Low frequency 'boom' in cabin

[PetrolDave]

'11 & '12 plates would have been an Octavia 2 which was a completely different design to a '14 plate Octavia 3.

 

Owners who have switched from Octavia 2 to Octavia 3 have also commented that the road noise ('boom') is much worse on the Octavia 3, seems this is one consequence of the new lighter design.

[VRSJEFF]

Hi all, I'm new to the group having recently bought a 2015 VRS wagon/estate.

 

I was loving the car for the first half tank of fuel but then began to notice my ear drums pumping/hurting as the car drove over road corrugations around town. I did some googling, then before I knew it, found myself reading this very interesting thread on Briskoda!

 

I am yet to check tailgate fitment, catch and stopper settings, but will try and see how it goes.

 

In the meantime, I also found this frighteningly similar and lengthy thread over in Tesla Model Y land... enjoy!

https://teslamotorsclub.com/tmc/threads/ear-pain-pressure-help.205783/

[mjfend26]

Has anyone ever fixed this? 

[Michaeldavis39]

I have reduced the noise but not completely eliminated it. I have posted some time ago regarding what I have done which you will find if you do a search. My next improvement will be replacing the original Sachs oil filled shock absorbers front and rear for Bilstein gas shocks next spring- current front ones have slight weap which was advisory on mot just recently so need replacing.

[Michaeldavis39]

I am currently testing a new solution to the noise produced by these cars- see photo attached

[mjfend26]

32 minutes ago, Michaeldavis39 said:

I am currently testing a new solution to the noise produced by these cars- see photo attached

What's the plan lol?

[Michaeldavis39]

I was going to throw these rolls of jute in the tip but thought I would see if I could have a quiet drive this winter instead by leaving them in the boot lol

[mjfend26]

14 minutes ago, Michaeldavis39 said:

I was going to throw these rolls of jute in the tip but thought I would see if I could have a quiet drive this winter instead by leaving them in the boot lol

Did it work lol?

[Michaeldavis39]

Nope 😂

But you cant say I didnt try!

[PetrolDave]

Work done over 30 years ago at Lotus found that the boom was caused by tiny vibration inputs exciting cabin resonances. These inputs can come from engine imbalances (especially with an inline 4 cylinder engine which has out-of-balance forces at twice engine rpm) and road vibrations fed through the suspension. These are both low frequencies which need lots of heavy sound deadening to prevent the cabin resonances being excited, hence why the boom is worse on non-premium brands and is becoming worse with the emphasis on light weight (thinner panels will have stronger resonances).

 

So the first question to ask is whether the frequency (tone) of the boom is related to engine speed or road speed. Then you know whether to try and reduce engine vibration inputs or road vibration inputs.

[langers2k]

There is a TPI regarding this issue as mentioned in this thread: https://www.briskoda.net/forums/topic/446755-new-rear-shock-absorbers-on-warranty

 

 

[Michaeldavis39]

Fairly sure its coming from suspension as the noise becomes excessive when I drive over a specific part of road slowly which has lots of small undulations in it- if I drive over the same part of the road at higher speed the noise lessens considerably. I have new Bilstein shocks to fit next spring - I believe Sachs shocks are oil filled and Bilstein are gas filled - correct me if I am wrong? Maybe these new shocks will make some difference. Joking apart but the design of these cars and the reduction in sound deadening, light panels etc is the problem which wont ultimately go away even with copious amounts of sound deadening hence the mk4 which is a new platform with lots of modifications to improve noises and it is a much better car in this respect. 

[KenONeill]

1 hour ago, Michaeldavis39 said:

I believe Sachs shocks are oil filled and Bilstein are gas filled - correct me if I am wrong?

OK. There is no such thing as a "gas filled damper" in terms of working fluid. What there actually are are "gas pressurised dampers" where you get a sealed volume of pressurised gas above the damper oil that is the working fluid. This design gives increased resistance to aeration of the oil working fluid, and hence to damper fade.

[Michaeldavis39]

Thank you Ken for clearly explaining the composition of dampers.

[Di_Greenio]

Came across this thread by chance and so glad I did! I have had my 64 plate TDI VRS hatch for just over 2 years and the boom was so bad especially at lower speeds round town that my youngest even mentioned it to me.  I had fitted the harmonic damper as previously mentioned here obviously to not much avail and had just learned to put up with the noise. So when I saw this thread I became interested in it again.  I happened to jump back to page 50 and saw the comments on the boot stoppers and possibly adjusting them so thought I would give it a try.  They were sitting sort of half way so I adjusted them last night to as high as they would go. Unbelievably it seems to have worked for me, the booming has all but stopped, one of the lucky ones. The only thing now is it makes the clanking noise coming from the rear suspension a bit more noticeable. 🙈 That's next on the fix list!

[Michaeldavis39]

Di Greenio thats great news. I replaced my boot stoppers with the modified Skoda replacement ones which made a difference to the sound of the boot closing- sounded much more solid but I didnt notice any other difference. Im looking forward to having the Bilstein shocks fitted front and back next spring which from what I have read will make a big difference- fingers crossed lol.

[Di_Greenio]

@Michaeldavis39 I couldn't believe it but now I might regret not buying B4's over the last weekend.  Which ones did you opt for?

[Michaeldavis39]

B4

 

Edited 29 November, 2022 by Michaeldavis39

[Gayrisafi]

@Michaeldavis39So, did the new shocks make a difference?

 

Also, is anyone experiencing the same issue in Karoq?

[Snoopyy]

I bought 1.6 petrol (of december 2019 with 58k km) a month ago an this sound is driving me crazy... 61 pages and no effective solution.

I didn't notice this problem at the moment of the test drive, that time there were backseats that were making a strange noise but the dealer fixed it.

