Sound Suppression Question.

Has anyone used some sort of foam/sound suppression foam to fill the voids behind the std rear speaker positions, and how well has it worked?

I don't have any rear speakers, (don't need them) i have used expanding foam on my old S14 which seemed to work well but i also had MDF baffle boards in there as i had a stealth sub setup.

Chiefgroover did this write up

http://www.mkivsupra.net/vbb/showthread.php?t=89645

Thanks Nic, but i'm trying to find out what type of foam, and how well has it worked, before i spend out on the expensive stuff;)

Thanks for posting that link up Nic I hadn't seen it before and especially thanks to Cheifgroover for the write up, excellent work.

I think I'll make this my winter project.

I used sound insulation felt in the rear internal wheel arches. I just put as much as I could get in and I made sure that there weren't any voids which is very important, a layer in the boot aswell.

My brother bought the felt and he can't remember where from, it's like the stuff in the link below.

http://merlinmotorsport.co.uk/product_info.php?products_id=6072?utm_source=Google&utm_medium=Shopping

Everywhere under the rear seats and on the arches under the plastic trim I used at least one layer of dynamat, the dynamat is really just to stop resonance on thin metal panels but it's better than using nothing if there isn't enough room for the felt.

In hindsight it probably would've been better to lay one complete layer of the felt underneath the whole carpet from the front footwell to the boot and everywhere else if there's room, even under the rear seats too but at the time I wasn't sure if they would go back in with a layer of felt in the way ( I should've tried ).

I used foam when i went through a sound proofing phase. Fire retardent acoustic foam. Worked really well. I used it to fill the voids in the rear arches, behind the doors underneath the carpet and behind the aerial and fuel pump ecu.

It really made the car quiet, that coupled with the sound insulation matting on every panel.

edit: a thread with some piccies of what i mean. http://www.mkivsupra.net/vbb/showpost.php?p=1612068&postcount=12

Foams not really the best for suppressing noise. It is good however for stopping echo. To get the best from a sound suppressing material it needs to have density which unfortunatly adds weight to a car. The best stuff to use in a car is a dynamat material its made from bitumin and per sq meter quite heavy rubber matting works well too. Dynamat is quite expensive so just buy chaeper stuff of ebay but try to get stuff with aluminium face as this adds to the density of it therefore stopping more noise!

My old man is an acoustition so any more questions plaese ask

get stuff with aluminium face as this adds to the density of it therefore stopping more noise!

I would use a thicker material for ulimate sound insulation rather than the aluminium faced dynamat or equivalent stuff on it's own.

http://www.dynamat.com/products_automotive_dynaliner.html

Thanks for the replies, interesting, i have already got a form of flashing tape in there, but i just want to add something to fill the cavity as it seems to amplify the road noise, perhaps I'll pinch a couple of cushions and see what the results are, and hope the misses doesn't notice;)