Low frequency 'boom' in cabin

[Leonblue]

Better suspension and a noticeably heavier tailgate due to the spoiler. Still mine doesn't appear to do it, surely all the car bodies are built to the same tolerances so I wonder if certain tailgates do not correctly conform to the shape of the aperture and are therefore not pressing down equally on all the buffers when shut.

[willkiwi]

@leonblue, i would bet money that is exactly what the problem is.

[ajw1100]

I could read 552 posts or ask a question, guess which I chose

 

Are these problems specific to the hatchback or do they also occur with the estate? The Estate I test drove did not show any signs of pressure booming so I hope my new estate will not Boom Boom either!! (with apologies to Basil Brush)

[Sak]

They appear on both. Estates with power boot are less prone to booming noise.

[Srejber]

They appear on both. Estates with power boot are less prone to booming noise.

Do you think i ged rid of booming with install the power boot? ( if it is possible)

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Edited 2 January, 2015 by Srejber

[Harti]

A quick update on my issue.

 

Since I removed and put back the boot floor to its place more stiff, I can`t really hear the booming anymore. Can be that I am getting used to it after more than a week now, but the first thing I was listening to this morning during my commute to work is this issue and suprisingly I could not really hear it...

[Leonblue]

Wonder if the board  was vibrating over the wheel well and acting like a bass drum? May be worth trying removing the floor completely for those who still have the issue?

[Harti]

Wonder if the board  was vibrating over the wheel well and acting like a bass drum? May be worth trying removing the floor completely for those who still have the issue?

 

Will go home soon on the same road where it was the worse last week and will see!

[Srejber]

A quick update on my issue.

Since I removed and put back the boot floor to its place more stiff, I can`t really hear the booming anymore. Can be that I am getting used to it after more than a week now, but the first thing I was listening to this morning during my commute to work is this issue and suprisingly I could not really hear it...

But It does not explain why the tailgate ajar almost eliminate the issue, maybe another source of noise. To get the boom - painful to ears, it requires some 'membrane' like in the loudspeaker- some sheet of metal which works like a loudspeaker or a piston- something what can compress the cabin air or something what can generate low frequency sound-waves (which are particularly just a pressure fluctuations)

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[GTR27]

Keeping the boot ajar allows pressure to release. Doesn't necessarily mean that the boot is the cause of the sound. Worth investigating the floor at least.

[willkiwi]

The issue has to be the large hatch vibrating like a speaker causing low frequency noise. Its a problem that has happened on other cars. Opening the hatch slightly does not allow pressure to escape rather it prevents the hatch from vibrating. Some hatches have it and some dont probably because the cars that have the boom have a hatch that is not adequately supported on all edges.

Edited 3 January, 2015 by willkiwi

[snala]

As what Will said above. Taking out the boot floor, spare wheel, having rear seats down windows open etc didn't make any difference in mine.

It was definitely the rear hatch causing it, hence why the new buffers made a significant improvement. It's a noisy car anyway, all the MQBs seem to be compared to the mark II but the pressure originated sound is unique compared to the other noises it makes.

Your change in sound Harti could even be your hatch has moved when you opened and closed it to play with the boot floor and now has a better seal this time? If the seals fit properly or stick better they would perform a similar effect to the new sprung buffers in supporting the hatch.

 

What Srejber said about it needing a wide area or membrane to produce low freq sound is spot on, that rear window is huge and the door is super heavy so any chassis movement only needs a few MMs of hatch movement to influence vast amounts of interior air and probably also vibrate whatever is in the way i.e. rear seats, parcel shelf and floor. With the hatch on the half latch, so possibly now only one point of contact only apart from the hinges, it can still be influenced albeit less by the chassis movement, but the air just escapes out the sides and bottom so no resistance and booming.

Edited 3 January, 2015 by snala

[Leonblue]

Although I've not experienced this, I have to concur with the conclusion that the tailgate is the likely cause. On my first car (MK3 Elegance) the side buffers were set at the very top of their travel from new. This car did not show the problem, but there would have been no room for adjustment if it had. I've just checked the new car, the side buffers are at the top too. It appears that those side buffers are wedge shaped and are there to stop side to side movement of the tailgate, another mode that could cause noise and vibration. It may be worth sticking some foam or similar on these side wedges to see if that helps also.

Edited 3 January, 2015 by Leonblue

[ajw1100]

Heard today that my car will be built (Confirmed) week 3 with delivery about weeks 6~7. ANNOYING thing was I was never told the cut off point to change the order :swear: A long email has been sent to the dealer and meeting will follow!!

 

Anyway, I am going to insist that when my car does arrive one of their drivers will drive it on trade plates with me as passenger so I can be sure it does not have any pressure reverberations, dash rattles, suspension squeaks or anything else I don't like. If any do appear they will get them sorted before they take my Avensis in PX!!

[JungleJames]

Heard today that my car will be built (Confirmed) week 3 with delivery about weeks 6~7. ANNOYING thing was I was never told the cut off point to change the order :swear: A long email has been sent to the dealer and meeting will follow!!

