BMW X3 Forum
BMW X3 Forum
Welcome to the ultimate BMW X3 community.
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
XBimmers | BMW X3 Forum BMW X3 and X4 Forums | F25 (2011 - 2017) | F26 (2014 - Current) Second Generation BMW X3 (F25) General Forum Cabin noise reduction - simple steps

Post Reply
 
Thread Tools Search this Thread
      10-19-2016, 02:09 PM   #1
supernova1
New Member
10
Rep
21
Posts

Drives: 2013 X3 x28i
Join Date: Feb 2016
Location: Connecticut

iTrader: (0)

Cabin noise reduction - simple steps

I want to share results of my experiments with decreasing cabin noise for my 2013 X3 xDrive 28i. I wanted to avoid costly and complex procedures applying extra sound proofing onto entire car body reported numerous times in this forum. Instead, I tried looking for simple, cheap and efficient steps to reduce cabin noise level to a reasonable minimum.

General observation before I started this effort - X3 is relatively quiet car in terms of road and wheel noise – may be because I use Continental Pure Contact tires instead of stock RFTs. My biggest issue with cabin noise stemmed from high frequency noise that fills up the cabin as speed increases. This noise does not seem to have particular dominant frequency and is perceived as high frequency hum echoed inside the spacious cabin. I also saw no correlation of this noise level and the wind speed, and found no to very little effect of the moon roof window as well (experimenting with the moon roof shade). Side mirrors do not contribute to it. It is weakly related to the road noise, judging by the only slight noise change when car drives on different road surfaces or puddles. Noise does modulate well with the car speed.

Here are my steps:

1. Very careful cleaning of all window and door rubber trims/gaskets. I used Meguiar’s Professional rubber and vinyl cleaner, but imagine that there are other suitable cleaners. I paid special attention to cleaning inside the trim window channels, and inside channel pieces where window top edges jam into – they rely on very clean surface to provide air-tight seal. Those particular places were very dirty; I had to clean them several times. I also cleaned all molding mating surfaces of the car body, including bottom plastic trims. I checked the gasket/window alignment, and found no issue. Result – some noise decrease, especially from pass-by cars due to real air tight seal of the window and door.

2. Central pillars have very thin inside plastic panels providing no sound insulation. Tap on them – they sound like a drum, plus left top one sits right next to driver’s left ear. I gently removed those panels (top and bottom pieces) and found that the body pillar top area had a vertical set of ¼” holes, and one 1” hole. They are probably needed to allow air to escape during car body priming dip and for rear door hinge attachment. Pillar itself had no insulation inside, although the outer pillar surface seems to have a secondary sheet metal plate inside. I simply applied small square patches of Dynamat on top of each hole to seal them out. Result – slight decrease of the high frequency hum originated from the pillars; Now, the bottom of each pillar had a large opening for the belt tension mechanism, and this hole opens directly to the outside sheet metal sandwich. There is not much space left around the belt mechanism to apply any sound proofing - ideally I should have removed it, but repair manual suggested replacing the bolt after that – not a route I wanted to follow. Instead, I applied patches of self-adhesive 10mm-thick rubber mat (closed cell, aluminum foil lined) on the back of the bottom plastic pillar cover. It has a set of horizontal ribs that divide the surface into “compartments”. I carefully applied the mat pieces in those “compartments”, leaving just the bottom one empty – this is where car wires pass by. I did not modify the top pillar cover – it is too close to the side air bag. Result – substantial decrease of cabin hum.

3. I did not like how intrusive was the circulation air fan noise – perceived as air swishing. It was quite tiring and emitted directly into my face from the central air vents. So I removed the blower motor from its enclosure (procedure is described elsewhere), being careful not to damage the squirrel cage fan. The fan stayed on the motor shaft – I saw no easy way to remove it. I found that the fan motor main shaft was quite rusty. Although it was spinning freely, I cleaned the fan top bushing with throttle cleaner (being careful not to spray it on the plastic parts), and applied several drops of non-detergent Zoom Spout Oil to the top and bottom bushings (I know that there are several school of thoughts as to what oil to use there), and blew graphite brush dust off with compressed air. I also found that squirrel cage fan was made of awful plastic, and had many surface imperfections on it. I used a piece of 800 grip sand paper and very gently sanded the fan outside blade surfaces, checking that I removed all the imperfections to some degree, and then wiped the dust off with vinyl cleaner. Result – I still hear the fan noise, but it diminished greatly and it does not bother me as it did before. It feels like my fan modifications removed particular frequencies from the blower hum.

