Menu
What's new
By:
Advanced search...

Soundproofing - Many guides inside

It's just a bit annoying that the stuff you used on the rear wheel wells was unavailable when I did the job earlier , so I'm not sure if the 1mm MLV/6mm foam/1mm MLV laminate I used instead is as good and whether,as a result, the reduction is as large as you experienced. What's left is a mild roar from the rear - similar to remote wind noise - roughly as loud as the surface noise from the front. Is this about the same as you have? Is it worth ripping out again and replacing it with what you used? As an experiment, I laid a carpet rug over various areas including the full rear seat/shelf and inside the boot right up to the parcel shelf but it didn't make any difference.
Out of interest, I test drove a 2011 facelift Accord with the acoustic windsceen, refined sound deadening etc. and the same types of road noise and rumble were present but reduced by around 20%.
 
Ah I see. The issue is that it's all subjective; even with a fully calibrated dB meter you might have the same "loudness" but one sounds quieter due to the frequencies involved. They pour a lot of r&d into "sound quality" after they meet the loudness targets.

Generally speaking however; more mass will do a better job at blocking noise but it's a pain to do those rear arches and I don't think the difference will be all that dramatic. One thing I did that I never mentioned was unzipping the seat backs and putting the MLV in there too. After all the seats are just foam with a metal backing that's full of holes.

The next step for me is to apply thinsulate to the doors and vertical surfaces in the boot. The idea being that I've done all I can blocking the noise. The little that remains should now be absorbed as much as possible as the one side effect of mlv is that it's very reflective. So once it gets in it reverberates. The deader the space the less annoying it sounds, which leads to another interesting fact; glass is a *******. A lot of road noise from the rear will bounce right off the rear glass and then off the windscreen into your face as some sort of annoying noise periscope - hence the thinsulate under the parcel shelf.

If you want an extreme example, the people on talk audio tend to go absolutely mental with soundproofing; http://www.talkaudio.co.uk/ipb/index.php/topic/371991-honda-accord-sq-family-car/

The issue I have with these is that you're really eking out the last 5% of what the vehicle structure is capable of but spending loads in the process.
 
Yes, I think the Accord tourer in that blog is WAY OTT. I think that with the factory wheel arch insulator covered with my laminate of 1mm MLV/ 6mmCCF/1mm MLV and 2mm MLV under all the carpet mats, I'll stop there. I'd hate to pull out that arch liner again and replace the laminate with the stuff you used and find no real difference. Of further interest, in addition to the 2011 Accord EX, I also tried an Insignia ( a bit less rear road noise ) and a 5 yr. old Passat which was maybe on a par with the 2011 Accord.
 
Funny you should mention the Insignia - I found it to be much worse, but it was quite a worn demonstrator car; I don't think the 18" wheels as standard helped either! From my experience, if you want quiet then BMW is king for somewhat-affordable used cars. The 3 series is deathly silent from the back with only a tiny grumble from the front.

I've found that whilst I like my accord very much; Japanese cars are some of the noisiest, specifically Toyotas. They mustn't test much on our roads :D

Ooh I dug up that presentation around different approaches to noise too, heavy MLV vs Absorption and a hybrid design;

http://www.sae.org/events/nvc/workshops/2007pafumi2.pdf

http://www.sae.org/events/nvc/workshops/2007pafumi3.pdf

You should know as well the accord does use an early pillar-separator approach, there are foam blocks stuffed in the A, B and C pillar hollow cavities to stop noise from resonating up inside the body. But they are between welded sheets of metal so can't be beefed up.
 
Yes, even my E46 330 convertible has very low noise from the rear. I've tried the later 3 series on runflats - horrible ride and tramlining - quiet though. Talking about testing on our roads, Honda engineers from Japan came to Europe and liaised with German and British Honda engineers to develop the sound deadening package for the 2011 Accord but the updates centred mostly on the front end - bulkhead, screen etc. although in the brochure they boast of a floating substructure to isolate NVH. The 2003-2008 Accord, for me, is the best all-around package,but I'm getting a real bee in my bonnet with the rear road noise. I'm sorely tempted to pull out my arch MLV/CCF/MLV sandwich and try what you used, although being a pessimist I can't see it being a night and day difference. Doing a comparo, the stuff you used has 1 layer of EPDM at 1.2mm thick as a blocker which is very similar to 1mm MLV except the stuff I used has 2 layers of this and the absorber layer of yours is 10mm felt compared to 6mm CCF on mine. Probably even?
 
