Sound Insulation

[Maxspeed]

Adding layers of insulation to the floor pan under the carpeting will have limited improvement only.

To be really effective, U need to sandwich the floorpans with bitumen together. In other words, apply bitumen to the floorpan under the car as well. That will stop the vibrations dead. Sandwiched panels are used throughout in lexus vehicles, floorpans, firewalls, boot,...etc.

 

Also, remember the saying "empty vessel makes the most noise". The vehicle chassis actually comprises of a structure of tubbings(voids) that potentially resonant and transmit noises into the cabin. U need to identfy them and fill them with expanding foam. They can be found at the A-pillar, door structure, wheel arch, engine bulkhead, doors, beams, firewall...etc. U need to remove carpeting to access them. The foams expands, fills these voids & kills noise transmission. And also stiffens the body. This is also extensively used in lexus cars.

 

Get these done up right & substantial noise reduction(not insulation) can be realised.

 

However a point to note is that, the amount of sound proofing is still dependent on the thickness of the car's glass. Usually 3mm only. Sigh!

[Sturtles]

hmm... so those spray on tar for the undare carriage is effective?

 

Cuz I've heard people doing the rust proof package that comes with noise killer for the bottom, but from what I've heard, it doesn't help noticibly

[Apollo]

done soundclad also, can say dun bother wasting this type of $$$.

 

but if using rubberized coating, spraying at the weathershield (banana leaf) does help. cos it is something like bituminous spongy material, which is unlike the solid surfaces of the banana leaf. so the cell molecules will not transfer sound pressure (energy) as well as solids. but real effect is to protect inside the banana leaf.

[Maxspeed]

Undercarriage sprays are ineffective & a waste of money.

 

Do the sandwiched panels & expanding foam in the body voids. They are definately effective but a lot of work.

[Sturtles]

Thanks for the advice brother, If its not too expensive, I like to try.

 

Where can I get them?

[Sturtles]

Hi bro, have you done the sponge coating?

 

bkknight filled his front fender void with fibre, but from what he said, it doesn't help

 

I'm interested in doing it if not too expensive, like to do it together? maybe can get avalanche to do it as well... kekeke

[Apollo]

not sure what fibre he does... but i would say for my case, it was 3-6 layers of bitumen in that arch, followed by a layer of areoflex.

there is however a inherent problem wif lancer. cos where the front door meets the front fender, there is a thorough gap. so, once the noise premeates thru the weathersheild probably coupled with reverberation of the shield, the noise becomes louder. U need to seal that off for sure.

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another ancillary issue is the top rainwater gutter just under the front screen. that plastic piece is hollow and if u put ur hand into the engine bay n tap, the person in the front seat will hear it as well. what i've done was to add a layer of aeroflex there as well.

 

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lastly, the CMI yoko tyres will give noise after 10k km. this increase the problem.

[Maxspeed]

The expanding foam comes ready in spray canisters. They can be had for about $9/can from good DIY stores.

[Eagle0405]

Bros,

Spend more $$$ and go for sound insulation sheet by experts. Less than $90 per door and believe me , worth the $$$ and effort. Last time, tried to do my own soundproofing and it was alway a half-baked result...

 

To save $$, U may ask them to do 2 doors first and learn the trade before doing yourself. This way, Save $ a bit lor....