4. Rear hatch directional noise. Surprisingly, BMW designed the rear hatch stop light access plates (made of thin plastic) so, that they open directly to the rear stop lights made of thin plastic as well, and there is no sound proofing in those areas at all. I applied patches of Dynamat on the access hatch covers (back side obviously), and added a patch of light-weight rubber foam sheet sound insulation between each cover and the lights, leaving enough space to have access to the light bulb sockets. I tried to be conservative in applying sound proofing there, as motorized hatch does not need extra weight, otherwise it won’t open properly. Result – this was one of the most detrimental changes affecting the cabin directional noise level.

To sum up, procedure #1 is a freebie – it is a commons sense to keep car door and window rubber gaskets clean and conditioned;

Procedure #2 decreased noise a lot – the central pillar belt mechanism opening passes the outer sheet metal vibrations in the cabin easily. The opening is located very close to road to pick up road noise. Plus seam between front and rear door edges in that area has no rubber gasket, allowing wind/road noise to come to the central pillar surface;

Procedure #3 decreased blower fan noise a lot and it is no longer “harsh” – now I just do not notice it;

Procedure #4 was quite simple and effective to remove directional noise that came from back of the car.

My car cabin is much quieter now – but do not ask me about dB numbers! It is simply less tiring when I coast on the highway. Although residual hum is still there (window glass?) – I hope to get to the bottom of it one day and post updates. Side effect is that I can hear more engine noise when car accelerates – but this is one of the joys of owing a BWM!

Hope this write up will help those who are as sensitive to the car cabin hum as I am.
Attached Images
  

Last edited by supernova1; 10-21-2016 at 01:27 PM. Reason: Picture addition
Appreciate 2
      10-19-2016, 08:10 PM   #2
mge92
SPEED RACER
mge92's Avatar
United Kingdom
217
Rep
663
Posts

Drives: Range Rover Velar D300
Join Date: Jul 2012
Location: London

iTrader: (2)

Do you have instructions and images? / maybe meet up to help me do it to mine?
__________________
2013 X3 xDrive28i Carbon Black: Enzo Flash Tune | ER Catless DP | M-Sport | Black Nevada | Premium | Cold Weather | Dynamic Handling | Technology | Premium Sound | Head-up display | 310 M Wheels | Supersprint Quad Exhaust | Carbon Fiber M Interior | Carbon Tint | Coded | Euro Mirrors | Rear Fog Light | Stealth 9500ci Install |
Appreciate 0
      10-20-2016, 01:44 AM   #3
Tjalle
Major
163
Rep
1,259
Posts

Drives: X4 35i
Join Date: Mar 2014
Location: Sweden

iTrader: (0)

Impressive work. Congrats!

Since I could only hear engine sound - no exhaust sound -I did it the other way around.
I installed M Performance two-way exhaust system with flaps for Sport and Track modes.

Now I have no problem with any noise above my exhaust sound
Appreciate 0
      10-20-2016, 05:12 AM   #4
ninoo
Enlisted Member
5
Rep
34
Posts

Drives: 2015 x3 2.0d Auto
Join Date: Apr 2011
Location: Ireland

iTrader: (0)

Thanks Supernova for this interesting and detailed post. this is an area that I also feel needs to be improved . I will carry out at least two of your recommendations today ( window and door seal cleaning and rear hatch mods) and report my findings. I am very happy with my X3 LCI otherwise..

