What threads for insulation advice

[PeterK]

There are many threads covering sound insulation, but often with vastly differing views.

I have the original heavy insulation to go on the rear seats and have bought an insulation pad to go in the engine bay, but am struggling with the conflicting advice on what else I should do.

So, what are the 'best' threads to guide me on what to use, where ?
Thx
Peter

[911hillclimber]

Peter, the best thread I've seen recently is that of Darren65.
His orange 911 hot rod was lined throughout with pads that fitted well, not thick, and he was happy.

I lined the whole inside of my 911 in the hope most of the noise would be killed-off, but cannot really notice much difference!

His name crops up regularly in the forum, so easy to find and pm him.
He is most helpful.

[PeterK]

Thanks Graham
I know Darren and remember his hot rod build. I'll plough through the pages and also drop him a note (will probably be quicker ).
Peter

[Lightweight_911]

.
The main part of the sound deadening application in Darren's 'Mongrel' is on this page:

viewtopic.php?f=28&t=41415&p=435818&hil ... ng#p435818

[inaglasshouse]

But if you want quiet, I'm not sure I'd choose that particular car as role model.
Aesthetically I like what Darren did with the insulation and almost everything else, but I don't think refinement was a major goal?

[redrobin911]

HI - I did my 67S recently and followed some of the advice by Home made by Jeff on this forum. In my opinion the damping mat that most of use does not need to cover all the surfaces as all it does is stop panel vibration (which amplifies noise) so damping stops that and 50% or less coverage is all that's needed. To block noise you need mass loaded vinyl which is a multi-layer material which stops sound traveling through it. Problem is that MLV is really heavy so most use sparingly.

Have a look over Jeff videos and come to your own conculsion viewtopic.php?f=28&t=57418&hilit=home+built+by+jeff

also look here for some material that you could use https://www.deadening.co.uk/

[PeterK]

Thx all


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[PeterK]

Me again
Chatted by PM with Darren and then having rewatched Jeff's YouTube videos and scoured the various webpages of Sound Deadening Shop (thanks for the link Robin), it has reconfirmed my need for some damping mat. That's the simple part, and I intend to use 2mm Silentcoat and do the inside of the door skins, the floorpan (2 sides), the heel board and inner rear wheel arches. Coverage of up to 50% by area, but at least 25%. I have the original heavyweight material for the inside of the rear seat area and a replacement covering for inside the engine bay (none on the car when purchased)

Q1 - I think so, but is that enough places to stop drumming ?


Ideally I will then cover this with MLV, and DoDo Barrier seems to fit the need. However, it is 5Kg per square metre !
I've potentially got floor, tunnel, heel board, rear wheel arches, parcel shelf, under dash, front footwells, sills, doors and potentially the underside of the froot lid. That little lot is just under 7m2, and I'm baulking at adding 35Kg (and the £350 the MLV @ £24.99 per 1/2m2 sheet would cost). Lighter (isolator rather than MLV) alternatives are Silentcoat either in 10mm (£18.99/m2) or in 6mm (£14.99/m2).

It is a Targa, so on the plus side there's no roof to worry about covering, but also, no point in going to the max with deadening material if the roof is 'open' to the outside noise anyway.

Q2 please - what would you cover, and with what ?
Thx
Peter

[Bruce M]

I’ve used silentcoat, including on a steel bath at a fraction of the price of the official kit. Worked well

It stops the panels ringing like a bell, so it’s easy to go round the shell tapping with your finger to find the areas that “ring”. Add a patch of silentcoat and tap again. You’ll find one section is now damped but another part isn’t, so damp that next and repeat.

Personally, I think of the problem as in three parts. 1) the inside of the car shouldn’t be “reflective” or it will reverberate like a fully tiled bathroom. A thin RS style carpet can be enough to solve that problem. 2) The ringing panels, as above this can be damped using a material like silentcoat or dynamat. 3) noise transmission. Even with silentcoat & a thin carpet, noise from outside such as engine, gearbox, tyres etc will pass straight through with limited filtering (mostly upper frequencies). To solve that you need thick dense muffling material.

(3) is probably the worse and needs the heaviest solution.

[PeterK]

Thx.
It’s the 35kg for the ’heaviest solution’ that’s concerning me, so wondering if/where I can go lighter without too much increase in noise ingress.
Peter

[Gary71]

Proper noise insulation involves weight unfortunately. Also key to avoid airborne noise paths through grommets, gearshift etc to the engine bay. This high frequency stuff is rarely pleasant.

Bottom mine is it’s an early 911. They are noisy. That’s part of it, go too far (like I did!) and you can lose some of the character.

I had a double layer modern bulkhead material inside the engine bay and the same type again rammed under the parcel shelf.

Quieter? Yes, but it lost something and it won’t all be going back in again during the rebuild.

[PeterK]

Good point - maybe I need to go in a few more 911s and compare insulation to noise/ character

[redrobin911]

[quote
It stops the panels ringing like a bell, so it’s easy to go round the shell tapping with your finger to find the areas that “ring”. Add a patch of silentcoat and tap again. You’ll find one section is now damped but another part isn’t, so damp that next and repeat.
[/quote]

Yep that the way I did it as well, suprising how little daming material is needed to stop the panel resonance. Doors now close with a thud,