Noise reduction rear areas

[mike123abc]

The TX highway department seems to love a cheap noisy overcoat for asphalt roads that was driving me crazy, so I decided to rip out the back of the car and do some soundproofing:


To do this I watched the youtube video:

I took out the rear seat backs (4 nuts) so that I could completely take out the liner which wraps under the seat backs. It really was not that hard to take it all out. I just took time to note where I got each of the fasteners from so I could put it back later.

As you can see in the pictures, Tesla does put some sound dampening material around the inside. They also have some padding on the back of the liners which looks like it would help dampen noise:


I got some dynamat: https://www.amazon.com/gp/product/B00020CB2S/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

and a dynapad: https://www.amazon.com/gp/product/B001KM5IZO/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

I proceeded to use 7 of the 9 sheets in the package. I decided to save a couple of sheets for the front if I ever get around to it.

The first three sheets I applied to the driver's side wheel. Note you can reach quite a ways around the wheel. Tesla had some material on the inside, I did it behind:


Then I took out the sub woofer and amplifier assembly on the passenger side. I did not disconnect the wiring:


I only used 2 sheets on the passenger side since I did not want to apply it around the sub woofer. I was afraid it could dampen the sound of the woofer. Looks like I hit a forum picture limit and will have to add another message to continue!

 

[mike123abc]

Well the first post has some issues but there was only a 10 minute time limit to edit it, so it is as it is.

Here is what the passenger side looks like:


As I mentioned I did not do around the corner the sub points at, so only used 2 sheets.

Then I wrapped a couple of spots on each side with the 6th piece and then put the rest in the inside:

 

[mike123abc]

Then I put in a 7th sheet:



Note that I did not cover any holes, or fasteners. I also did not bother putting over Tesla's material.

Then I put in the Dynapad: I was lazy and did not cut it, it pretty much just fit in place pretty good. I did not adhere it either, it is just held in place by gravity and the liner:


I then put the car back together. I had to work a bit to get the trunk well all the way in with the dynapad, but was able to get it all to squish into place:


I put back in the seats and it was all back together.

 

[mike123abc]

I took sound measurements from 5 different sections of interstate/highway to test it out ran 77MPH on autopilot:

Smooth fresh asphalt: Before 66-67.5 After 64.5-66 -- I would say about 1.25 to 1.5 dBa difference on average
Regular asphalt: Before 70.5-72.5 After 68 - 70.5 -- I would say about 2 dBa difference on average
Cement Interstate: Before 72-74 After 69.5 to 71 -- I would say about 2.5 dBa
Rough asphalt: Before 80 to 82 After 75 to 77 -- I would say about 5 dBa
Super bad overcoat: Before 85-86 After 78-79 -- roughly 7 dBa

This is a picture of the super bad overcoat. It is the noisiest section of road I know. It is a 75 MPH speed limit road, seems like they put down gravel and then misted some tar on top to hold it in place:


The Project time took about 4 hours (one person). Cost $249.

It will not help quite roads, but it really helps noisy ones. Now all the noise seems to come from the front of the car now. I suppose I will eventually apply my last 2 sheets on the front of the car.

 

[Runnergirl]

That's a lot of work. I just turn the music up!!

 

[saltsman]

Super helpful. I'm about to embark on the same process. The road overcoat process is officially called Chipseal whereby the contractor lays down a heavy coat of tar and then distributed crushed aggregate over it (aka. Tar and feather). Not only is it loud, it also causes accelerated tire wear and increased rolling resistance. It's inexpensive for TXDOT, but cost you more in tire replacement, energy loss, and your sanity.

(PS. Do the people who post to "just turn the music up" also suggest tossing on some perfume in place of a shower? Just wondering... )

 

[-DA3]

(PS. Do the people who post to "just turn the music up" also suggest tossing on some perfume in place of a shower? Just wondering... )

**LOVE THIS!!!!**

 

[bradhs]

Buy a pair of AirPods and put them in your ears. They block the higher frequencies and you can still hear exceptionally well with them in your ear. (This may be against the law.)

I like the Dynamat idea.

When you took the car apart and put it back to together. Did you break any of the clips? If so, which ones? I want to buy extra clips so I have them handy.

 

[alexGS]

Super helpful. I'm about to embark on the same process. The road overcoat process is officially called Chipseal whereby the contractor lays down a heavy coat of tar and then distributed crushed aggregate over it (aka. Tar and feather). Not only is it loud, it also causes accelerated tire wear and increased rolling resistance.

