[Oksana]

Originally Posted by Aladinnu

The main reason i did the insulation was the engine noise, but the road noise is a lot lower now. If i put it in N at 60mph it feels like floating.... no noise.
And yes the you need to remove the belt cover pillar, the one on top and the one and bottom to. You will notice big hole down that goes straight in to the floor. You will also find a piece of foam insulation but it really doesn t do the job.

Ok great thank you!

[PChem]

A slightly bent wheel rim can create low frequency noise. Does the droning noise change frequency with speed?

Here is a noise thread and post #961 talks about a gap issue. https://f30.bimmerpost.com/forums/sh...781339&page=44

[PChem]

Around post #36 of the above thread link there is a fix relating to the sunroof. The entire thread is likely worth reading.

[Oksana]

Originally Posted by PChem

A slightly bent wheel rim can create low frequency noise. Does the droning noise change frequency with speed?

Here is a noise thread and post #961 talks about a gap issue. https://f30.bimmerpost.com/forums/sh...781339&page=44

Thank for the info!
No the frequency stays more or less the same, just gets louder as the speed increases. How would I check if my rims are bent?

I dont have the foam in my door seals as shown in that thread which is interesting. I’m going to investigate the gap issue tomorrow.

Thanks again!

[HighlandPete]

Originally Posted by Oksana

I dont have the foam in my door seals as shown in that thread which is interesting. I’m going to investigate the gap issue tomorrow.

Personally I believe the F3x models of the 3-series was not intended to be as quiet as some were/are wanting. The sound insulation infill illustrates the point. It is fitted to some models like the diesels, to help reduce engine noise.

I recall when the F30 was first criticised, by some, for the noise levels. I looked at a few examples, and it seemed the petrol engine models at the time, (at least in the UK), never had the wing panel fitted with the insulation.

Stepping back, the 3-series is supposed to be more sporty, not as insulated from the road as say a 5-series, which has the insulation across the range.

[328iX]

Originally Posted by Oksana

Thank for the info!
No the frequency stays more or less the same, just gets louder as the speed increases. How would I check if my rims are bent?

I dont have the foam in my door seals as shown in that thread which is interesting. I’m going to investigate the gap issue tomorrow.

Thanks again!

Diesel only

[Billfitz]

Originally Posted by HighlandPete

the 3-series is supposed to be more sporty, not as insulated from the road as say a 5-series, which has the insulation across the range.

My F34 is as quiet, or better, than any other car I've owned, perhaps because it was originally designed for the Chinese market as a relatively inexpensive limo. It's only 5 inches longer than the F30 but weighs 300 pounds more, and having lifted the carpets I know the insulation padding beneath is unusually thick. If I had noise problems the first thing I'd do is to pull the carpets and liners and add 80 mil vinyl mastic everywhere I could., like this: https://www.amazon.com/dp/B07ZKLKHN5...NsaWNrPXRydWU=

[J555]

Strange, as I do consider F31 to be a surprisingly well-isolated wagon.

When I bought mine, it had the 225/255 19" Bridgestone S001 run-flats and they were noisy. Changed them to Eagle F1 A5 (possibly the most silent UHP tires) and I can barely hear them, albeit I went up with size to 245/275. While not silent tires, the PSS should not be as noisy as run-flats.

I did a three-layer sound deadening of all doors and it really transformed the car. Much better sound isolation from outside (while keeping the engine noise), with the feel of a 5-series. You can do sound deadening of anything, including floor, wheel wells, firewall,... However, it can be expensive and adds weight. Sound-isolating window foil is another option, but I really don't think it is needed.

Considering that you are fine with the other cars on run-flats, I would suggest to wait few hundred miles more and then have a closer look at the tires...

[SteveInfante]

Is the pano roof cover open? I keep mine closed because there's a significant difference in noise.

[Billfitz]

Mastic on the outer door panel is good. There's no need to replace the original foam liner on the doors if you cover the door liners. Foam does next to nothing, so cover the door liner with mastic as well.

[J555]

Originally Posted by Billfitz

Mastic on the outer door panel is good. There's no need to replace the original foam liner on the doors if you cover the door liners. Foam does next to nothing, so cover the door liner with mastic as well.

Each layer has its specific purpose and the combination is required to address all the areas properly (as sound insulation, vibrations, anti-squeak, water resistance, audio quality, heat insulation, etc.). For noise absorption, such one inch thick insulation foam (with vibration-damping coating underneath) does a lot.

[Billfitz]

There's no need to explain what these layers do, I make my living as an acoustical engineer. Foam insulation up to two inches thick is only effective in damping high frequencies. High frequency damping between the door panels doesn't do anything, because there are no high frequencies there to damp. Foam is effective when it covers reflective surfaces within the listening space, reducing high frequency early reflections.

[Aladinnu]

Originally Posted by Billfitz

There's no need to explain what these layers do, I make my living as an acoustical engineer. Foam insulation up to two inches thick is only effective in damping high frequencies. High frequency damping between the door panels doesn't do anything, because there are no high frequencies there to damp. Foam is effective when it covers reflective surfaces within the listening space, reducing high frequency early reflections.

Well said. I had a vw that i used paint insulation on all interior that turned in to a gummy rubber , result was above expectations. I had subwoofer+amp and before that i could hear the bass outside the car very loud, after the insulation was verry quiet. I don t recommend using only foam layers. My advice is first apply a layer of paint insulation and after stick the foam.

