Soundproofing insulation

[Keyo 47]

It works well chap sticking the new insulation to the old rubber lining, its mad my car smells like a new car now from factory because of the glue. I had to do mine because of the coolant leak but chuffed they are now done. I was quite impressed with the stock insulation , basically 3 layers in the front and two in the back.

[fla 9]

I've now fitted the following:

 

6mm closed cell foam adhered to 10mm dense open cell foam covered with tecsound mass loaded vinyl.  this is on the floor area of the car., up to the bottom edge of the dash. Closed cell foam towards the ground (noise source)

The drivers door i've tried a combination of 3mm closed cell foam covered with 10mm dense open cell foam with some black self adhesive felt.  This has been stuck to the door card with the closed cell layer towards the door skin.  

In the boot, i've put a cut-off from a landrover bonnet insulation panel under the booth carpet above the tyre.  I've removed the old flaky bonnet insulation but not replaced it yet - this may be a source of noise as it might be coming straight from the engine, through the bonnet and through the bulkhead.

 

Still seem to be getting more noise in than i would like - just wondering if anyone has done the bulkhead when the dash was out and if so the kind of results you had?  I'm also thinking that noise must be getting in from the seals somewhere.  If so, this will be the plan for next summer...

 

Any other areas people have insulated with good outcomes?  Any replacement seals make a difference?

 

Thanks

 

Hasan

[oneohtwo 8]

Did you get any further with your sound proofing? I was looking at making the Corrado a bit more hospitable on long drives so was thinking about sound proofing. I have looked at this company to source materials from and the ranges seem simple to understand and they have a few guides.

Sound Deadening Shop - Car Van & 4x4 Automotive Sound Proofing

They seem to generally recommend a two stage process, which pretty well follows what you outlined:

1) Damping/deadening layer onto the metal panels, such as:

Dodo Mat DEADN Hex Sheet – Sound Deadening Shop

2) Sound barrier, mass loading vinyl with the closed cell decoupling layer over the top:

Dodo Barrier Pro – Sound Deadening Shop

Which all sounds pretty straightforward, but I notice they don't included an open cell layer for sound absorption. I'm just wondering if that would still be useful, and then whether if you did that, that would go over the top of the MLV? They also sell this:

Dodo Sound Stopper Pro v2 – Sound Deadening Shop

Which does have open cell foam, a layer of MLV, plus a PU layer, so looks like more of a 1 stop shop, I assumed the PU would be a closed cell decoupling layer and be the side placed against the panels, but they describe it as the face, and protecting the open cell foam beneath, so I am a bit unclear on that. I thought open cell foam wouldn't work as a decoupling layer?

Also, how much do you think your install weighed in the end?

 

[fla 9]

Some shops just sell product without any explanation of how or why or what, although others provide details on what the products do.

CLD (Constrained layer damping) material like Damplifier (as i have used), Dynamat or that Dodo Mat essentially aid in reducing panel vibration - which causes the tinny noise you hear on some car doors.  To be honest this doesn't really affect/reduce road noise to a great extent. It is better for improved acoustics from your sound system as the panels then dont vibrate. What you need for that is an open cell foam which will absorb airborne noise and convert it to low grade heat energy.  The problem is open cell not only absorbs noise it also absorbs moisture! So there is a belief that closed cell foam does the same but is better as it does not absorb moisture.  Not really true - closed cell foam does indeed absorb sound to a lesser extent but is essentially a decoupling layer.  You then overlay this with a mass loaded layer like mass loaded vinyl which acts as a blocker for any sounds.  This must be decoupled from the body or any panel otherwise it can actually cause the sounds to be amplified.

 

So your layers need to be (in this order from the noise source):

 

Stick-on panel damping (Damplifier)

Closed Cell foam

Open Cell Foam

Mass loaded vinyl

The issue again is the thickness of all of these - put them on the floor and your seats wont fit back in.  

I haven't done the bulkhead on mine but might get a cheap sound meter to try and isolate the actual sound location.  In theory most noise comes through the floor and doors, but it may also be that a superior type of door seal is also required, which i will look into.