I measured the barrier laminate more accurately with a micrometer this morning. Overall it's 7.5mm thick with the top and bottom MLV layers 1.3mm each. Therefore, if you add both MLV layer together you get 2.6mm which is 1 lb./ft. which is 5 kg./sq.metre. The CCF ends up being 4.9 mm thick. According to this site http://www.sounddeadenershowdown.com/ the CCF does not absorb any sound in the audible frequency range at that thickness and any other absorber type such as felt or thinsulate degrades in performance if compressed so in a tight area such as the rear arch by the seat side bolster, what I've used may be the best bet and it may be worth loosely laying thinsulate into the back of the bolster and between the boot side trim and the body panel all the way to the top. Your thoughts?
 
That's precisely what I'm doing next :) I'm applying thinsulate inside the remaining space where it won't compress. Inside the boot trim and the door panels. Reduce reverberation and increase absorption.
 
Great, I'll let YOU experiment then! The site lists 2 thicknesses http://www.carinsulation.co.uk/product/au2020-6_thinsulate_car_insulation_material and http://www.carinsulation.co.uk/product/au3002-2_car_insulation_material Will you be using the thicker stuff? I can't remember whether the backside of the seat side bolsters are hollow, if so I might put the thinsulate in there and also the seat backs in an effort to isolate the boot from the car interior.
 
I will :). I've used the 3002 stuff before on a Yaris to great effect so it will be the thicker stuff. They are sort of hollow with some plastic bracing and protruding arms. But they have enough space for thinsulate.
 
If you haven't already got it, install this https://www.dropbox.com/s/ie5vgl88qq...ip?n=116193361 Go through the steps to download then : Accessories and Equipment, Exterior trim then page 41. This shows rear arch liner removal and on the TSX forum a guy had coated the inside surface of that with Ensolite which is just foam and not absorbent like thick er... thinsulate. He still reported a 20% reduction in noise though. It may be worth installing thick/thinsulate here to stop the noise nearer source.
 
Ah that's where I was going to do the arches from initially, but I thought it would have been too fiddly overall; That's why I took apart the trim.

I've experimented with putting thinsulate around the spare wheel well and finally put the scraps of MLV under my floor mats (which are already heavy rubber) my word its made a huge difference to me! I've ordered some 3.2kg stuff as I can cut it up and fit it nicer than my scraps to hopefully get a better result.

But now I'm stuck as I'm pretty sure I'll be done by then, I have a weird sealing problem to solve where the front windows are leaving a gap between them and the weatherstrip letting more sound than normal in but after that the remaining noise is structural; low frequency rumble which will be an utter pain to try and dial out anyway.

To help you out however I will do a recording of my completed car annotated to the different road surfaces so you can draw up a comparison.
 
Well, I took out one of the rear wheel liners, cleaned it on the inside and stuck the adhesive backed Thinsulate to it. That stuff STICKS. Result is I can now barely hear the noise at town speeds. Much bigger difference than covering the boot arch side liner. Motorways will be the big test, though. I'll report back.
 
Good to hear! I should have said my insulation in the wheel trim is actually thinsulate and mlv. You should be able to spot it in the pictures actually. That could explain the initial differences.

I have just put the 3.2 kg stuff in the front footwells now. And have 1.5m of thinsulate. I might do what you've done and the doors with it.
 
thinboy said:
Motorways will be the big test, though. I'll report back.
Click to expand...
Tried it today - much quieter. With the rest of the thinsulate I have, I think I'll do the plates behind the front wheel liners as per your first guide and then put the rest on the rear inner boot panels near the arches and over the MLV already there.
 
I'm still following this thread with keen interest, though I'm starting to lose track of who did what to where in their cars.

Thinboy, is your post above saying that you've insulated the rear wheel arch liners, so from outside the car? So you didn't have dismantle the entire interior of the car to get a useful noise reduction?
 
I found the biggest reduction in road noise by removing the road wheel and plastic arch liner, cleaning the liner's inner surface and sticking the adhesive backed thinsulate to it. It would also help to put some on the factory sound pad on the boot side of the arch as well, as per post #2.
 
I've ordered some adhesive-backed thinsulate for the rear arches, and some yoga mat for the front. I've got some time off in the next couple of weeks, so I may have a little play wth this. Then a little curse. Then a big curse. Then some bleeding. Then I'll go have a beer.
 
Updated the diagram with all the avenues explored so far;

Yzz2PlS.png


I've done: Lightweight felt, Parcel Shelf, Heavy Floor, Heavy Wheelhouse.