Most of our roads in NZ are made like this, probably due to relatively low traffic volumes and the desire to maximise traction in the wet. The other PITA with this method is the loose, scattered stones left there after the overcoat for a few weeks; all it takes is a truck coming the other way, and a stone flies out of nowhere into the windscreen.

I intend to beef up the sound deadening as well, especially with the dB differences reported here - I’ve done this with other cars and been happy with 2dB improvement. Won’t help the tyre wear or stone chips though

-Alex

 

[alexGS]

It will not help quite roads, but it really helps noisy ones. Now all the noise seems to come from the front of the car now. I suppose I will eventually apply my last 2 sheets on the front of the car.

Thank you for taking the time to share this with us!

I understand from reading elsewhere that the next thing is to remove the front trunk liner and apply sound deadening to the front strut turrets?

-Alex

 

[saltsman]

Buy a pair of AirPods and put them in your ears. They block the higher frequencies and you can still hear exceptionally well with them in your ear. (This may be against the law.)

When traveling alone, I often use a Jabra noise canceling headset and play audiobooks/music through those. If stopped, I'll call it my hands-free device .

The issue I have is when traveling with others. The road noise on worn concrete or chipseal is so loud, we can't talk to each other without shouting.

The National Institute for Occupational Safety and Health (NIOSH) has recommended that all worker exposures to noise should be controlled below a level equivalent to 85 dBA for eight hours to minimize occupational noise induced hearing loss. When traveling on chipseal, the Model 3 can exceed that limit. FWIW, adding louder music would only elevate that noise level.

 

[saltsman]

Thank you for taking the time to share this with us!

I understand from reading elsewhere that the next thing is to remove the front trunk liner and apply sound deadening to the front strut turrets?

-Alex

And around the four non-visible sides of the Frunk tub and to the underside of the Trunk carpet...

 

[mike123abc]

I still have a couple of sheets of they dynamat for the front, but have just been too busy with life/work to try to figure the front. Anyone have insights on the best front of car treatments? I would buy more sheets if needed.

Really the rear has been such an improvement that I have not been so intensely motivated to fix the front of the car. Getting it below 80dba has really helped keep my sanity. My normal drive keeps me at 30 minutes or so a week on the insanely noisy road.

What is bad is that I rode as a passenger on the same stretch of road in an ICE vehicle and it seemed quieter than my Tesla with the rear treatment. It was a chevy car, not a luxury one! It seems that one area the model 3 skimps in is factory noise control. They could pretty easily put some of the factory noise control substance in more areas to really reduce the noise.

 

[mike123abc]

It's inexpensive for TXDOT, but cost you more in tire replacement, energy loss, and your sanity.

I wore my first set of 19" tires down to 4-5 at 16k miles... I guess TXDOT is at fault! And yes driving 75 MPH over it drives energy usage up over 300 watts per mile.

 

[polyphonic54]

Great write up! Do you know how much weight the treatment added to the car?

 

[mike123abc]

The shipping weight of the dynamat and dynapad was 30 pound (15 pounds each). I saved 2 sections of the dynamat to do the front wheel wells, so just under 30 pounds I would say.

 

[polyphonic54]

Not bad at all considering the reduction you were able to get. Those chipseal roads in Texas are just brutal, especially on 75 mph roads.

I really hope later Models (or even the Y) start to come with better noise insulation that we might be able to copy.

 

[alexGS]

Don’t want to be critical but I just had a thought - how about using the Dynapad cut to shape in the rear wheelarches (behind the ‘carpet’ liners which aren’t very dense)? The metalwork is basically naked here.

Just thought maybe the heavy pad might absorb tyre noise close to the source. I was surprised how superficial the wheelarch carpet seemed to be.

-Alex

 

[bradhs]

This sounds like a great idea because less noise will also hit the frame. Instead of dealing with the noise later on you're dealing with the source. Brilliant.

Don’t want to be critical but I just had a thought - how about using the Dynapad cut to shape in the rear wheelarches (behind the ‘carpet’ liners which aren’t very dense)? The metalwork is basically naked here.

Just thought maybe the heavy pad might absorb tyre noise close to the source. I was surprised how superficial the wheelarch carpet seemed to be.

-Alex

 

[PNWLeccy]

@mike123abc I'm working on the trunk area right now and I have a question about the square clip at the top where the rear seat side bolsters clip into. They look like they need to be removed to get the side of the trunk felt out. I also broke them when removing the side bolsters. How did you handle that clip/area?

Also did you do behind the trunk lid as well? I found the area very difficult to apply sound dampening to because of the narrow holes in the sheet metal which was super sharp. Also broke most of the blue clips there