16 replies to this topic

[Deev]

Hello all...

 

At the risk of invoking forum wrath by reigniting an old debate, I'm after some advice on soundproofing my Mini. I've done a fair amount of research into the subject, both in the forums and elsewhere, but I've seen some wildly differing opinions as well as old posts with expired links to what to use, so was hoping to throw a few ideas around and find out the current thinking.

 

Firstly, I want to sound proof the bonnet and bulkhead. That should be the easy part, but I've noticed there are two types of insulation for the bonnet available - the "tailored" (i.e. four triangular pieces) felt mat, and the single piece insulation pad (47H9615 and CK975A on Mini Spares respectively). The tailored kit seems "neater", but is there any real benefit to the single piece pad? For the bulkhead, I'm planning on rewiring the car later in the year, so I'd guess a new pad at the back of under-bonnet behind the fusebox etc. would be good... or would it be better on the inside of the car behind the dash? Or both...?

 

Secondly I want to apply under-carpet sound proofing to address road noise. I recently had a new carpet fitted (bodyshop fitted it after doing some work on my floor) but I'm pretty sure it is now completely devoid of any sound insulation that may have existed with the OEM carpet, as I'm suffering from hellish drumming noise now... - There seems to be a wealth of options available, and whilst I don't want to spend an absolute fortune on this (read: Dynamat), I also don't want to scrimp on the cheap options. I'm also mindful of the weight I'm going to add to the car (although I am prepared to accept a slight weight gain in return for keeping my hearing...).

 

From what I can see, Silent Coat seems to be the best compromise of cost and performance, but I'm a little confused as to whether this needs to be paired with something else? I'm thinking sticking Silent Coat to the floor for vibration reduction, and then something else on top to add additional soundproofing? And if the Silent Coat is for vibration reduction, I don't need total coverage of the floor, right? f I'm adding something on top, would 2mm Silent Coat be preferable to 4mm? Or in fact do you think Silent Coat would suffice on its own? I've read about adding closed cell foam although the stuff I've seen seems pretty thick.

 

Another option I considered was to get the soundproofing kit from Mini Spares (MS91) as I'm wanting the bonnet and bulkhead pieces anyway, and then using the floor section pieces on top of the Silent Coat?

 

You can see why I'm confused...

Can of worms opened. All suggestions gratefully received!

 

Cheers,

 

Dave.

 

[neal]

You mentioned a drumming noise in your car.....

 

A drum (not that I am musically minded) has a rigid frame (which is very much like a lot of the taught rigid small panels in your car) and a thin skin which flexes and resonates very much like your floor pan, roof and other large surface areas in your car.

 

If you were to add bitumen strips to the large thin panels, this will thicken the panel up, reduce flexing and generally stiffen up these areas including rear quarter panels, inner door skin, inside the companion bins, you name I did it.

I also bought some real cheap carpet underlay from my local shop, it is dark grey, about 6mm thick dense poly foam, very cheap and then stuck it down wherever I could using a good contact adhesive all over.

 

I get no drumming noises and many have commented on how quite it is, this now enables me to hear my twin hs4 snorting away while the Barry White tone of the exhaust reminds me of the song

 

https://www.google.c...KHefpBMwQri4IJw

 

or maybe

 

https://www.google.c...KHQ-ODwgQri4IJA

 

Either way, Enjoy!

[Deev]

I'd like to avoid bitumen strips, flashing tape and the like, as I've read that, whilst it's effective and much cheaper than other options, the bitumen is apparently quite... odorous...

 

I like the idea of the cheap underlay, although I'd be afraid of how much that stuff can hold moisture, and I'm not sure I'd want wet underlay glued to my floor as we all know how much Mini steel likes turning into brown dust... I think that's why closed cell foam is recommended as it doesn't hold moisture...

 

I dream of the day my Mini is quiet enough for me to be able to hear Barry's dulcit tones!

[Laurie]

I too when my bonnet is finished am thinking of adding sound deadening to it, I was all this time considering only the 4 tailored felt triangles tbbh. I hadn't considered even anything else.
As you mentioned Mini steel loves the brown dust, so I'm watching this thread with interest as to what you choose.

Have you got a link (save me googling) for the closed cell foam - that sounds ideal!

[greenmini1275]

I've got closed cell foam. It's a pain in the ass to cut and fit but it does do a bit of a job, but I've only fitted 5mm, thicker might do a better job. I've got it on tne inside of my bulkhead, I want to fit a pad to tne inside of the engine Bay Area. I need some anti-vibration stuff though. I'm thinking of using some kind of Spray on sound dampener as well for things like the inside of doors, roof, under bonnet and boot floor, probably pretty much everywhere else as well.

