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

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.

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

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

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 :)

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

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.

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:
...

i think there is a tipping point where you can insulate yourself too much and disconnect from the driving experience in a negative way yes. I wouldn't want to go any further than i have for that very reason myself.

When you have 2 and one is noisier than the other, it does drive a certain amount of curiosity. Aside from soundproofing materials, it should also be mentioned about the impact a quiet set of tyres can have.

absolutely :) . As for tyres, best I know of are those dunlop blue response ones. I think its about 67 or 68db is the figuire they quote - lowest I can find, and pretty reasonable price too. fantastic proposition. Any better recommendations anyone has I'd be interested to hear, but cost vs refinement I can't see a better game in town

Cant help there. I am running the same dunlop blue responses as well. Marvellous tyres, transformed the road noise for the better

We purchased a new memory foam mattress then didn't like it.
As no one else wanted it I cut it up to get rid of it but I struck on the idea of using the base material, not the rather thin memory foam to insulate the boot area of my V6
It certainly made a difference. I first removed the boot liners then tailored the thick material into place before re fitting the liners.

I intend doing a similar job on my XF as earlier this year the missus commented that it was much noisier than the 75 when travelling with the rear seat folded down.

If you do want foam, carpet underlay (e.g. Cloud 9 Nimbus) is probably the cheapest way to do it.

your car is quiet.... as you constantly say in these type of threads, good for you..... a LOT of ours aren't.....

Including my cdti.

Logically the debate about noise has to start from some sort of datum line. So whose car is going to be used as the base to work from? And what sort/amount/location of sound proofing does it have fitted?

Just trying to point out that noise is, like beauty, in the ear of the beholder (rather than the eye) innit... :Snow:
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My case is that the datum line was my old Rover 420sdi. I got the 75 and was delighted with it.......for 13 years. Then got the second one, and it was noticably noisier so i simply set about trying to make it as quiet as the first.

I would say i have taken it 95% of the way and am very happy also with the second car now, but there is still something, and i suspect it to be the doors.

As i had material left over from car 2, i didnt see any harm on using it around the boot on car 1, but as I said it didnt make much difference that time. That is probably because that car does have 3 silencers so there wasnt so much boom from the back box to deaden in the first place.

I have reached the point that car 2 is a little but noisier than car 1, but not really noisy enough for me to make the effort to take all the door panels off again to put sound deadener in, although at some point i may need to replace the lock motor, so if i do i will give it a try.

I guess what i am saying is that for 13 years I agreed with you. If i had only ever driven the second car i would have agreed with you as well. Its only because i had an exceptionally quiet one, then one not so much that i got on to this track, and now have what i think are 2 quiet ones.

Like Jim's case, who would ever inagine a brand new Jag would be noisy? Well if they have had a quiet 75 previous to it then they would, and some of us just want a quiet life and a nagging curiousity to know why things sound different.

I have been in 3 cars of various late models recently with distinctly noisy wheel bearings, and sat there thinking of the drivers, "cant you hear that racket?" But they were oblivious to it, so again as you say sound is in the ear of the beholder. Agreed.

It's more likely the tyres were the problem, rather than a wheel bearing.

The OP has a 2005 built 75 and would therefore will be fitted with a thinner cheaper carpet.

The biggest improvement you can make to a later model 75 or ZT is to fit a carpet from a early Cowley built 75.

The Cowley 75's were fitted with a much thicker carpet and the foam bonded to the carpet was thicker in places.

Dave T

I am pleased to see someone else posting who thinks the CDT's are noisy. I was out walking my dog the other day and a car came up behind me making a fair old noise. When it went past and stopped I saw why. It was a BMW 320d. Now I have driven one of those and from the inside it was as quiet as my 523i, (well nearly!). So it must be a question of soundproofing with ours.

Many thanks for all the messages and ideas sent in this thread! Yes, I had overlooked the carpet. The carpet in mine is really a very nasty, thinnish, synthetic and nowhere near has the feel of, and quality, that was on my year 2000 V6. Perhaps in time I will grow accustomed to the harshness of the CDTi - but how I miss the cossetting luxury of the Cowley car.....ED

The door mirrors were noisy on my car, so I swapped the skull cap type for some bullets, they can still be heard, but only if you listen for them...

My friends recording studio has egg crates stuck on one wall to deaden sound reflection. ? :Snow:
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Sound proofing
 

I have a 2004 diesel Connoisseur, 'Elgar'. It has 'fork' alloy wheels and Pirelli tyres. The engine is quite well muted, but could be quieter. The wind noise is quite noticeable. The worst noise is the noise of the tyres over most surfaces. The car also has various rattles and buzzzes from places such as doors and somewhere around the dash. There is also a whining sound which comes from the engine and is most noticeable at low speeds. I have no idea what this whining sound is, but it makes the car sound 'cheap'. The driver's door has a cheap-sounding hollow sound when it is closed. I would like to get some sound deadening for that door at least. However, despite all this, I get a lot of pleasure from owning and driving a Rover.

If you have forked alloys I guess they are the larger diameter ones. When i first got my blue auto it had Meteors with some kind of low profile tyres and i thought I had 4 flat tyres at times. I switched to 15” crowns as soon as I could in order to restore the silent running mode.

The whining noise comes from the HP fuel pump causing a resonating sound along the rigid stainless steel fuel pipe.


I wonder if the car could need a 4 wheel alignment carried out??, also has there been any work undertaken on the drivers side door, this could be a cause of the rattles and clunk sounds perhaps :shrug:

My front passenger door handle is slightly loose and makes the door sound 'tinny' when it is shut. I have read about door handle removal and put it in the 'nope' category. Mike be worth seeing if it the cause of your door sounding cheap. That or the striker needing adjustment maybe.

Madness but...
 

I've spent £75 on sound deadening pads over the last few weeks, I want my ZT as quiet as my 75 is. I've done the whole bulkhead and redone the floors and I've coated the tunnel from front to back. It's very quiet now in the cabin with the V6 running, the scuttle isn't yet fitted and I've not put the pads under the bonnet as yet, I'm putting some pads on the underside of the bonnet and a double felt pad like the 75 has. It's overkill but who cares? I have a very quiet ZT and It will make people think when they don't hear it!

Thank you.
 

A few years ago the door was damaged and was replaced with a used door. Thank you.

I wonder if the garage, I assume it was a garage that carried out the replacement, omitted the internal door foam, or damaged it in some way?


Just a thought of course Andrew, I may well be way off the mark, but it might be worth having a peek at what is going on behind the door card.


Alf

Morning Andrew, hoping you and the family are keeping well.

I know the story behind the drivers door replacement on your car, and the probably the cause of the rattles ;)

Your door was sourced for the painter via a very kind and generous offer of a ZT door from Gary and Lydia in York.

Knowing the varying standards of the painter's workmanship which were in the main erring on the low side putting it politely, I'd say when he was transferring the lock door handles and trim from your original door, there would have been less care taken than repainting Edgar's coach line.

Once the restrictions are relaxed, you might wish to pop over and I'll take a look for you, I wouldn't be surprised if the door liner hasn't been damaged or even not refitted at the least.


Brian :D

Thank you. M.

How did you do the whole bulkhead ?

Pete.

Like this.
 

Dashboard and heater out to do the job, I wanted to find all the water leaks so it was just an idea I've had for awhile. The cabin is now very quiet but I'm not finished yet as I'm doing some more in other places.