Hope that helps

 

Hasan

[dragon green 4]

When I didn’t have my parcel shelf in, it seemed really noisy !
I dynamatted the boot area,two carpets, open cell stuck to the underside of parcel shelf, and inside tailgate where I could get it, really made a difference to exhaust and road noises.
Also dynamatted under rear seats, rear door panels,a cheaper insulation stuck on rear of A,B&C pillar trims, still not as quiet as I want it,

[fla 9]

thats a good shout Dragon - the rear parcel shelf. Did it have any effect on the struts holding the boot lid open?

Its an iterative process as no sooner than you've sorted one noise source you find another.  Plus rattles and squeaks then tend to become more noticeable..

 

Hasan

[dragon green 4]

thats a good shout Dragon - the rear parcel shelf. Did it have any effect on the struts holding the boot lid open?
Its an iterative process as no sooner than you've sorted one noise source you find another.  Plus rattles and squeaks then tend to become more noticeable..
 
Hasan

No problem with the struts,as the insulation is so light


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[oneohtwo 8]

Thanks Hasan,  gonna do a bit more reading around the subject before taking the plunge I think. Find out a bit more about the different products.

Just a question though, how long did your install take you? Wondering if it's an easy weekend job.

[fla 9]

doing the floor was a weekend job comfortably.  Its more time consuming removing the interior.  But once that's out i just laid out the rolls in the car, roughly marked them, cut the rough marks and then tidied them up outside the car.  I didn't bond the layers, perhaps its better to do so but thinner single layers are easier to manipulate and position. 

Doors have been trickier as i tried to trace around the old foam, which firstly wasn't that easy to remove in one piece and then secondly kept sticking to the new insulation.  I've only done the drivers door so far so need to complete the remaining three panels at some stage - need to make some time to complete, tbh.  But the car is SORN'd at present, so I've been a bit lazy, with in fact another project (yaris 1.5 t sport) for my son

[dragon green 4]

Has anybody tried insulating the door skins ?

Did it make any difference ?

 

I know back in the day Kevin Bacon’s old car was a “demo” car , for in car entertainment (I think) there was insulation everywhere, but it was never as quiet as he wanted

[fla 9]

I've done the outer skin to prevent vibration, but only done one door card with open cell insulation. There's very little space between the door card and inner skin which means the insulation really needs to be thin....which again reduces its effectiveness. Its made a difference but i want to identify the noise source properly as the existing foam inside the door card does help a bit. And allows the door card to fit back properly too!

Hasan

[oneohtwo 8]

Right, stripped out the interior and found the worst possible result - under the carpets (which have always been dry) in the footwells everything was absolutely soaked. Not entirely sure where this has come from. I had a matrix leak years ago but thought that had all dried out at the time. Perhaps it was just the carpets. It reeks under there as well. no idea how the smell didn't come out before.

Anyway the upshot is that the factory felt material is beyond usable - so question is when you did your soundproofing did you put back the factory felt after you laid your new stuff, or did you remove it all completely and just use your closed/open cell foam layers? Edit to add, having thought about it more it would surely just be the new foam otherwise it'd all and up too thick. 

Second question though: I've had to peel off the grey panel dampers as they were soaked, but it's left a load of black bitumen/asphalt/whatever that was sticking it down. How best did you get this off? just scrape it off with a bit of heat I guess?

Second Edit - Actually the black stuff is under the paint in the footwells, just an underseal type stuff I guess. What has happened is that the grey deadening has pealed the paint off revealing the black stuff, and it was such a mess under there I couldn't tell what was what. So having scraped some of it off I am a bit stuck. Any idea exactly what this stuff is and how I can replace it? Thinking it may have been better to leave the grey dampeners stuck down and let them dry out in place as they are obviously plastic things. Bah. 

Edited September 5, 2021 by oneohtwo

[1xshaunx1 27]

When I did my new carpet from Newton Commercial I also got their delux under carpet set which is 2 layers of sound deadening underlay  fibre stuff, used both for both front foot wells and one for the rear. The other I rolled up and shoved under the rear seat cavity. Kept the original centre tunnel sound deadening 
 

[oneohtwo 8]

Unfortunately the centre console sound deadening was also pretty rotten so will replace. Did you leave the grey panel dampeners in place?