[neal]

I'd like to avoid bitumen strips, flashing tape and the like, as I've read that, whilst it's effective and much cheaper than other options, the bitumen is apparently quite... odorous...

 

I like the idea of the cheap underlay, although I'd be afraid of how much that stuff can hold moisture, and I'm not sure I'd want wet underlay glued to my floor as we all know how much Mini steel likes turning into brown dust... I think that's why closed cell foam is recommended as it doesn't hold moisture...

 

I dream of the day my Mini is quiet enough for me to be able to hear Barry's dulcit tones!

The stuff that I used is closed cell foam, does not hold moisture water etc

[neal]

 

I'd like to avoid bitumen strips, flashing tape and the like, as I've read that, whilst it's effective and much cheaper than other options, the bitumen is apparently quite... odorous...

 

I like the idea of the cheap underlay, although I'd be afraid of how much that stuff can hold moisture, and I'm not sure I'd want wet underlay glued to my floor as we all know how much Mini steel likes turning into brown dust... I think that's why closed cell foam is recommended as it doesn't hold moisture...

 

I dream of the day my Mini is quiet enough for me to be able to hear Barry's dulcit tones!

The stuff that I used is closed cell foam, does not hold moisture water etc

 

I can't smell the bitumen in my car and I've used quite a bit, mind you its all under the closed cell foam underlay and carpet.

[minimans]

3M make a bitumen Type pad that is self adhesive and a very good product Takes the drum out completely. Just stick to every flat surface especially the roof! that's where most of the druming noise comes from not the floor which is pretty rigid. I try to avoid sticking underlay down if I can even if you use closed cell foam the moisture  will still sit on the floor and it's easier to remove in a few minutes and dry out   

[greenmini1275]

Strips of self adhesive Velcro will keep any loose sound deadening/carpet in place and is easy to lift everything out for a regular cleaning.

[Dusky]

I used some sticky panel 'heavening' stuff ( I know this is the wrong word, but im awake 26 hours now and can't think too straight )

Added it on the underside of the bonnet, firewall(bulkhead), rear parcel shelf, rear passenger panel, boot floor and boot lid.

All in all I added 800-1000gram weight. But the mini felt a lot more rigid and was a lot more silent. 
I then added sound absorbing foam ( Im a musician and get it free) behind the dash,under the bonnet , a small patch in the boot, and a bit in the rear companion bins.

Dare I say its almost as silent as my girlfriends Ka (2011)?

[pete l]

https://www.sounddeadenershowdown.com/

[minimadman1]

I used silent coat off eBay very good stuff got about 30 sheets for £40 I put 6 on the roof before the roof lining and it's got rid of that tin can feel. Very impressed it so far

[Deev]

Not sure I can be bothered to remove the headlining *yet* as it's a bit of a faff of a job, but will probably go with Silent Coat for the floor... maybe some inside the doors too...

 

Am I right in my assumption that you don't need complete coverage of the floor/panel with Silent Coat? As it's more a weightening solution, and it's only the sound deadening stuff you need complete coverage for?

[tiger99]

You really do need the bitumen pads as none of the other products will stop the drumming. The original problem with bitumen was that it was originally applied to bare metal, and we all know what happens if it cracks.... When applied over your properly painted surfaces, that is not a problem. It it does smell, paint over it with some primer-sealer  and topcoat to seal the smell in, but usually bitumen is ok.

 

The other products, heavy felt closely fitted, foam with heavy top skin (sometimes lead, but there are alternatives), etc, are all good at what they do, and whichever combination you choose goes over the top of the bitumen.

 

Most foam and felt type insulation materials are also of some use as thermal insulation, so get as much coverage as possible, and it will help keep you warm in winter.

 

One of my Minis had insulation on both sides of the upper bulkhead and I recommend that, with great attention to filling the huge hole around the speedo area (on many cars) by fitting not only a couple of layers of insulation but also a removable sheet metal cover which may be split to fit around the cables. It rather depends on whether there is carburettor or air filter intrusion into that area.

 

The bonnet is likely to be most practicable with four separate pieces, and a single overall thin sheet. Some people inject the stiffners, and other bits of the car, such as the seat crossmember, with structural foam, which stiffens things up nicely and definitely reduces noise, for not much weight.

 

You could work at it almost for ever, attending to details here and there, but start with the basics, which may be all that you need.

[Laurie]

I bought some closed cell foam today, on a roll from a local shop I didnt even know existed until last night!
Problem is, its not sticky back.
How do I get around this? As Im sure most glues would melt the foam / ruin the bonnet (its 6mm foam - 1 m x 1.5m)