soundproofing material

[fid-def]

Any one use the foil backed stickon sound proofing material on the inside of the bonnet on a defender. Any views on itsvalue there - I chucked my bonnet felt thingy away ages ago and don't know if the foil stuff would be a good alternative.:(

[p38arover]

I made myself a hat from it. :D

For my RRC, I used a pack of thick two layer felt with a bitumen layer between. It had adhesive on one side. I used it on the firewall and under the bonnet. It made a huge difference. What also made a big difference was sealing up all the holes between the engine bay and the cabin. Mechanics for the previous owner had just pushed out grommets when they need to run a cable, etc. It's amazing just how much noise comes in via those holes.

[Ranga]

I got some self-adhesive felt type sound deadener from Rare Spares. Very sticky, durable and cut the noise down a fair bit. About $60 from memory, which was enough to do my defender bonnet.

Sent from the dodgy keyboard on my phone via Tapatalk

[flagg]

I used dynomat brand stuff. Not cheap but works a treat. My very scientific 'ear' sound meter says it works.

[Davo]

I used some of that easy-to-get "underbonnet liner" or whatever it's called, which comes in a roll and is basically a sort of self-adhesive foam. It fell to bits and I had to scrape the remainders off!

So buy quality like Dynamat or similar and you should be right.

[Dougal]

You need three layers.

The first layer sticks to the panels and deadens their vibration. Dynamat, roof flashing tape etc. This stops the noise at source. It doesn't need full coverage, just enough to take out the buzzing. It has to be stuck on in full contact.
The second layer is insulation, closed cell foam works best and provides a skin the remaining noise doesn't travel through while also isolating the metal underneath from the upholstery on top. It should be loose fit and needs to be continuous or at least overlap a lot at the joins.
The third layer is heavy carpet or vinyl to protect the insulation underneath and provide a deadening effect on top.

Do this and you'll get a huge benefit. But to do it properly requires opening up doors, pulling the dash out etc.

[Davo]

You need three layers.

The first layer sticks to the panels and deadens their vibration. Dynamat, roof flashing tape etc. This stops the noise at source. It doesn't need full coverage, just enough to take out the buzzing. It has to be stuck on in full contact.
The second layer is insulation, closed cell foam works best and provides a skin the remaining noise doesn't travel through while also isolating the metal underneath from the upholstery on top. It should be loose fit and needs to be continuous or at least overlap a lot at the joins.
The third layer is heavy carpet or vinyl to protect the insulation underneath and provide a deadening effect on top.

Do this and you'll get a huge benefit. But to do it properly requires opening up doors, pulling the dash out etc.

You must have one fancy car, putting carpet under the bonnet! :p

No, just kidding, that's good advice for inside and when I've done it, it's made a huge difference.

[DieselDan]

The stuff from Rare Spares should work a treat. Bear in mind that as its only thin, it will only absorb high frequency noise (short wavelength) such as injector tick and rattles etc, but that's only what the original stuff did.
As Ron said it will make a massive difference plugging up any little holes in the bulkhead.
If you want to stop more engine noise then you'll need to do something like Dougal said and start adding lots of heavy barrier type materials to block the noise coming in as its not practical to have several feet thicknesses of foam to absorb the lower frequency noises :o