"Sound proofing"

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NickMcKee

Member
Posts
68
Location
Bolton
I thought it was about time I chipped in with some help for others...

I have been looking at options to reduce the noise levels inside my Defender. Let's be honest - it's about reduction not sound proofing. If you want a quiet vehicle buy a Nissan Leaf.

Now there is a lot of info about noise reduction on this an other forums. Some of it is really helpful but some is, well, a bit weak to put it politely.

There is a lot said about how the only way to reduce noise is to add mass. Bigger, heavier rubber etc is a common stock solution. From my engineering days I know it is more complicated. There are also people out there who think that something like dynomat is basically an over priced bitumen roofing produced. It's not.

I used to work for the (then) largest butyl rubber manufacturer in the world. Butyl is really hard to make and so it is expensive but it also has some remarkable properties. One is that it absorbs vibration in a way that is way beyond the ability of most other rubbers. We used to demonstrate this by dropping two balls - one made from natural rubber and one made from butyl. The natural one would bounce back into the air, the butyl one would almost stop dead in its tracks. In not very sciency terms, the natural rubber one released the vibration energy back out again while the butyl one absorbs it even though they were basically the same weight.

Noise is vibration. Vibrating panels transfer noise by vibrating the air. More vibration, more noise. By fitting a vibration absorbing material to a panel, it vibrates less and so vibrates the air less, and so becomes quieter. This can be achieved by adding lots of mass but it can also be achieved by adding less mass of a better absorbing material. Sticking with the natural rubber vs butyl example, I don't have any scientific test data but it is common sense that 2mm of butyl will absorb a lot more vibration than 2mm of natural rubber. Purely guessing, it wouldn't be surprising if you needed 4mm of natural rubber to get the same reduction but that would weigh twice as much. So it's not simply a question of adding more mass, what that mass does with the sound energy is important.

Of course 'soft furnishings' are great at absorbing vibration (and therefore sound) but if your defender leaks then it has to be closed cell material or you will be driving a rotting sponge in no time.

As for the bitumen roofing material, it is not made from butyl, it's closer to road tar than any rubber material. Those smells that people comment on, they are the volatile bits of the tar evaporating and I wouldn't expect them to be good for you. Lots of aromatic oils are carcinogenic and so I would be amazed if the roofing materials are designed for use in a confined space such as inside a defender, even if it does by design and default allow a lot of air flow through the vehicle. Just on health grounds I would give them a wide berth.

So what I'm I going for? I've already got some camping mats under my head lining. Next step is some 2mm butyl based material for the entire floor pan. I'd prefer that it didn't have an aluminium coating as that will reduce the effectiveness a bit but it's not readily available. I'll see what that does before I do anything else.

Hope this helps.
 
Very useful and helpful. :)

I have used 1" cow/horse mat rubber to good effect in the back and closed cell foam all over and around seat box.
Fitted one of those over priced mat systems under the feet and tranny tunnel and insulated the bonnet.
Then (and here's the rub) self adhesive anti vibe stuff on any flat panel I could find and guess what it's the bitchumen stuff - oops!
I wish I had known this about Butyl before o_O looks like I'll be dying slowly from the vapors - ho! Hum!
Even now not enough sound proofing to be comfortable - still need to lag the clackety bit at the front - oh and my air intake booms!!

Be interesting what you do with bulkhead and engine bay.....:cool:
 
I thought it was about time I chipped in with some help for others...

I have been looking at options to reduce the noise levels inside my Defender. Let's be honest - it's about reduction not sound proofing. If you want a quiet vehicle buy a Nissan Leaf.

Now there is a lot of info about noise reduction on this an other forums. Some of it is really helpful but some is, well, a bit weak to put it politely.

There is a lot said about how the only way to reduce noise is to add mass. Bigger, heavier rubber etc is a common stock solution. From my engineering days I know it is more complicated. There are also people out there who think that something like dynomat is basically an over priced bitumen roofing produced. It's not.

I used to work for the (then) largest butyl rubber manufacturer in the world. Butyl is really hard to make and so it is expensive but it also has some remarkable properties. One is that it absorbs vibration in a way that is way beyond the ability of most other rubbers. We used to demonstrate this by dropping two balls - one made from natural rubber and one made from butyl. The natural one would bounce back into the air, the butyl one would almost stop dead in its tracks. In not very sciency terms, the natural rubber one released the vibration energy back out again while the butyl one absorbs it even though they were basically the same weight.

Noise is vibration. Vibrating panels transfer noise by vibrating the air. More vibration, more noise. By fitting a vibration absorbing material to a panel, it vibrates less and so vibrates the air less, and so becomes quieter. This can be achieved by adding lots of mass but it can also be achieved by adding less mass of a better absorbing material. Sticking with the natural rubber vs butyl example, I don't have any scientific test data but it is common sense that 2mm of butyl will absorb a lot more vibration than 2mm of natural rubber. Purely guessing, it wouldn't be surprising if you needed 4mm of natural rubber to get the same reduction but that would weigh twice as much. So it's not simply a question of adding more mass, what that mass does with the sound energy is important.

Of course 'soft furnishings' are great at absorbing vibration (and therefore sound) but if your defender leaks then it has to be closed cell material or you will be driving a rotting sponge in no time.

As for the bitumen roofing material, it is not made from butyl, it's closer to road tar than any rubber material. Those smells that people comment on, they are the volatile bits of the tar evaporating and I wouldn't expect them to be good for you. Lots of aromatic oils are carcinogenic and so I would be amazed if the roofing materials are designed for use in a confined space such as inside a defender, even if it does by design and default allow a lot of air flow through the vehicle. Just on health grounds I would give them a wide berth.