[rak299]

My 340ix got quieter when I replaced the original fun-flats by go-flats

[Billfitz]

Originally Posted by Aladinnu

I don t recommend using only foam layers. My advice is first apply a layer of paint insulation and after stick the foam.

Unless it's in place where sound can bounce from one point to another foam isn't what you want to use. The space between the door liner and the door doesn't allow for sound wave development, so there are no sound wave reflections to damp. What you do want is to add mass to the liner, to reduce its ability to vibrate, and in so doing transmit sound into the car interior. The greater the mass the more effective it is, so that's best accomplished with vinyl mastic. The same applies to all of the sheet metal in the car. Whenever I've done mods that required pulling trim I'd add mastic to the sheet metal underneath it and/or to the inside of the trim. It's not because I felt the need for it, but as long as the trim was off anyway it couldn't hurt to do it. The one area where foam could be beneficial is on the floor, but that's already well damped against high frequency reflections by the carpet and the liner below it. But those have minimal effect on low frequencies, so putting mastic on the sheet metal underneath the liner would address that.

[Aladinnu]

I had some time to work again on my f30, i did both front wheel weels and rear left. Now when i took it for a drive i had the feeling that my rear right window is not fully closed because of the noise coming from the back. Really great improvement!!!

[Billfitz]

If you want to add sound damping to the wheel liners it's best to remove them and put it on the inside, either on the liners or on the sheet metal underneath them.

[Oksana]

Originally Posted by Aladinnu

I had some time to work again on my f30, i did both front wheel weels and rear left. Now when i took it for a drive i had the feeling that my rear right window is not fully closed because of the noise coming from the back. Really great improvement!!!

Thanks for the reply, really encouraging to hear it made a difference for you. Can I ask:
- which materials did you use?
- how much of the arch did you cover? The picture you posted shows patchy cover over the visible part of the wheel arch. Was that the finished product or did you go on to cover more of the arch that can’t be seen in that picture?

Thanks again:-)

[Aladinnu]

Originally Posted by Oksana

Thanks for the reply, really encouraging to hear it made a difference for you. Can I ask:
- which materials did you use?
- how much of the arch did you cover? The picture you posted shows patchy cover over the visible part of the wheel arch. Was that the finished product or did you go on to cover more of the arch that can’t be seen in that picture?

Thanks again:-)

The picture is from front left wheel, i did as much i could and specially the upper area , you can easy find the area where u need to insist by simply knocking the pannel with empty hand. The rear wheels are really the big noise reason, big area with no sound deadening. I used 5mm sound deadening with aluminium and special foam that sticks. Really good stuff and not expensive.

[blau3er]

Interesting thread - and sorry to re-open it, but it beats starting a new one!

I am about to tackle some sound insulation of the 4 doors in my F31 (following a Bang & Olufsen audio retrofit). It sounds amazing, but it would be great to elevate it further with some insulation.

What is the best approach? I know the vapour barrier will have to be removed to allow access to the door cavity.

Am I correct understand that a layer of butyl based insulation matting should be applied to the back of the outer door skin - then replace the vapour barrier and cover it with another layer of butyl based matting?

What is the best option for the reverse of the door card - further butyl based matt - or foam as pictured here in the thread?

Finally - what can be done around the sub enclosures - is there any room to allow a layer of butyl matt either inside the plastic sub enclosure itself - or on the bare metal floor pan underneath where the sub enclosure sits?

I am intrigued to see that some deadening in the B pillar might also lend itself to helping the sound of the under-seat woofers too.

[Billfitz]

Add vinyl mastic of the type I already linked. I wouldn't put it on the door sheet metal, as the adhesive probably wouldn't hold when the sheet metal gets hot, allowing it to fall off. I put it over the original vapor barrier. Adding some to the woofer enclosures wouldn't hurt, but most of what the woofers cause to vibrate is buried under the floor in the resonant chambers where you can't get at it.

[Samir72]

Originally Posted by blau3er

Interesting thread - and sorry to re-open it, but it beats starting a new one!

I am about to tackle some sound insulation of the 4 doors in my F31 (following a Bang & Olufsen audio retrofit). It sounds amazing, but it would be great to elevate it further with some insulation.

What is the best approach? I know the vapour barrier will have to be removed to allow access to the door cavity.

Am I correct understand that a layer of butyl based insulation matting should be applied to the back of the outer door skin - then replace the vapour barrier and cover it with another layer of butyl based matting?

What is the best option for the reverse of the door card - further butyl based matt - or foam as pictured here in the thread?

Finally - what can be done around the sub enclosures - is there any room to allow a layer of butyl matt either inside the plastic sub enclosure itself - or on the bare metal floor pan underneath where the sub enclosure sits?

I am intrigued to see that some deadening in the B pillar might also lend itself to helping the sound of the under-seat woofers too.

I used a silent coat style butyl on every section of bare metal on the doors under the vapour barrier and pretty covered the door card aswell. Did not use foam for the reasons above and just used butyl based. I would definitely try to deaden the underseat suns if could fit it in. I also used some in the bare metal areas in the boot around the rear shelf speakers.

Front & rear doors and some in the boot. You have me thinking about the sub enclosures now could be my next job.

Mine has been fitted for 3 years with no issues