 

Anyway, I am going to insist that when my car does arrive one of their drivers will drive it on trade plates with me as passenger so I can be sure it does not have any pressure reverberations, dash rattles, suspension squeaks or anything else I don't like. If any do appear they will get them sorted before they take my Avensis in PX!!

Good luck on that one. When I purchased mine, my dealer seemed put out when I said I wanted to look around the car before paying the money and signing my life away. That was just looking over the car, you are after a lot more.

[Matt Pez]

^^ yep, if you are buying on finance, you have to sign before they register it in your name and if you are paying cash, most dealers usually request the balance to be paid with cleared funds prior to delivery date.

[iDENTITi]

My car still does this. I didn't even try getting this one fixed since last time all I got was "I can't hear it, must be you".

It isn't as bad as the last one, or I'm going deaf.

Worse is the suspension knock crawling over larger speed bumps.

[JungleJames]

^^ yep, if you are buying on finance, you have to sign before they register it in your name and if you are paying cash, most dealers usually request the balance to be paid with cleared funds prior to delivery date.

I paid the last part of my initial payment on the day of delivery, and that's when I signed to start the finance (agreed previously obviously).

But dealer seemed to want to get the money out the way and push me out the door. Seemed a bit surprised when I said I wanted to make sure the car was OK before signing anything and accepting the car.

[willkiwi]

My wagon has rear suspension knock. Most noticeable over small bumps at slow speeds. Its the biggest annoyance for me. Ive been told by the dealer that the wagon has an issue which causes a knock so will see if the noise is gone when the fix is done. IMHO my mark 3 vrs has worse suspension noise than my mark 2 vrs

Edited 3 January, 2015 by willkiwi

[ajw1100]

Well, I got an email from dealer boss with copy to group boss to arrange a meeting re my 'dissatisfaction' with level of service to date. I have seen unregistered (No plate) cars driving around only on trade plates so assume this is possible, nothing to lose anyway!

[ajw1100]

Ohps, quote missing in above post.

 

Good luck on that one. When I purchased mine, my dealer seemed put out when I said I wanted to look around the car before paying the money and signing my life away. That was just looking over the car, you are after a lot more.

Well, I got an email from dealer boss with copy to group boss to arrange a meeting re my 'dissatisfaction' with level of service to date. I have seen unregistered (No plate) cars driving around only on trade plates so assume this is possible, nothing to lose anyway!

[JungleJames]

Ohps, quote missing in above post.

 

Well, I got an email from dealer boss with copy to group boss to arrange a meeting re my 'dissatisfaction' with level of service to date. I have seen unregistered (No plate) cars driving around only on trade plates so assume this is possible, nothing to lose anyway!

Good luck. Hope you get somewhere.

[DougL]

^^ yep, if you are buying on finance, you have to sign before they register it in your name and if you are paying cash, most dealers usually request the balance to be paid with cleared funds prior to delivery date.

 

If you're paying cash then use a debit card. It's instant. My dealer told me to go out and look at the car before I paid for it. I came back in noting a couple of things which were sorted out instantly... paid and drove off.

[ajw1100]

^^ yep, if you are buying on finance, you have to sign before they register it in your name and if you are paying cash, most dealers usually request the balance to be paid with cleared funds prior to delivery date.

 

Its on 0%, I just want to ensure that we will not have this problem, my wife suffers from tinnitus so its important we check first, hopefully this problem will not occur with the new car and we can drive away happy.....

[Srejber]

As what Will said above. Taking out the boot floor, spare wheel, having rear seats down windows open etc didn't make any difference in mine.

It was definitely the rear hatch causing it, hence why the new buffers made a significant improvement. It's a noisy car anyway, all the MQBs seem to be compared to the mark II but the pressure originated sound is unique compared to the other noises it makes.

Your change in sound Harti could even be your hatch has moved when you opened and closed it to play with the boot floor and now has a better seal this time? If the seals fit properly or stick better they would perform a similar effect to the new sprung buffers in supporting the hatch.

What Srejber said about it needing a wide area or membrane to produce low freq sound is spot on, that rear window is huge and the door is super heavy so any chassis movement only needs a few MMs of hatch movement to influence vast amounts of interior air and probably also vibrate whatever is in the way i.e. rear seats, parcel shelf and floor. With the hatch on the half latch, so possibly now only one point of contact only apart from the hinges, it can still be influenced albeit less by the chassis movement, but the air just escapes out the sides and bottom so no resistance and booming.

One detail: my tailgate (estate) is quite stiff closed I tried to push them on left and right side down even with severe power but it seems to be rock solid. i realised that those rubber buffers are placed lower- closer to the bottom than on other MQB cars - Leon and Golf have the buffers a bit higher (closer to hinges) but Octavia Combi has its buffers integrated to rear light assembly- closer to latch - maybe too at the bottom. anyway, it is hard to imagine it moves even one millimeter in vertical direction in my case.

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Edited 4 January, 2015 by Srejber