So what I'm I going for? I've already got some camping mats under my head lining. Next step is some 2mm butyl based material for the entire floor pan. I'd prefer that it didn't have an aluminium coating as that will reduce the effectiveness a bit but it's not readily available. I'll see what that does before I do anything else.

Hope this helps.
I've just used Noise Killer and it's defi itely taken the edge off of the noise. Dulled it at least and I've still not finished the doors or rear footwell or roof so maybe further reductions to be had.
 
Silentcoat (like Dynamat) which is butyl, used in conjunction with closed cell foam over and decent carpet made my 110 nice and civilised
An added benefit was condensation, seems to have reduced that too, was a lot drier last winter.
 
I've just used Noise Killer and it's defi itely taken the edge off of the noise. Dulled it at least and I've still not finished the doors or rear footwell or roof so maybe further reductions to be had.
Thanks for this. I was going to go for Noisekiller but they use open cell foam as part of their construction. Open cell = sponge and I have way too much water inside mine to risk having a sponge lol
 
Thanks for this. I was going to go for Noisekiller but they use open cell foam as part of their construction. Open cell = sponge and I have way too much water inside mine to risk having a sponge lol

Try and dry up the leaks first. But in practice they aren't a problem unless you use carpet or something very absorbent.
Cut the noise mat to fit footwells and underbonnet, trya and stick some inside the doors too if you CBA. Dont forget the rear loadspace if you have hard top.
Heavy rubber mats on top of the soundproofing material help, and protect the expensive sound mat.
 
Silentcoat (like Dynamat) which is butyl, used in conjunction with closed cell foam over and decent carpet made my 110 nice and civilised
An added benefit was condensation, seems to have reduced that too, was a lot drier last winter.
Thanks Jim. I've ordered 2mm silent coat- cheaper than dynamat and they imply it has more butyl in it. Once I've got the silent coat in I will figure what goes on top. Did you hit the closed cell on top of the silent coat? And what thickness did you use?

I'd like a bit of carpet in places to make it quieter but I have a lot of water coming in which I'm struggling to stop.
 
Thanks Jim. I've ordered 2mm silent coat- cheaper than dynamat and they imply it has more butyl in it. Once I've got the silent coat in I will figure what goes on top. Did you hit the closed cell on top of the silent coat? And what thickness did you use?

I'd like a bit of carpet in places to make it quieter but I have a lot of water coming in which I'm struggling to stop.
2mm is pretty thin. The stuff I used in my Ninety was about a centimetre thick.
 
Thanks Jim. I've ordered 2mm silent coat- cheaper than dynamat and they imply it has more butyl in it. Once I've got the silent coat in I will figure what goes on top. Did you hit the closed cell on top of the silent coat? And what thickness did you use?

I had some closed cell under manky/ rotten carpet when I bought the 110, I threw away the carpet and put silent coat 2mm everywhere including inside doors, then under the new carpet I reused the closed cell on the transmission and floor areas (it was approx 8mm closed cell foam sandwiched between heavy outside layers)
I only went for the 2mm silentcoat as with the foam and the carpet I thought that would be enough
Made sure I nailed the leaks before shelling out £££'s to Exmoor Trim for a carpet set :)
 
Thanks Jim. I've ordered 2mm silent coat- cheaper than dynamat and they imply it has more butyl in it. Once I've got the silent coat in I will figure what goes on top. Did you hit the closed cell on top of the silent coat? And what thickness did you use?

I'd like a bit of carpet in places to make it quieter but I have a lot of water coming in which I'm struggling to stop.

Think this is the one I used. It was few years ago. I already had the trans tunnel cover etc. just did the footwells, doors, and underbonnet. And the loadspace.

Made a huge difference, a 2.5TD Ninety is very noisy. I can hear the stereo now, even at speed! :)

https://www.nkgroup.co.uk/product/full-land-rover-soundproofing-kit/
 
Thanks Turboman

My ex MOD 110 SW with the sum total of 2 rubber mats on the floor is not exactly quiet :)

I decided not to go for the NK stuff because they use open cell foam as part of the kit. Otherwise I would have gone for it, especially as they are fairly local to me.

The 2mm is only a starting point but I expect it to make a big difference because it will absorb a lot of the vibration because it is made from butyl rubber. I'll probably pile on some closed cell foam and/or some MLV on top but first I want to test the silent coat by itself (well with my 2 rubber mats as well of course!)
 
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I had some closed cell under manky/ rotten carpet when I bought the 110, I threw away the carpet and put silent coat 2mm everywhere including inside doors, then under the new carpet I reused the closed cell on the transmission and floor areas (it was approx 8mm closed cell foam sandwiched between heavy outside layers)
I only went for the 2mm silentcoat as with the foam and the carpet I thought that would be enough
Made sure I nailed the leaks before shelling out £££'s to Exmoor Trim for a carpet set :)
Thanks - this makes good sense to me. I'll let you know what I end up doing.
 
Thanks Jim. I've ordered 2mm silent coat- cheaper than dynamat and they imply it has more butyl in it. Once I've got the silent coat in I will figure what goes on top. Did you hit the closed cell on top of the silent coat? And what thickness did you use?

I'd like a bit of carpet in places to make it quieter but I have a lot of water coming in which I'm struggling to stop.
Get those leaks squared away. Not as hard as you think.
 
Struggling a bit tbh but not given up yet. Roof lining out again today and the hunt for the roof leak will be on again tomorrow.
A great trick is to close all Windows and flaps and let a smoke bomb off inside. I can't remember who on here did it but they claimed the whips of smoke gave away all the leaks whilst he ran around.marking them all with a bright crayon.
 
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