Note. I intend fit NRF Tires at next tire change.
Appreciate 0
      10-20-2016, 12:17 PM   #5
ninoo
Enlisted Member
5
Rep
34
Posts

Drives: 2015 x3 2.0d Auto
Join Date: Apr 2011
Location: Ireland

iTrader: (0)

Today I cleaned window seals as you described and added some insulating foam and tape around the hatch brake light fitting. I also opened the hatch tail light interior covers to find skimpy patches of sound insulation . I added insulation here also. I am just back from a 100 mile drive and I must say that the back of the car seems quieter.I know that this perception can be affected by hope and expectation.
It would be interesting if someone on this board who has access to a Sound Level Meter was prepared to carry out before and after measurements on the same road in similar weather etc.
Appreciate 0
      10-25-2016, 10:02 PM   #6
malicem3
Private First Class
17
Rep
139
Posts

Drives: 135i, F25 X3
Join Date: Feb 2012
Location: Colorado

iTrader: (0)

This is extremely helpful. Putting this on the to-do list.
Appreciate 0
      10-27-2016, 08:49 PM   #7
beats
Lieutenant
beats's Avatar
122
Rep
490
Posts

Drives: 2015 911 GTS
Join Date: Jun 2013
Location: Toronto

iTrader: (0)

subscribed. thx op!
Appreciate 0
      04-21-2018, 05:45 AM   #8
CKau
First Lieutenant
22
Rep
390
Posts

Drives: F25 xDrive 30D
Join Date: Sep 2012
Location: sydney, australia

iTrader: (0)

I drove an xDrive30d LCI to see what the road noise and performance was like. I was impressed by how quiet the car was, but I bought a used pre-LCI xDrive30d.

I couldn't believe how much noisier the 2013 F25 is compared to the LCI. So I used the tips in this thread.

I applied Dynamat over the tail lights and on the inside trim used to access the tail lights. There was no insulation whatsoever (compared to Ninoo whose LCI has skimpy insulation).

I also removed the C-pillar trim and applied dynamat to some holes. This is easy to remove. Open the hatch on the side of the boot area and undo the screw. Pull off the trim & you're done.

It was like night & day! This made a huge difference. No need for a sound meter as there is a clear improvement.

I took a slightly different approach with the B- pillar and put Dynamat only over the holes - including the gaping one at the bottom where the belt mechanism comes out. I didn't want to put too much added weight in the car. I also put some foam in there.... marginal result.

I will try applying Dynamat another time to the entire B pillar trim to see what happens, but I'm very happy with the result so far.
__________________
2013 BMW X3 xDrive30d
[Sold] 2013 F30 328i
Appreciate 1
      04-25-2018, 08:28 PM   #9
vestaviascott
New Member
vestaviascott's Avatar
0
Rep
11
Posts

Drives: 2012 X3 28i 6 cyl Space Gray
Join Date: Apr 2018
Location: Birmingham, Al

iTrader: (0)

Thanks for the write-up!

I'm definitely going to add this to my to-do list. Great share!
__________________
2012 X3 28i 6 cyl Space Gray. *Tech, *Sport, *Convenience, *Premium
Appreciate 0
      04-30-2018, 10:01 AM   #10
tracer bullet
Major
tracer bullet's Avatar
United_States
435
Rep
1,448
Posts

Drives: '11 135i , '15 X3 35i
Join Date: May 2011
Location: Saint Paul, MN

iTrader: (1)

Roughly how much Dynamat is needed? I see a number of different kits available. Is 10 square feet enough?
Appreciate 0
      05-03-2018, 10:44 AM   #11
marc x
Enlisted Member
3
Rep
48
Posts

Drives: X3 F25 stock
Join Date: Jun 2016
Location: SoCal

iTrader: (0)

Simple my a$$
Appreciate 0
      05-25-2018, 03:04 AM   #12
CKau
First Lieutenant
22
Rep
390
Posts

Drives: F25 xDrive 30D
Join Date: Sep 2012
Location: sydney, australia

iTrader: (0)

Update: I use a self adhesive D shaped foam extrusion and stuck it on the front edge of both rear doors. The purpose was to close the gap between the front and rear door on the lower half of the door. The upper half is already sealed by BMW.

HUGE difference!

If someone can point me to a site where I can store photos to link to here, I'd be happy to share photos.

Then the next day I applied self adhesive audio foam, rather than dynamat, to the inside of the B-Pillar and eliminated the remainder of the noise.

What road noise that was remaining sounded like it came from the rear. So I applied the audio foam to that tinny plastic cubby in the boot floor that's on the rear right of the boot (trunk in US English).... the road noise has practically gone!

