Targeted sound deadening

[Retroanaconda]

I have a nice big box of Dynamat and a bog standard 90 to fit it to - I would be interested to hear peoples views on the best places to target it’s application. It is a vibration dampener rather than a sound blocker, so I need to focus on panels that resonate and cause or amplify noise.

Preciously I have used it on the rear wheel arches, seatbox, floors and bulkhead. I now have the wright off road matting in the front so not much benefit in fitting it there I don’t think, my thoughts are that all three doors and the rear wheel arches would be the best start point. The roof too but haven’t got enough to do that in this phase. I already have dampening fitted to the upper hard top sides.

So I am thinking to start with:

Front doors x 2   
Rear door   
Rear wheel arches and tub sides   
Bonnet

I also have a box of closed cell foam which I will fit on top of the Dynamat in non-loadbay surface areas like the inside of the doors and the underside of the bonnet - reckon it can’t do any harm.

I did all this many years ago and it worked well, but interested to hear if there any pitfalls or things to be aware of, or indeed if I could target it better. 

[Snagger]

A little pad on the inside of each door skin makes a difference, but the biggest bang for your buck will be the flat panels of the roof sections and the hard top sides.  The tub wheel arches are worth attention.  The tub floor is best done with a thick rubber mat like stable matting, as it’ll be heavier and more resilient.  Doing the bonnet reduces external noise but won’t make a jot of difference inside the vehicle (I learned that the expensive way).

[Bowie69]

Also, no need to plaster everything, you get 90% of the benefit with ~30% coverage.

They youtubers seem to like to slap it everywhere, but then I suppose they are sponsored....

[Snagger]

Yep, even see 100% coverage on the Retropower videos.  That adds weight, but past 50% cover, it has diminishing returns on its effectiveness.

[Retroanaconda]

Thanks. I already have the rear hard top sides done (albeit with builders flashing), and I’ve got a bit of thick rubber matting on the floor - a bit of 3/4” quarry crusher conveyor belt.

The wheel arches will be the first bits to get done. I will cover 100% of those as it will create a smooth level surface to carpet over, but we’ll see how I get in with the doors.

I’m happy for the bonnet to only be a benefit outside the vehicle - soundproofing matters there too!

[Wreckrunner]

I found a huge difference when I added Killmat sound deadening sheets to the bulkhead and footwells of both my Series IIA and my 93 Defender 90. I also did both front doors and the seat box. I did it not so much for sound reduction, but for heat dissipation here in Southern California!

[ThreePointFive]

15 hours ago, Wreckrunner said:

I found a huge difference when I added Killmat sound deadening sheets to the bulkhead and footwells of both my Series IIA and my 93 Defender 90. I also did both front doors and the seat box. I did it not so much for sound reduction, but for heat dissipation here in Southern California!

That raises an interesting point as I can feel the heat through my bulkhead, I need to find something that will work on the engine side.

For sound deadening I did go full-youtuber in the roof and sides which seemed to have stopped any resonance. I have an Exmoor trim load mat/sound deadening thing which I have never really given a second thought so must be doing something (don't buy one, the fit and finish is awful). I did the doors as fully as you could, if nothing else they give them more weight and a satisfying thunk.

The biggest change was when I plastered the transmission tunnel, my gearbox was screaming and yet it quietened it down with only one layer. The issue is now finding a suitable cover, but that's solvable.

I know this doesn't answer the exam question as I did the full-coverage approach but it worked...

[Snagger]

I found no discernible difference in cab noise between having just the Wright Off Road matting and adding full sound proofing to the entire front of the bulkhead and footwell tops, inner wings and underside of the bonnet.  I did find a difference adding some high density foam under the gear box tunnel cover and centre of the seat base, even though they had the WOR kit - the kit is a bit thin in those places and benefits from additions.

[Retroanaconda]

My car had factory soundproofing on the engine bay side of the bulkhead, which I didn’t reapply but perhaps should have done. That combined with stuff I put on the cabin side plus all the factory CSW stuff made it pretty quiet inside for a Tdi before I rebuilt it.

It’s noisier now than it was and I’d like to address that, but I’m not sure I’ll ever get it as quiet as it was. Doing the rear tub etc. will hopefully help and my hope is that the WOR kit has done what the old factory soundproofing/carpets used to do - but with a more resilient finish.

This was the stuff on the bulkhead. I was in a rush rebuilding it and didn’t replace it, and of course now it will be a ball-ache to do with the car reassembled 

[Ed Poore]

On 6/3/2022 at 8:49 AM, Retroanaconda said:

thick rubber matting on the floor - a bit of 3/4” quarry crusher conveyor belt.

Is it stuck down because the floor may well still vibrate underneath it. I had thick rubber on the 110 but then put some silent coat on it and that was more effective as it was adhesive lined so stuck down to it.

[simonr]

I used 1/2" Conveyor in the load area floor & wheel boxes.  You can pick up used conveyor for very little.

It was loose on the floor, but a good fit.  I glued it in place on the wheel boxes, just to stop it falling off.  The result was a significant difference in noise.  The vehicle already had an OE cover on the seat box, otherwise I would have bought the WOR matting system.

On my next vehicle, I just bought WOR - and the difference on a poverty spec Td5 with no insulation whatsoever was like night & day!  Deafening at 50mph to being able to hold a quiet conversation at 70!

[Retroanaconda]

I was lucky and found the conveyor belt in a quarry, just had to cut an inch off it to fit the load space. It’s not stuck down, I may need to replace the floor in the future so not too keen to do so yet but if I ever do that I can glue it then 

[simonr]

This place will supply cut to size:

https://mesinternational.co.uk/product/ex-demo-rubber-conveyor-belt

And, without the fabric weave, just rubber:

https://mesinternational.co.uk/product/heavy-duty-black-sheet

It's more than I paid, but the company I used no longer exists.  It's a lot cheaper than buying even a horrible, thin rubber mat!

[chuff]

Doing the roof makes a huge difference. 

[rusty_wingnut]

James, one thing I've found recently is that the infill panels around the rear lights need to sealed properly, I left one loose in the 110 and the noise was bad. Definitely worth getting those snug against the body. make sure you've got your foam infill around the gear lever and tunnel.

 

I removed the noise killer in the roof of the 110 as it wasn't effective as the replacement headlining. New headlining has got a foam backed material over the board and soaks up noise nicely.

[Thug]

I recently did the rear of my 90 (incl roof) and it has made a discernible difference. Also put a couple pieces of material in each front door.

Now considering under the bonnet but am debating whether there will be any effectiveness sitting in the cab,

 

 

 

[tuko]

I enjoyed reading this thread with the many different points. I think it's where you're starting from which will give the most bang for the buck or lack of. 

On the x-mod 3 door Defender that I have I went full or maybe beyond YouTuber with both Silent Coat pads and Armaflex 13mm close cell insulation.

Before starting the process of covering everything, I filled the 60-70 redundant mounting holes with body sealant, then when dried covered with aluminium tape.

Silent Coat, I went through 7 large boxes covering literally everything in my path. Bulkhead, tunnel cover, floor panels, sweatbox including the battery box and tool box, the doors, rooftop, side panels, wheel boxes and rear floor. 

Then I applied Armaflex close cell insulation foam (13mm) to nearly everything paying attention to the rear of the 110. In total I went through 9 square meters of the stuff. 

For me starting from nothing then going to a nearly completely dampened and insulated Defender the difference has gone from deafening to a comfortable cruiser. 

I think any attempt is going to be beneficial, to what degree depends on your ears. Just go for it. 😉