I took a long trip down to East Grinstead at the weekend, and it seems there's still work to do at the front :( the heavy stuff at the front has done a fair bit. But the M40 + M42 are so terrible I might as well have no soundproofing, I might have to apply the heavy stuff higher up in the bulkhead.

I have however solved the splash noise problem on wet roads and will be documenting that soon; A big reduction in water noises when going through puddles as the noise leaks through the door-side weather strip.
 
I added thinsulate to the inner rear arch soundproofing that I'd already done, so that's polyprop liner, thinsulate, steel, Honda soundproofing, MLV/CCF/MLV laminate and thinsulate. Enough? With my leftover thinsulate I'll do the closing panels behind the front wheel liners. I just want to reduce regular dry road noise here - splash noise doesn't bother me - will it have a significant effect?
 
It worked a lot for me because it also meant I had horrible wind noise with the windows fully up, nudging them down would fix it and here's why;

X3dtf4J.jpg


The left diagram shows how the weather strip runs at the top of the door panel, there are two pairs of flanges which you can see contact the window from the door side and the outer panel side. The outside flanges were in full contact but when the window was 100% up the inner flanges would have a tiny gap between them and the window in the "Mine" portion of the diagram. This would leak any noise that got into the door up straight into the cabin; mostly splash noise and wind noise - rough roads would also make it louder as it'd just be channelled up to the glass and bounce around the cabin.

In the picture you can see a yellow strip, this is a 3mm strip of closed cell foam tape used to test if it fixed the problem which it did.

The tape is this; http://www.ebay.co.uk/itm/Black-single-sided-closed-cell-foam-tape-5-metre-coils-x-various-sizes-/221258257686?pt=UK_Crafts_Cardmaking_Scrapbooking_Glue_Tape_EH&var=&hash=item3384051516

12mm x 3mm I believe. I took the door panel off and put it between the two flanges on the interior side so you don't see it, and it's much, much quieter on wet roads especially, with some improvements to rough roads and higher speeds.
 
Luckily, I have absolutely no wind noise or splash noise so this just leaves a low level rumble which I hope thinsulate on the front closing panels behind the arch liner might lessen. I've already got the clips and leftover thinsulate so may as well give it a go. And there IT WILL END!! One musn't become obsessed...
 
Haha, snap - I've made the car fantastic for all my local roads, just there are worse roads out there. Fortunately I will use them maybe twice per year so I'll be calling it a day on mine :) I'm here for advice however and will put some stuff up about soundproofing the doors soon. But I've never seen them as a big source of noise unless your weatherstrip is leaky like it was on mine.
 
On the subject of obsession: I've been trying to work out why your wheel arch thinsulate has worked so well and I think I know why now; The sills will just carry noise along them without any blocking in place; There are foam blocks in the A/B/C pillars that stop the sound travelling up the pillars but not across them, so I'm thinking that the thinsulate is blocking the noise further.

I've been helping a friend with his MK6 golf - very quiet cars but also have minimal soundproofing, except in the wheel arch areas there are big, dense foam blocks in the wings and sills. I might have to do the front arches and try the rears to see if it does anything. Should only take half an hour :)
 
Right. I've done the front arches with some nice bright blue yoga mat, following Gareth's excellent instructions in the first post. Fortunately, I'd ordered some spare clips, because I broke pretty much every one getting them out. The arch liners don't seem to have gone back perfectly flush, so I'm trying a little glue round the edge to see if I can make it tighter. Once that's dry I'll give it a bit of a test drive.

I'll need to order some more clips before I tackle the rear arches. I don't suppose anybody has a diagram of where all the clips are on the rear arches (tourer)? Gareth's original picture for the front was a real help.
 
Can't say I could really tell much difference after the front arch mod, though I have got cloth ears, so I'm not a very good judge. When the clips arrive, I'll move on to the rears.
 
Just a quick update; I've realised that my car should be quieter by design! Turns out I have some lovely tyres on my car;

http://www.uniroyal-tyres.co.uk/generator/www/uk/en/uniroyal/automobile/themes/02_products/01_rain_expert/rainexpert.html

That tread pattern can't be good! Plus both fronts have some noticeable wear along the outside tread blocks, rears look like new. Looks like a rotation + alignment for me to see if it cures whatever remains. Then once they're all worn down some goodyear efficientgrips are in order.
 
coderbyday said:
Then once they're all worn down some goodyear efficientgrips are in order.
Click to expand...
I'd be interested to know how you get on with those - they're on my list for the next set when the current ones have worn out.
 
You must log in or register to reply here.
Top