Thread: Sound Deadening

In general I have been trying to get rid of noise such as road, tyre, rain, engine etc. dynamat has def helped and also the under bonnet foam with foil. The stereo sound better and hands free calls are much easier.
Yes it's a lot of money but I value the car being quieter as I have to make a lot of work phone calls whilst driving.
Previously the sound of a rock being flung up by a rear tyre under the guard was like a cracking noise of a large rock hitting the windscreen which scared the crap out of you.
Now the issue is gone.

So the general chattering noise under the bonnet tends to be injector pump and not the injectors themselves???

It's a TD5.

Originally Posted by Blade74

In general I have been trying to get rid of noise such as road, tyre, rain, engine etc. dynamat has def helped and also the under bonnet foam with foil. The stereo sound better and hands free calls are much easier.
Yes it's a lot of money but I value the car being quieter as I have to make a lot of work phone calls whilst driving.
Previously the sound of a rock being flung up by a rear tyre under the guard was like a cracking noise of a large rock hitting the windscreen which scared the crap out of you.
Now the issue is gone.

My point was, dynamatt is a poor choice for that purpose. Dynamatt is a deadener, you attach a piece to each buzzing panel to damp out the vibrations. Then you use an insulating layer (closed cell EVA foam, felt etc) to actually stop the noise.
EVA foam is a lot cheaper, a far better noise blocker and a better thermal insulator than dynamatt. The main benefactors from full-cover dynamatt are those selling it.

Originally Posted by Blade74

So the general chattering noise under the bonnet tends to be injector pump and not the injectors themselves???

IN general yeah about 50% of the noise can be the injection pump. But not really on the TD5 as each injector is built into the head.

I understand its a deadener.... Hence I also have wave bar which blocks noise...
But to be truthful dynamat has worked well so far.

I understand in sound there are the following.
Deadeners
Blockers
Absorbers
Diffusers

Foam is more an absorber...

The item I have under the bonnet is dynamat hood liner which is an absorber.

The Wave Bar which will go over the dynamat is used to block noise transfer in commercial applications all the time.

Originally Posted by Blade74

I understand its a deadener.... Hence I also have wave bar which blocks noise...
But to be truthful dynamat has worked well so far.

I understand in sound there are the following.
Deadeners
Blockers
Absorbers
Diffusers

Foam is more an absorber...

The item I have under the bonnet is dynamat hood liner which is an absorber.

The Wave Bar which will go over the dynamat is used to block noise transfer in commercial applications all the time.

Closed cell foam is a blocker as well. Much of the absorption comes from the air gap between the deadened panels, the foam and the foam and top covers.

If you want to cover everything in deadener, use cheaper roof flashing tape which does exactly the same job. It is ludicrous to use $800 of dynamatt for such a job.

Dougal, could you please give us an example of how dynamat should be used in a defender.
What i mean is where the best places would be to put it, the typical required size of the patch to achieve deadening, best places on desired panels to put the patches....

From reading what you've posted so far i'm thinking the following for my 90

A couple of 30cmx30cm patches on the rear floor under the rubber mats

The same on the roof under the headliner, 2 patches, then some EVA foam between the headliner and roof

One patch on each of the foot wells

Two strips on the sides of the seat boxes

Any other ideas welcome.....

It sounds like you have the right idea. If you're using Dynamat as a deadener it should be applied to thin panels where the surface area is large between solid points (folds, mounting, welds, etc). You're trying to stop those panels from vibrating like a Rolf Harris style wobble board. You can significantly reduce the wobble board effect without making the whole panel thicker. Just add weight to the centre (like a piece of dynamat).

That's for a sound deadener at least. Heat and other sound reduction layers (absorb and barrier) have different theories. For example:

Heat = foil.
Absorb = foam.
Barrier = heavy vinyl.

Originally Posted by bapo

Dougal, could you please give us an example of how dynamat should be used in a defender.
What i mean is where the best places would be to put it, the typical required size of the patch to achieve deadening, best places on desired panels to put the patches....

From reading what you've posted so far i'm thinking the following for my 90

A couple of 30cmx30cm patches on the rear floor under the rubber mats

The same on the roof under the headliner, 2 patches, then some EVA foam between the headliner and roof

One patch on each of the foot wells

Two strips on the sides of the seat boxes

Any other ideas welcome.....

I don't have a defender, but you're on the right track as Judo said. Target the biggest and flattest panels first (I'd expect those to be doors, roof and floors). Use a convenient sized patch in the middle of each panel. The idea is to stop the panels buzzing and ringing. You will hear the difference tapping a panel from before to after.

You'll get the best results from covering everything in EVA foam. More thinner layers are better than fewer thicker layers for both installation flexibility and noise reduction.