So the car is now as quiet as my parent's Skoda Octavia which is an awesome result... not quite as whisper quiet as a Golf Mk6 or Mk7.

I suspect if I did the B-Pillar for my F30 328i I would have been happy to keep the car. I got rid of it because it was so noisy... the F25 X3 is already much quieter than the F30 3 series out of the box.
__________________
2013 BMW X3 xDrive30d
[Sold] 2013 F30 328i
Appreciate 0
      05-25-2018, 04:47 AM   #13
cypis007
Private
Poland
0
Rep
81
Posts

Drives: E91 318d Touring
Join Date: Nov 2011
Location: Capital

iTrader: (0)

Quote:
Originally Posted by CKau View Post
If someone can point me to a site where I can store photos to link to here, I'd be happy to share photos.
https://postimages.org
Appreciate 0
      06-16-2018, 04:26 PM   #14
tracer bullet
Major
tracer bullet's Avatar
United_States
435
Rep
1,448
Posts

Drives: '11 135i , '15 X3 35i
Join Date: May 2011
Location: Saint Paul, MN

iTrader: (1)

Did the portion between the front & rear doors today. Have not done the trunk area yet nor have I driven it yet. But I thought I'd share some notes on the panels.

* The upper panel between the doors: Remove it by popping out from the bottom. Get your fingers between the upper and lower pieces and pull towards the inside of the car, away from the sheet metal. Once the bottom of that panel pulls out, just pull the whole thing downwards. The belt will be running through it but if you sit in the back seat you can apply the material to it.

* The lower panel is much the same but in reverse. It comes out second. You can see down inside and see the same connectors. Just get your hands down in there and make a fist and rotate and it'll come. I got it pulled most of the way into the car and did what I wanted (about 75-80% of it), I didn't go the last step and completely remove it.

* Moving the front seats all the way forward will help.

* Put things together slowly and in the reverse order. Make sure the plastic guys line up with their holes. Pull the gasket material out and around the panels before final pounding them into place. If things are lined up and the gasket's not in the way, give them a good hit with your fist over top of each of those connectors. Be sure of the above though, or you'll start breaking things.

* Be careful w/ the gasket when you get it back over the panels, if you run your fingers around there too quickly you could get cut on the panel itself.

* Smash that dynamat (or competitor) down, within reason of course. I used a roller, a trim panel remover tool (stiff and rounded), and my hands WITH tight fitting leather mechanic gloves on. If it's not stuck it won't do the job.

Hope to get to the rear soon, tapping those panels lightly tells you very quickly how loud they could vibrate in the right conditions.
Appreciate 0
      06-20-2018, 10:06 AM   #15
tracer bullet
Major
tracer bullet's Avatar
United_States
435
Rep
1,448
Posts

Drives: '11 135i , '15 X3 35i
Join Date: May 2011
Location: Saint Paul, MN

iTrader: (1)

Did the trunk, finally. I went a little further and took out all the panels from the tailgate. Started at the top of the window, then the sides of the window, and finally the bottom big one. All use the same push-in connectors as the pieces from the middle of the car. I put on some leather gloves and went around very slowly lifting and prying as close to the connectors as I could. The only tricky piece is the wiring to connect to the buttons that close the tailgate. Have a small flat bladed screwdriver handy, there's a small space that you can put it into and rotate to push the connector out.

I did put some sound deadener on the panels, including the pieces over the tail lights that pop out. In my opinion though, while that might have been important, I think there were a few additional or bigger areas of concern:

* The top most piece above the window is very light and buzzy. I added some deadener to it but also put some foam on it, very soft stuff from Home Depot for windows. Soft is the key, the heavy stuff even if thin won't flex enough and might make the panel tough to put back in or make it want to pop back out. This helped keep it from vibrating against things to begin with.

* The side pieces, at their tops, have holes where the connectors for the top panel go through. I put a little foam around those holes as well. This should help keep some gentle force on them, also to help keep them continually pressed against the window and less likely to vibrate against it.

* The large bottom panel didn't need much overall but the key area for it was the top of it (where it touches the bottom of the window). I concentrated the sound deadener here and added some foam as well. This is the area of the panel that, for me, really vibrated a lot.