I have the station wagon version, i tried to pull out the weel from its well but nothing changes, also lowered tires pressure, it helped a bit but when concrete is not good it's a pain to be inside the car.

[WodaCodaSkoda]

I've spent the last few months adding some sound deadening to my Mk3. I'll share what I've found in the hope that it's useful...

My conclusion is that while the engine is almost silent on mine, sadly the chassis and lack of sound treatment makes the Octavia a noisy car on the motorway, on anything but the smoothest of surfaces. However, it is possible to reduce the booming so that it is below the pain threshold(!)

 

Main thing I did was buy a 3.4 sq m pack of Noico 2mm butyl mat (black). It cost about £50.

I did this work in Nov-Dec in Scotland. I used a heat gun (hairdryer would do) to heat the metal to 30-40 degrees for good adhesion.

 

First I stuck it all around the spare wheel well. - This made the rear sound a bit more 'solid' when driving over bumps. 

Then I lifted the rear seats and added noico to the bare metal under the rear seat. - Maybe added a tiny bit more "solidity". Car was still quite noisy.

 

I then treated myself to 4 new tyres, and got the front wheels aligned (tip - if you are non-VRS model and have standard suspension, you only need front alignment - cost about £60). The wheel alignment was quite a bit out, this reduced the roar from the front, but there was still a lot of road noise.
I can't say I've noticed a huge difference from the new tyres. They are Goodyear EfficientGrip Performance 2. They are fine but I don't think the bulk of the noise was from the tyres.

 

Now the main noise was a painful low frequency 'pressure', especially on bad motorway surfaces. 

 

Next I treated the B-Pillars (as in this post). I ordered some small pieces of acoustic foam to stuff into the bottom sill, and inside the B-pillar itself, taking care not to interfere with airbags and seatbelts.

I covered the large 'hole' in the b-pillar metal with Noico, and covered the rear of the bottom plastic trim with Noico. - This helped reduce the 'pressure' feeling in my inner ears.

 

Lastly, and perhaps most importantly, it was now obvious that there was a lot of noise coming from the front footwells. I lifted the easily accessible parts of the carpet in the front footwells and added Noico under there. What is under there is basically very thin, very resonant bare metal. This is where Skoda have added their biggest pieces of ineffective sound deadening mats, which shows they realise this is a noisy area. 

 

I added a layer of Noico to the footwells. This helped to the same extent as lining the spare wheel well did. Now when I go over a bump, the front sounds more solid.

However it is still noisier than in a lot of cars. 

I might still add a second layer of Noico, and maybe some MLV (Mass Loaded Vinyl) over this to further absorb the noise in the footwells. As I was in a rush, I found some 1cm thick rubber mats in Screwfix (designed to go under a washing machine). I put 2 layers of this under the carpet in the front, which helped a fair bit.

 

 

I'll happily go into more detail if anyone has questions (If there's interest I could even make a project thread with photos?). Oh, I also adjusted the rubber 'spring' type stoppers on the bottom of the boot lid (there was a gap of about 5mm, I unscrewed them so that they just grip a piece of paper when boot is closed (there's a video somewhere in this thread).

And I also bought a Z-shaped rubber seal strip for £5 on ebay and attached it to the front edge of front doors - this helped reduce wind noise.

 

PS if it's any small consolation, while the mk3 does seem to be particularly bad for noise, check out the Range Rover and Lexus forums  haha they have the same issues - it's maybe all relative...

 

 

 

[Mastercard]

Hi, 

i have a Octavia 1.5TSI facelift (MY 2020). I probably have the trunk ajusters that the people are talking about in this forum. But Im pretty sure I hear a droning sound in lower speeds. 

One thing I have noticed, when driving and turning my head 90 degrees to the side (one ear aimed towards the trunk compartment) I hear like the trunk is open. You know the feeling lite a window is slightly open. 

Maybe I need to adjust my trunk??

 

I have owned the car for 2 weeks, when I test drove it, I could not hear the sound (it was raining that day). Sometimes I just want to burn the car to the ground when I hear road noise, droning etc. Feels like the sealings are not door sealing enough as well. 

[HeavyMetalRich]

Just to give @fabdavrav some feedback on his experiment, I fitted the harmonic damper to the rear subframe of my Octavia and instantly noticed a quieter vehicle on my usual commute. It certainly reduces rattling from the rear suspension and reduces other noise transmitted through that into the cabin. A definite improvement IMO.

 

I can't say that I've noticed the drumming/logs tumbling sound that others have heard but that might be drowned out in my car by the sawblade worn tyres causing a worn wheel bearing type drone in mine?? Next for me will be wheel alignment and some new tyres when they wear out.

 

[Mastercard]

6 hours ago, HeavyMetalRich said:

Just to give @fabdavrav some feedback on his experiment, I fitted the harmonic damper to the rear subframe of my Octavia and instantly noticed a quieter vehicle on my usual commute. It certainly reduces rattling from the rear suspension and reduces other noise transmitted through that into the cabin. A definite improvement IMO.

 

I can't say that I've noticed the drumming/logs tumbling sound that others have heard but that might be drowned out in my car by the sawblade worn tyres causing a worn wheel bearing type drone in mine?? Next for me will be wheel alignment and some new tyres when they wear out.

 

Could you send me the link for these dampers?

[fabdavrav]

13 hours ago, Mastercard said:

Could you send me the link for these dampers?

 

The detailed thread on the item that I wrote a few years back..

 

How to retro-fit the rear subframe harmonic damper from the Audi A3 Saloon (2013->) | GOLFMK7 - VW GTI MKVII Forum / VW Golf R Forum / VW Golf MKVII Forum

 

Its just one item & two nuts, only for the cars with the multi-link rear suspension