Trunk/Cabin Sound Barrier

[archsteve]

Since I got the car in December, I've noticed road noise coming from the trunk area - this seems to have gotten louder since my Toyota track day a few weeks ago (I am assuming the rubber build up on tires/ tire wear/etc is the temporary cause of that). So I ordered some sound insulation for the trunk floor, reasoning that this was closest to the source and except for that thin insulation on the trunk floor mat, there was nothing separating the road noise from the cabin. The insulation I got after a bit of internet research is standard 2 part foam sound deadening sheets (80mil layer and a 157mil layer). Current plan is to install that tomorrow pending the weather.

While I was waiting for it to arrive, I wondered if anyone had ever tried building a separation barrier between the cabin and trunk - it is kinda odd to see inside the hatch/trunk area from the cabin, and since its my daily driver I have a few tools/work supplies back there that I don't really want to see/hear. The only similar thread I saw on the forum was a fabric/leather drape right behind the seats, so here is my prototype/mockup that I'm experimenting with this weekend that is a more rigid version.

Similar thread from 2021 : https://www.supramkv.com/threads/ha...and-hatch-cargo-area-ever-been-produced.7795/

The white foam board was a 1/4" thick leftover marketing board from the office - the longest dimension is 38" +/- so a standard 2'x4' foam board from office depot should be ample. I cut it to fit the interior dimensions up against the back of the speaker box area, then back cut it vertically so the board would bend and allow it to be slipped in place. Tomorrow's plan is to apply the sound insulation to the rear face, then wrap both sides with an $11 roll of black car carpet from O'Reilly's. Not planning on attaching it permanently, the friction fit seems fine in the test, especially with the anticipated carpet thickness added to it.

Any suggestions/constructive criticisms welcomed, especially if someone has tried this before or if anyone has insight on the 80mil and 157 mil sound sheets from experience?

Sponsored

 

[Loco38SUP]

Since I got the car in December, I've noticed road noise coming from the trunk area - this seems to have gotten louder since my Toyota track day a few weeks ago (I am assuming the rubber build up on tires/ tire wear/etc is the temporary cause of that). So I ordered some sound insulation for the trunk floor, reasoning that this was closest to the source and except for that thin insulation on the trunk floor mat, there was nothing separating the road noise from the cabin. The insulation I got after a bit of internet research is standard 2 part foam sound deadening sheets (80mil layer and a 157mil layer). Current plan is to install that tomorrow pending the weather.

While I was waiting for it to arrive, I wondered if anyone had ever tried building a separation barrier between the cabin and trunk - it is kinda odd to see inside the hatch/trunk area from the cabin, and since its my daily driver I have a few tools/work supplies back there that I don't really want to see/hear. The only similar thread I saw on the forum was a fabric/leather drape right behind the seats, so here is my prototype/mockup that I'm experimenting with this weekend that is a more rigid version.

Similar thread from 2021 : https://www.supramkv.com/threads/ha...and-hatch-cargo-area-ever-been-produced.7795/

The white foam board was a 1/4" thick leftover marketing board from the office - the longest dimension is 38" +/- so a standard 2'x4' foam board from office depot should be ample. I cut it to fit the interior dimensions up against the back of the speaker box area, then back cut it vertically so the board would bend and allow it to be slipped in place. Tomorrow's plan is to apply the sound insulation to the rear face, then wrap both sides with an $11 roll of black car carpet from O'Reilly's. Not planning on attaching it permanently, the friction fit seems fine in the test, especially with the anticipated carpet thickness added to it.

Any suggestions/constructive criticisms welcomed, especially if someone has tried this before or if anyone has insight on the 80mil and 157 mil sound sheets from experience?

This is what reduced the road noise on mine.

https://www.supramkv.com/threads/is-your-exhaust-a-little-too-loud-try-this.22895/post-365947

-RJM

 

[BMWAF]

Any suggestions/constructive criticisms welcomed, especially if someone has tried this before or if anyone has insight on the 80mil and 157 mil sound sheets from experience?

It's, umm.. very aesthetically displeasing.

 

[SupraYYJ]

It's, umm.. very aesthetically displeasing.

It could be worse. A trunk full of manure would be more effectively acoustically and arguably less attractive. Arguably.

 

[BMWAF]

It could be worse. A trunk full of manure would be more effectively acoustically and arguably less attractive. Arguably.

Not sure this changes my original statement but OK.

 

[Ron L]

Since I got the car in December, I've noticed road noise coming from the trunk area - this seems to have gotten louder since my Toyota track day a few weeks ago (I am assuming the rubber build up on tires/ tire wear/etc is the temporary cause of that). So I ordered some sound insulation for the trunk floor, reasoning that this was closest to the source and except for that thin insulation on the trunk floor mat, there was nothing separating the road noise from the cabin. The insulation I got after a bit of internet research is standard 2 part foam sound deadening sheets (80mil layer and a 157mil layer). Current plan is to install that tomorrow pending the weather.

While I was waiting for it to arrive, I wondered if anyone had ever tried building a separation barrier between the cabin and trunk - it is kinda odd to see inside the hatch/trunk area from the cabin, and since its my daily driver I have a few tools/work supplies back there that I don't really want to see/hear. The only similar thread I saw on the forum was a fabric/leather drape right behind the seats, so here is my prototype/mockup that I'm experimenting with this weekend that is a more rigid version.

Similar thread from 2021 : https://www.supramkv.com/threads/ha...and-hatch-cargo-area-ever-been-produced.7795/

The white foam board was a 1/4" thick leftover marketing board from the office - the longest dimension is 38" +/- so a standard 2'x4' foam board from office depot should be ample. I cut it to fit the interior dimensions up against the back of the speaker box area, then back cut it vertically so the board would bend and allow it to be slipped in place. Tomorrow's plan is to apply the sound insulation to the rear face, then wrap both sides with an $11 roll of black car carpet from O'Reilly's. Not planning on attaching it permanently, the friction fit seems fine in the test, especially with the anticipated carpet thickness added to it.

Any suggestions/constructive criticisms welcomed, especially if someone has tried this before or if anyone has insight on the 80mil and 157 mil sound sheets from experience?

That's an interesting idea. I can't say that I really noticed the road noise in my 2025 Supra. It's so much quieter than my 2021 Miata RFB was. But I do kind of like the idea of making the back area separate from the cabin. Let us know how well you think this works.

 

[Andrew4Supra]

I’m curious to see the end result of your project. Keep it going…

As you mentioned in your thread… the leather cover divider I designed made the difference I was looking to achieve. My primary goal was to hide items stored in the hatch from my peripheral vision while cutting down on the road noise.

 

[exe36m3]

I made that original post (like others) about adding sound material in the trunk using known material. The divider/baffle should work but for me, I like keeping things tidy and out of sight.

I first did the sound material on the floor of the trunk to lower exhaust drone. Effort got me a noticeable decline in muffler and road noise. But once I insulated the battery compartment, there was a further decrease.

If you want to further reduce road noise, consider pulling the panels behind the seats and using sound deadening material as I believe the rear shock towers are another source.

 

[Ron L]

I made that original post (like others) about adding sound material in the trunk using known material. The divider/baffle should work but for me, I like keeping things tidy and out of sight.

I first did the sound material on the floor of the trunk to lower exhaust drone. Effort got me a noticeable decline in muffler and road noise. But once I insulated the battery compartment, there was a further decrease.

If you want to further reduce road noise, consider pulling the panels behind the seats and using sound deadening material as I believe the rear shock towers are another source.

Excellent info and suggestions. Thanks!

 

[archsteve]

That's an interesting idea. I can't say that I really noticed the road noise in my 2025 Supra. It's so much quieter than my 2021 Miata RFB was. But I do kind of like the idea of making the back area separate from the cabin. Let us know how well you think this works.

Day 2 of the sound/cabin barrier experiment. Took several steps to get it where I'm happy enough with it to see how it performs on the commute tomorrow.

On the cabin side of the barrier I put a soft layer of sound/thermal insulation I had saved from some packaging a while back. I intentionally used a compressible material that will abut the speaker box so I can get a good fit there (even with my poor craftmanship on this prototype). I am skeptical on the actual amount of sound deadening/blocking that this layer will provide, but it gives me a good substrate for the cabin-facing carpet to sit on and being so compressible I can use it to seal any air gaps.

On the trunk side of the barrier I placed a layer of Siless 80mil sound sheeting then a layer of the 157 mil sheeting. Both of these were bought for my trunk floor and other metal panels to fight road noise (will install next weekend) but I figured they might contribute also as a sound absorber/deadener. Once again I'm skeptical that they will perform as designed as they are intended to mount on metal panels, not a foam board.

The final layer of sound insulation was some closed cell foam insulation that I had in the workshop - hoping this contributes also as an acoustical deadener but its been so long since college acoustics/physics class LOL.

The last layer was the carpet to cover all surfaces. I think its a decent match for the Supra carpet. You can see in the photos the slight crease in the carpet where the board/insulation was cut to bend it into place. I am assuming this crease will relax with time, but it also allows me to remove it easily if I need to .

Other than my time, this experiment cost $11 worth of carpet at O'Reilly's with everything else (foam, spray adhesive, etc.) being stuff I had in my workshop. Looking forward to seeing how the car sounds this week under various driving conditions and whether I will keep this experiment or try something different. Appreciate the comments and suggestions received to this point.

 

[Jnhalstead]

Hurts to see Siless go into a Supra, it might be the worst product on the market. It is known to melt. Butyl rope in seams, some fibermat and some mass loaded vinyl will yield some pretty good results. Also removing the liners and putting material on back side and on chassis will help. Resonix has a website full of useful info if you want to go down a rabbit hole

 

[archsteve]

Hurts to see Siless go into a Supra, it might be the worst product on the market. It is known to melt. Butyl rope in seams, some fibermat and some mass loaded vinyl will yield some pretty good results. Also removing the liners and putting material on back side and on chassis will help. Resonix has a website full of useful info if you want to go down a rabbit hole

Appreciate that advice - first time trying any of this so its all been an experiment

 

[tonymimi]

Just curious have you considered a switching to a quieter tires? You already add some sound deadening panel highly doubt if there are many headroom for the additional improvement. Supra is already quite quiet out of the box.

 

[archsteve]

Just curious have you considered a switching to a quieter tires? You already add some sound deadening panel highly doubt if there are many headroom for the additional improvement. Supra is already quite quiet out of the box.

I have had that thought, when its time to replace the OEM tires that came with it 5 months ago. Thanks

 

[FLtrackdays]

Just need to get the AWE track exhaust with catless downpipe. Then you’ll never hear tire or rear trunk noises ever again ?

Sponsored