I would suggest that you tap your panels with your fingers all over the place and figure out where they are noisy and hit other objects (i.e. the back window). Then when you take a panel off, have a good look and make a plan of attack for helping space those two things apart.
Appreciate 0
      06-20-2018, 10:32 AM   #16
x3sm
Private
6
Rep
72
Posts

Drives: X3
Join Date: May 2018
Location: CT

iTrader: (0)

Quote:
Originally Posted by tracer bullet View Post
Did the trunk, finally. I went a little further and took out all the panels from the tailgate. Started at the top of the window, then the sides of the window, and finally the bottom big one. All use the same push-in connectors as the pieces from the middle of the car. I put on some leather gloves and went around very slowly lifting and prying as close to the connectors as I could. The only tricky piece is the wiring to connect to the buttons that close the tailgate. Have a small flat bladed screwdriver handy, there's a small space that you can put it into and rotate to push the connector out.

I did put some sound deadener on the panels, including the pieces over the tail lights that pop out. In my opinion though, while that might have been important, I think there were a few additional or bigger areas of concern:

* The top most piece above the window is very light and buzzy. I added some deadener to it but also put some foam on it, very soft stuff from Home Depot for windows. Soft is the key, the heavy stuff even if thin won't flex enough and might make the panel tough to put back in or make it want to pop back out. This helped keep it from vibrating against things to begin with.

* The side pieces, at their tops, have holes where the connectors for the top panel go through. I put a little foam around those holes as well. This should help keep some gentle force on them, also to help keep them continually pressed against the window and less likely to vibrate against it.

* The large bottom panel didn't need much overall but the key area for it was the top of it (where it touches the bottom of the window). I concentrated the sound deadener here and added some foam as well. This is the area of the panel that, for me, really vibrated a lot.

I would suggest that you tap your panels with your fingers all over the place and figure out where they are noisy and hit other objects (i.e. the back window). Then when you take a panel off, have a good look and make a plan of attack for helping space those two things apart.
Nice!

Anyway way you can post pictures of the pieces you are talking about or maybe circle them on a random photo from google?

Also, what soft material from Home Depot did you use? I was thinking if stuffing some soft type material between the B-pillar and plastic trim.

Thanks
Appreciate 0
      06-20-2018, 10:50 AM   #17
tracer bullet
Major
tracer bullet's Avatar
United_States
435
Rep
1,448
Posts

Drives: '11 135i , '15 X3 35i
Join Date: May 2011
Location: Saint Paul, MN

iTrader: (1)

The #7 piece - I put the deadener material across this surface to help add some mass to it, lower the vibration frequency. I put some foam across the 2 long edges as well to help try and keep it pushed slightly away from where it attaches.

#6 piece - this is the area that really needs help, circled. I added foam around it as well (the opposite side of it as seen in this pic - the side which faces into the cabin and which panel #7 pushes against).

#3 panel, the big one, this is the area that for me needed the most work. That upper portion, especially what looks like the very light gray line in the picture, where it touches the glass, was the worst offender. I added deadener to most of the lower side of it especially over some "ribs" which you can see when the piece is off, these ribs help support it away from the metal int he tailgate. I got the deadener as close to the edge of this part of the panel as possible without extending beyond it so I wouldn't be able to see it once installed. A little foam around here too. It seems to have either given enough mass or spaced it slightly away from the glass and doesn't hit it any longer.

Each car might be different but this was the biggest area for me.

Overall I used less than 10 square feet of material throughout the car, so I'd say that's about the right amount to order.

I don't know how much improvement it made, but the car is dang quiet inside on the highway right now. It was always pretty good and I didn't pay a ton of attention before I started so I don't have a good baseline. The loudest thing is a little wind noise around the driver's door, maybe between it and the rear door. I'll have to look again at the seal and see if it's clean and flexible.

Oh, the foam - it was left over from a project and I don't know exactly what it was, sorry. I'd just look through their selection, you want something that is dense & thick enough to do the job, but not so dense or thick that you create new problems. Give them a squeeze between your finger tips int he package, if you can easily compress it to under 1/8" or so you're probably good, if it's a lot of work try another one. It just needs to provide a little, but not a lot of force.
Attached Images
 
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -4. The time now is 12:43 AM.




xbimmers
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST