fatmat made my car ride worse?

jedge1.8t

Junior Member
Hi, I just got done doing a soundproof attempt ot my audi TT. Its not completely finished yet but heres a few pics at the bottom.

I used fatmat which is cheaper to dynamat, I doubled layered it all over the car, roof floor, doors, trunk, just not firewall. and it significantly reduced the vibrations. On top the fat mat i layered everywhere with dynaliner or carpet jute (padding) to deaden the sound.

I also, which Im starting to regret dearly stuffed all the internal body frames with carpet padding then sprayed great stuff all inside to to adhesive it to feel solid rather than hollow echo vibration.

Now while I feel I almost eliminated all the outside sounds, my suspension and tire noise i feel has increased... like twice as much, the annoying thing is i hear it even with my windows down.

The big issue I have is my car sounds like it has cheap rims on it, but there the stocks and before i never had this issue. tires are sport v12s, but dont remember them being so loud.

So any ideas what i can do to resolve this? do you believe filling the body structure gaps with great stuff caused this??

I cant decide if the eliminated vibrations and outside noises opened just enhanced the road noise, or the fatmat, carpet padding and foaming the stucture pockets incresed the road noise.

 
some things about noise:

1. as you eliminate one source, other sources become dominant and more noticable.

2. sound travels easily through hard surfaces.

3. as you change stiffness you change which frequencies are most easily transmitted.

4. the best noise isolator is two layers of mass separated by dead airspace.

5. all barriers have a resonance frequency in which sound is easily passed through.

carpet padding doesn't absorb much sound, but when stuffed in cavities it can help at some frequencies.

expanding foam is useless and does more harm than good. as it hardens it increases sound transmission, not decreases, since it rigidly connects to surfaces that used to have an air-gap separating them.

if all you wanted to do was reduce road noise, you should have used Mass Loaded Vinyl, not FatMat.

 
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