"Sound proofing"

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I used the 2mm silent coat under the std rubber matting and it did a good job - the doors also ent from a rattly thin crash to a nice thud when soaked. Money well spent IMHO
 
yalan said:
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I used the 2mm silent coat under the std rubber matting and it did a good job - the doors also ent from a rattly thin crash to a nice thud when soaked. Money well spent IMHO
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Thanks Yalan. That is pretty much what I intend to do in the front. I'm well on the way to covering the rear tub. Photos to follow
 
If you want to find leaks, take your Land Rover to a car wash. Sticking stuff over the floor is asking for trouble. It will trap water where it can't be seen. If you want a quiet car buy a BMW.
 
Sofasurfer said:
If you want to find leaks, take your Land Rover to a car wash. Sticking stuff over the floor is asking for trouble. It will trap water where it can't be seen. If you want a quiet car buy a BMW.
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Err I have done the whole pressure spray from outside and almost nothing came in. The water has been seeping in on an obscure pathway that is not immediately visible otherwise I would have found it by now. And as per the original post I don't want a quiet car, just a slightly less noisy one. Been there, done the BMW and sold it for something more fun many years ago :)
 
NickMcKee said:
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.
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So here's an update on my progress so far...

I've removed the bench seat on one side and the middle row. I will do the bench seat on the other side when I recover a bit of strength as it was murder getting the others off. I think I sheared about 3 or 4 of the bolts despite soaking then in WD40 for a few days and cleaning off the threads (and having a waxoyled chassis). The middle row mounting points on both sides are in a bad way. I'm thinking I need to cut out the rot and replace the aluminium. If anyone has any wisdom on this them I'd be really grateful.

I've also removed the cubby box and both front seats together with the Land Rover factory trim.

Having done all of that I've now covered most of the tub, under the front seats and under the cubby box with the silent coat. I'm glad I got the 2mm as it is very easy to work with. It is easy to cut to size and easy to shape around the corners and curves of my 110. I've been careful not to cover any nuts, screws and to make sure the access panels under the seats and cubby box are all fully available. I'm covering the joints with some thin alu tape. I'm not sure how necessary it is as the silent coat is semi-solid and so sort of flows to fill the joints. The rubber reminds me of the butyl based dum-dum replacement I use. This consistency makes me more confident about using it in a defender because I think it will be 'self healing' and that combined with it being seriously sticky means that it will be very hard for water to get underneath it.

I've held off doing the footwell / bulk head / transmission tunnel because I am trying to track down two minor leaks in that area: one the driver's side and one the tunnel. I think the driver's footwell may be via the clutch even though it appears on the throttle.

I've used over 4m2 so far. I think it will take 6m2 to do the whole of my 110 but I have 8m2 available just in case.

So far I'm happy - and grateful to my family for pitching in and giving me so much help.

I can't figure out how to add more than one photo to a post and so I'm going to pop a few in as separate posts.
 

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