Any idea what coating they used on the footwells? It's some sort of bitumen paint I think, a few mm thick. I suspect to help with panel damping.

[1xshaunx1 27]

Your right it’s some sort of bitumen for deadening and anti rust, I didn’t touch that. Put my underlay on top of that

[oneohtwo 8]

Thanks, yeah I think I have made a bit of an error there. 

All I can really find is bitumen underseal, and I am not a 100% sure if that is OK to use internally. I presume so, but don't want fumes leaching out! This stuff sounds like similar stuff by the description:

Noxudol UM-1600 Underbody Coating (frost.co.uk)

Reckon it would do the job? I think I'll give them a call tomorrow.

 

 

 

[1xshaunx1 27]

If not, what about something like Noico 80mil. Will be similar to what you scraped off and easy to apply without getting overspray everywhere. 

[fla 9]

The little grey plastic packets are there to turn the sound vibrations into low grade thermal energy.  Generally not used now as there are better products.

Like you say, i would just bin the old felt but might be a good idea to hang on to the heavy mass layer on top.  That is actually your sound blocker.  I have taken that all out and laid some fresh MLV with the foam underneath, but you could just as easily remove the rotten felt and stick some foam in its place to decouple the mass layer from the noise source.  The issue we have is the lack of space - too thick and the carpets etc wont fit back properly.

 

The good thing with reusing the old black panels is that you know they fit exactly and will not allow any sound to pass through any unknown gaps.  

Hope that helps

Hasan

[oneohtwo 8]

On 9/6/2021 at 10:36 AM, 1xshaunx1 said:

If not, what about something like Noico 80mil. Will be similar to what you scraped off and easy to apply without getting overspray everywhere. 

I think you're right it's something like this. What I ended up doing was painting over any small rust spots with Hammerite then using this stuff;

Noxudol 3100 Sound Deadening Compound (frost.co.uk)

Which I could just brush on thick in the areas I scraped off. Was quite nice in that it went on thick so levelled off with the existing stuff.

Finished off the rest of the soundproofing anyway. What I did was strip everything back and put CLD mats on all available exposed panels. I was mostly aiming for under the rear seat, but did the boot as well, plus inside the rear side panels. Wasn't going for 100% coverage as that is a waste of time, money, effort and material. Also without knowing exactly which panels resonate it's a bit of a hit everything approach and hope that at least some make a difference. 

I replaced the ruined factory felt stuff with closed cell foam, and then laid MLV from front to back, basically the whole floor plan. So I do have a continuous layer under the boot carpet, under the rear seats, over the rear seat beam and down into the footwell, and then all across the front footwells to the bulkhead. The footwell MLV extends up the side of the sill as well, so got full coverage instead of just the two square pieces in the footwells themselves. 

Lastly stuck some open cell foam to the underside of the parcel shelf. This looks a bit unsightly and can't see it lasting long so i may see if it makes any difference with this removed. 

Having gone on a long drive it has definitely improved things, and the exhaust drone at motorway cruising is vastly reduced and I can hear the radio again. It's obviously not whisper quiet but dealing with the drone was my main aim so that is a big improvement. Drone still gets a bit high if having to pull up a hill with a bit more throttle, so may still swap the exhaust out.

The downsides:

- With the factory felt ruined I couldn't exactly work out the right thicknesses of CCF, plus I underestimated how much I might need. This means in the footwells the foam is only on either side of the central ridge, and then the MLV and Carpet is sat direct on the metal. In terms of sound and feel under foot it doesn't seem to have made a difference but the carpet doesn't fit quite so well, and is a bit loose in places.

- Similarly either side of the transmission tunnels the CCF is thinner than the factory felt so the carpet isn't "filled out" against the trim so well. There's also a lot more heat coming through this area, so I think I need to revisit this area and get more foam down here maybe the stuff with the metal film on to help. Trouble is it's almost on the wrong side as the heat is already inside the car... It does get very hot down there though, either side of the gear shift, and it doesn't feel like it should. Anyone else get this?