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-   -   Improving SOUNDPROOFING (https://www.the75andztclub.co.uk/forum/showthread.php?t=232627)

Edward Huggins 11th December 2015 18:04

Improving SOUNDPROOFING
 
I have a very, very late build Rover 75 CDTi. It has full wheel arch liners, underbonnet and bulkhead soundproofing - and full boot carpeting. In fact the carpet over the spare wheel is twice as thick as that on my (just sold and much missed!) Cowley V6. I have added an engine undertray (not present when I bought the car) and some thick rubber mats front and rear. I have noticed that there is no sound insulation under the rear parcel shelf, but there is foam at the front of it. In terms of improving the sound deadening I had thought of adding some foam around the (full size) spare wheel and some black felt in the door bins. Short of adding deadening to the inside of the doors, I just wondered if Members might suggest any other insulation areas?? EDhttp://www.the75andztclub.co.uk/foru...cons/icon5.gif

Jakg 11th December 2015 18:28

What noise are you trying to isolate?

I've insulated my car a lot (mainly for speakers, not done for NVH reasons) and I can't say it's made much of a difference.

In my case, the spare wheel insulation made little difference - I suspect the rear seats act like giant sound absorbers as they completely seal a large part of the area between the boot and cabin.

EDIT - Also I don't think felt is the sort of product you want to be using. You need proper products for the job.

awvc1 11th December 2015 18:49

i have a CDT and I did a whole load of soundproofing for the stereo install. AS this is about as noisy an engine derivative as you can get, my successes may be of interest to you.

Just by using dynamat or eqivalent on the inner face of the outer door skin, the amount of cabin noise was reduced unbelievably, without needing sound proofing materials to deal with the outside noise - it seems the resonance in the panels once deadened is a real contributor. Whether you care about your stereo or not, the dynamat type stuff (I used Silent Coat 4mm) is fantastic and left my noisy Post Project Drive CDT quieter than my wife's Pre Project Drive V6. its like driving the submarine out of Red October.....

Look in the ice for my 'mdf rings' thread if you are interested in pics and tips on how i did that - remember, its not relevant in your case to the stereo, you get a win on general soundproofing with this .

Hope this helps

David Lawrence 11th December 2015 18:50

Foil backed bitumastic type deadening material is good for around the boot. I took out all the boot liners and coated the inner rear wings, and all around the boot and wheel well, then used some stuff called dodomat to double the padding on top of the bitumastic one.

Deadened the drumming from the exhaust.

In addition i put a layer of the dodomat which is heat and fire resistant on the bulkhead.

Made a difference in my 2002 car, but made no difference on my 2001 car, so i think you are just going to have to try it and see.

awvc1 11th December 2015 18:53

Quote:

Originally Posted by David Lawrence (Post 2167116)
Foil backed bitumastic type deadening material is good for around the boot. I took out all the boot liners and coated the inner rear wings, and all around the boot and wheel well, then used some stuff called dodomat to double the padding on top of the bitumastic one.

Deadened the drumming from the exhaust.

In addition i put a layer of the dodomat which is heat and fire resistant on the bulkhead.

Made a difference in my 2002 car, but made no difference on my 2001 car, so i think you are just going to have to try it and see.

its good advise David - I still think the biggest wins is in the cabin area i.e. the doors he doesn't really want to do - but it isn't such a horrid job really, and well worth it, as it is the lowest hanging fruit. I've never bothered with my boot, as the stock sound deadening is pretty comprehensive, and the sound insulation in the carpet in the boot is pretty good too

David Lawrence 11th December 2015 18:53

Quote:

Originally Posted by awvc1 (Post 2167114)
i have a CDT and I did a whole load of soundproofing for the stereo install. AS this is about as noisy an engine derivative as you can get, my successes may be of interest to you.

Just by using dynamat or eqivalent on the inner face of the outer door skin, the amount of cabin noise was reduced unbelievably, without needing sound proofing materials to deal with the outside noise - it seems the resonance in the panels once deadened is a real contributor. Whether you care about your stereo or not, the dynamat type stuff (I used Silent Coat 4mm) is fantastic and left my noisy Post Project Drive CDT quieter than my wife's Pre Project Drive V6. its like driving the submarine out of Red October.....

Look in the ice for my 'mdf rings' thread if you are interested in pics and tips on how i did that - remember, its not relevant in your case to the stereo, you get a win on general soundproofing with this .

Hope this helps

Did you do the doors?

On my 2001 cdt it had an extra exhaust silencer which is probably why i didnt see much improvement compared with the 2002 that didnt have it

awvc1 11th December 2015 18:57

Quote:

Originally Posted by David Lawrence (Post 2167121)
Did you do the doors?

On my 2001 cdt it had an extra exhaust silencer which is probably why i didnt see much improvement compared with the 2002 that didnt have it

that's what i focussed on - the resonance induced in the doors is most of the cabin noise I reckon. If you did that, and the roof panels (which I ran out of deadening for by the time i was done) you'd have a car quieter than the quietest cowley builds. i know because i have :)

David Lawrence 11th December 2015 19:00

Quote:

Originally Posted by awvc1 (Post 2167125)
that's what i focussed on - the resonance induced in the doors is most of the cabin noise I reckon. If you did that, and the roof panels (which I ran out of deadening for by the time i was done) you'd have a car quieter than the quietest cowley builds. i know because i have :)

Roughly how much dynamat or silent coat did you use in the doors? I assume you didnt use the dodmat type foam in there?

awvc1 11th December 2015 19:07

You need a pack of about 12 to do all 4 doors comfortably I'd say, and that includes doing the inner face of the outer skin, and fixing some to the inner face of the inner skin just below the OEM soundproofing foam - I used it to reduce inner resonance and plug the holes in the door structure to improve the bass response of the speakers by making the door more an enclosed and sealed space.

I didn't touch dodo stuff on the doors - whilst you have all the space in the world on the inner door sides, putting dodo foam under the door card would make it a real tight fit and I didn't go down that road. didn't seem to need it in my view, but I guess YMMV.

James.uk 11th December 2015 19:28

I don't see a problem really, my car (75) is far from noisy as is? :Snow:

It is def one of the quietest cars I ever owned?

I can hear the engine if I listen for it, which is usefull, and I can hear the tyres on some road surfaces, which is also good as it's informative.

Perfik innit..... :Snow:
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