further than that, I put down some dynamat in the trunk area and it solved the issue with some experimentation (i.e. I didn't just add it like a carpet but more like pictured above). In the end, I am positive it added less than 10lbs and it made it so I could drive the car from LA to my parents house up near Tahoe without going mad.

OKB

I did 2 cars, the whole rear area and alot under the front pan and odd areas. It does have good results. The more you do the better the results.

TheTorch

As others (esp @911-targa4s) have said, Dynomat is for vibration dampening, MLV + closed cell foam is for sound blocking and absorption.

I pulled the entire interior floor and rear seating, tunnel, rear interior quarters, etc. down to metal on my 69 911 that has a 3.2 with PMOs. It was loud inside. Like hard to converse loud. I added some Damplifier Pro (similar to Dynomat), but not 100% coverage -- that's not necessary and adds weight. Install in large flat areas at about 25% coverage.

The key is the MLV + CCF:

Then I covered everything with Second Skin Luxury Liner Pro (MLV+Foam combined in one) before installing new carpet. Made a huge difference. LLP is about 1.25 lbs. per SF. Removing my old junk and replacing with the modern materials probably added about 25 lbs total, but 100% worth it. For you, just doing the rear seat area isn't going to add that much weight.

These guys have good explanations of the purpose of the vibration damping and sound blocking / absorption materials. https://www.secondskinaudio.com/sound-blocking/

There are some tricks:

• Use 1/4" self adhesive Dynoliner (not Dynomat) to smooth transitions of the LLP or where the LLP cannot make a smooth bend. Otherwise, you get sharp edges on some contours that can show through the carpet.
• For LLP, they recommend using foil tape on seams. I found it did not bind well (I tried 3 brands of aluminum tape) before deciding it wasn't bonding strong enough). I don't think that mattered much.
• LLP has to be glued using a high quality Vinyl adhesive: DAP or HH66. Use a ventilator and a fan. Nasty.
• The added thickness can cause fitment issues with things like the rear quarter covers and seat bolts. Plan ahead and it's ok.

I highly recommend doing this.



rear seats, deck, floor, tunnel, quarters

front

after buttoning it back up

PapaC4S

Good point Torch. I forgot you need to carve out the foam under the carpet pads to make room for the MLV layer so some weight saved there.

TheTorch

ha. 997 isn't so bad. On a 69, they used tar covered jute as insulation. Foul smelling and nasty to clean off after 50 years: