Low frequency 'boom' in cabin

[PetrolDave]

9 minutes ago, cr_2dman said:

 

i have the booming issue on my skoda octavia facelift mk3 , 1.5 tsi. It irritates me. My wife doesn't hear it (or doesn't care)

I've even driven the exact same car in a test center, it also had the boom.

 

I spent several years working on a system that electronically cancelled boom caused by 4 cylinder engines - at first it was really surprising how many people just don't hear the boom, but it seems that some people just aren't sensitive to those type of low frequency sounds.

[TonisT]

The biggest help in my case was to block the sound movement on the roof edge channel with Loctite automotive foam. There are small holes on the roof where roof beam connects to B pillar. Unfortunately the car is built so that the roof edge beam coming from A pillar is hollow and directs all the sound you try to  suppress directly without obstruction to the B pillar and straight to your ear. I had done full sound deadening to the car (interior out, floor and roof etc) and it still hurt my hears. When I blocked the sound movement from the A pillar to the B pillar and to my ears I got the relief that I was looking for for so long. I would still like to lessen the front tire noise on extremely rough surface but other than that I'm happy enough not to try anything else.

I put some foam on top of the  B pillar holes, to the bottom of B pillar and to the bottom of A pillar

 

Hint what to try was in superb forum.

[Thomas_Denmark]

On 28/08/2020 at 08:37, TonisT said:

The biggest help in my case was to block the sound movement on the roof edge channel with Loctite automotive foam. There are small holes on the roof where roof beam connects to B pillar. Unfortunately the car is built so that the roof edge beam coming from A pillar is hollow and directs all the sound you try to  suppress directly without obstruction to the B pillar and straight to your ear. I had done full sound deadening to the car (interior out, floor and roof etc) and it still hurt my hears. When I blocked the sound movement from the A pillar to the B pillar and to my ears I got the relief that I was looking for for so long. I would still like to lessen the front tire noise on extremely rough surface but other than that I'm happy enough not to try anything else.

I put some foam on top of the  B pillar holes, to the bottom of B pillar and to the bottom of A pillar

 

Hint what to try was in superb forum.

 

Hi TonisT

 

I have done the same work to my Octavia as you regarding sound deadening, and the result was still not as good as I wanted. Did you by any chance take some photos of the work you did with the foam? This sounds very interesting in my ears if this could solve the problem.

[TonisT]

No, I did not take any pictures.

[Michaeldavis39]

Toni's, I am trying to understand the roof foam filling you did on your car as I would like to do the same, I don't know what a and b pillar are as I'm not in the motor industry so that's my first question, secondly did you have to remove any panels from the interior to squirt this foam inside or did you squirt from outside on the roof through the holes you found I'm guessing under the roof trim??

 

Thanks in advance

 

Michael

[TonisT]

https://static.ed.edmunds-media.com/unversioned/img/glossary/pillars.jpg

 

I used special automotive foam - Loctite TEROSON PU 9500 FOAM

I removed inside panels from  A and B pillars and squirted some foam inside through the holes there. So from inside. There are no holes in outside.

Places where I squirted were on top and on bottom of B pillar (There are 2 square holes on top and through those. Aiming the nozzle to the front from the forward hole and to the back from the rear hole). However you need to be careful because foam will expand and  some will come out of those holes. Side airbag goes right next to those holes so you need to cover the airbag and clean the area carefully afterwards. A pillar has a small opening low close to dashboard. I put some foam through that hole also. Afterwards cleaned and re-mounted everything. 

I believe that the 2 square holes are the main place that will direct sound right to your ears. I'm still considering doing the same to the C and D pillars (I have an estate) but to be honest it is now so quiet that I will probably not bother. Since now I have full sound deadening plus interrupted sound channel on the roof edge, I have to say that the car is now nice place to be in.

Oh, Just in case some one is interested, at least in my car the rear door made pretty nice vibrating sound- It has 2 hinges on top, one lock on the bottom  and 2 bumpers on the side. I did put some rubber pieces on the 2 bottom corners on the same line as the lock is. It removed some annoying vibrations pretty well.

[Michaeldavis39]

Great I was so looking forward to doing this until I found that Teroson 9500 isn't available in UK. Oh well

[ima]

Lots of UK alternatives. Google is your friend on this.

[Michaeldavis39]

I can find lots of expanding foam but non specific for use in cars ima- it would be helpful if you gave a name of a product thanks.

 

Michael

[Thomas_Denmark]

12 hours ago, TonisT said:

https://static.ed.edmunds-media.com/unversioned/img/glossary/pillars.jpg

 

I used special automotive foam - Loctite TEROSON PU 9500 FOAM

I removed inside panels from  A and B pillars and squirted some foam inside through the holes there. So from inside. There are no holes in outside.

Places where I squirted were on top and on bottom of B pillar (There are 2 square holes on top and through those. Aiming the nozzle to the front from the forward hole and to the back from the rear hole). However you need to be careful because foam will expand and  some will come out of those holes. Side airbag goes right next to those holes so you need to cover the airbag and clean the area carefully afterwards. A pillar has a small opening low close to dashboard. I put some foam through that hole also. Afterwards cleaned and re-mounted everything. 

I believe that the 2 square holes are the main place that will direct sound right to your ears. I'm still considering doing the same to the C and D pillars (I have an estate) but to be honest it is now so quiet that I will probably not bother. Since now I have full sound deadening plus interrupted sound channel on the roof edge, I have to say that the car is now nice place to be in.

Oh, Just in case some one is interested, at least in my car the rear door made pretty nice vibrating sound- It has 2 hinges on top, one lock on the bottom  and 2 bumpers on the side. I did put some rubber pieces on the 2 bottom corners on the same line as the lock is. It removed some annoying vibrations pretty well.

 

Thank you for your very detailed post. At first I was a little skeptical about the foam, but I can see from the explanation on the Loctite website thats it's actually made for that purpose.

[Michaeldavis39]

Anyone know the name of a suitable foam that's sold in UK? Or is anyone willing to send me a can of the Teroson over if I send the money please??

 

Michael

[ima]

Hi Michael

 

This one has significant sound deadening properties and is fire retardant.

 

Soudal Fire & Acoustic Expanding Foam 600ml B2

As an alternative this may achieve similar properties

 

DEI Boom Mat Spray On Foam Sound Deadening / Noise Reducer - 18oz Aerosol

 

The alternative is to use closed cell sound deadening foam sheets that you cut into strips and likely to be just as effective and less messy. Worth discussing with car sound proofing companies such as the sound deadening shop etc.  
 

Henkel Uk distribute the Terason

 

 www.carrepairsolutions.co.uk/en/products/body-protection/acoustic/teroson-pu-9500-foam.html

 

 

 

Edited 31 August, 2020 by ima

[Michaeldavis39]

I think you need to be in the trade for Henkel as there's no stores mentioned on their website. I agree the deadening sheets would be less messy

[ima]

The DEI Boom Mat Spray On Foam Sound Deadening / Noise Reducer  likely achieve the same. The trick is changing the resonance frequency with sound dampening/sound absorption which won’t really on the messy foam application. I certainly wouldn’t feel confident with foam as a DIY job but happily apply the alternatives in the places Tonis T describes. 

[TonisT]

I did not find Teroson anywhere in here, Estonia, either. However I just wrote company that sells and imports Loctite stuff and asked for quotation. Not listed on their site but they did order it for me.

 

I believe that problem is that on the edge of the roof there is a hollow section from front to back. You can sound deaden all you want but through this hollow section sound will travel unobstructed and there are basically openings next to you ear on top of the B pillar. Main thing that foam does in this case is just fill the void so that sound could not travel through it.

 

You can take a tube and sound deaden the hell out of it's walls but if you put one end to your ear and some one screams through the tube on other end, the deadening will do nothing. I just plugged the tube with foam so to speak.

At least this is my understanding.

 

You could try vibration deadening mat over the holes. Maybe it will also work however when I did sound deadening mats and other stuff I did not cover the holes on top of B pillar with the mat so I have no idea how well it would work. As I did put some foam on the bottom of A pillar I believe (at least I want it to be true  ) that I obstructed straight path from engine bay to the hollow section bit better. There are many holes in this section for trim clips etc but I think now the engine compartment noise is bit better obstructed than it would be with just plugging the holes on top of the B pillar.

 

Unfortunately My ears are pretty bad when it comes to noise tolerating. I guess I have destroyed my hearing motorcycle riding without earplugs and lumber works without earplugs. So my ears will probably start hurting bit earlier and on lower noise levels than for some people. I have sound deadened last couple cars I have owned and usually stop when I find it tolerable because I'm lazy  . Octavia is the first car that i have ever have to do full deadening and I mean everything. However, it was still uncomfortable for me. Dealing with this hollow section have improved things enough that I think that I will leave it as is and call it good enough.

 

Disclaimer: This worked for me. Every person perceives sound and noise differently and this might not be the wonder medicine that you have been hoping for. However for me it lowered the irritating noise that gave me headache enough that I feel much more comfortable in the car.

Edited 31 August, 2020 by TonisT

[Michaeldavis39]

Toni's did you also fit the rear tailgate redesign fittings? The new ones are spring loaded. I too find my hearing badly affected by this car, fine on smooth roads but not on any other. My previous car was a Citroen C5 2007 model and was far superior in terms of noise dampening- I remember the boot area had deadening pads from factory and the boot carpet had thick jute attached to it- the jute on Octavia is half the thickness and no deadening pads except a tiny piece in the spare wheel well area, the Citroen also had thick jute under the entire carpet area and an extra thick rubber and jute combo on the bulkhead - I really miss that car at the moment especially the comfort- even getting in and out if the car was easier! So much for progress I'm now having to soundoroof a 2015 car which is something I haven't had to do since I had a Ford Focus MK1 in 2000!

 

Michael

[TonisT]

No, I did not fit them. I understood they were for hatch only and would not fit the estate. Was I wrong?

[Michaeldavis39]

I don't know Toni's. I ordered some from Canada and they have now refunded them because Hyundai have none in stick anywhere around the world so looks like I won't be fitting them either. I'm not having much luck at sorting this noise problem so far it's becoming very frustrating.

Micgael

[Michaeldavis39]

My wife suggested earplugs- think Skoda could have supplied them as standard- not so simply clever. I don't think I will get another Skoda after this experience it has really put me off.

 

Michael

[fabdavrav]

Rear subframe harmonic damper??..only for the 2wd multilink rear suspension though.....I did a how to guide over on the MK7 forum..

 

https://www.golfmk7.com/forums/index.php?threads/how-to-retro-fit-the-rear-subframe-harmonic-damper-from-the-audi-a3-saloon-2013.369369/

 

[Michaeldavis39]

Unfortunately my car is the solid rear beam axle - unless anyone knows whether the golf dampers can fit a solid axle?

 

Michael

[Michaeldavis39]

Toni's how do you remove the B pillar trim?? I can see explanations on how to remove A pillar but not the B.

 

Thank you

Michael

[Michaeldavis39]

Well after fitting a Volvo harmonic damper to my axle beam, fitting silent sound deadening pads to the spare  wheel well and under the back seat, squirting some foam into the front drivers side A pillar( too cold now in UK to go further with this) also replacing the tailgate stops for the new heavily sprung stops, putting some sound proofing felt under back seat and in the foot well, fitting a spare wheel and tool kit plus a full set of the rubber Skoda mats interior and boot area, fitting the full size engine tray and the middle large undershield I can say that my car is much better than it was when I first got it a month ago. I haven't finished with these modifications as I need to change front tyres for Goodyear all season ones, order more dampers, squirt more foam next year in warm weather and add more sound insulation under the front carpets, fitting sound deadening pads to the rear wheel arches after taking out the carpet - then I will have done as much as is possible to make the car more pleasant to be in when driving- it's a lot of work but I've seen be benefits on every single upgrade - the best two so far were the foam and the Volvo damper.

 

Michael

Edited 29 September, 2020 by Michaeldavis39

[Thomas_Denmark]

7 minutes ago, Michaeldavis39 said:

Well after fitting a Volvo harmonic damper to my axle beam, fitting silent sound deadening pads to the spare  wheel well and under the back seat, squirting some foam into the front drivers side A pillar( too cold now in UK to go further with this) also replacing the tailgate stops for the new heavily sprung stops, putting some sound proofing felt under back seat and in the foot well, fitting a spare wheel and tool kit plus a full set of the rubber Skoda mats interior and boot area, fitting the full size engine tray and the middle large undershield I can say that my car is much better than it was when I first got it a month ago. I haven't finished with these modifications as I need to change front tyres for Goodyear all season ones, order more dampers, squirt more foam next year in warm weather and add more sound insulation under the front carpets, fitting sound deadening pads to the rear wheel arches after taking out the carpet - then I will have done as much as is possible to make the car more pleasant to be in when driving- it's a lot of work but I've seen be benefits on every single upgrade - the best two so far were the foam and the Volvo damper.

 

Michael

Hi Michael

 

I have done most of the work you have done, and it's also getting better. Could you post a picture of the Volvo dampers in situ and also the tailgate stops?

 

Best Regards Thomas

[Michaeldavis39]