I went ALL IN on C-Pillar rattle

[Min Ahn]

Facts: 2019 Mustang Ecoboost Premium Performance Package 1 / 6670 Miles / Grandpa-like driving style / Rattle still exists



The rattle began 3-4 months ago (but the car’s purchased in May) in the rear passenger side and it’s getting worse day by day.



It’s frequently heard when I’m accelerating from stop, or braking to stop. Either way, I think the change in weight distribution of the chassis is actually triggering the rattle.

I did A LOT of research in the past few months and finally took an action today by taking interior panels apart.

I wish removing the plastic panels resolved the issue, but no luck. Which then led me to dig deeper and inspect the components that were hidden behind the trim, like pillar airbag or anything near it.

I then loosened the screw that was holding the airbag and shoved sound absorbing materials purchased from Amazon in between the bare metal of the body and the airbag with inner plastic stuff.

The test drive (with no trim panels as above) was disappointing and I gave up for today. Well at least I think I narrowed it down but don’t know what else is left to tackle. If it’s not the plastic trims or components that are attached on the metal, then what could it be?

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[gmupatriot]

Have you tried removing the rear deck-lid panel? I have noticed a buzzing/rattling sound from that area on my 2018 GT and I stuffed some material between the deck-lid and it got rid of most of the noise.

Good luck!

 

[Cobra Jet]

Is it truly a rattle - or is it more like a noisy squeaky noise, almost like styrofoam rubbing up against something?

Since your panel is off, can you reach into or see anything in the open cavities, to see if something is dangling around making the noise?

 

[Min Ahn]

Have you tried removing the rear deck-lid panel? I have noticed a buzzing/rattling sound from that area on my 2018 GT and I stuffed some material between the deck-lid and it got rid of most of the noise.

Good luck!

I haven't tried touching anything outside the cabin, but I will keep dismentling the car until I locate the issue. Thanks for the suggestion!

Is it truly a rattle - or is it more like a noisy squeaky noise, almost like styrofoam rubbing up against something?

Since your panel is off, can you reach into or see anything in the open cavities, to see if something is dangling around making the noise?

The video is uploaded now. The best way to describe the noise would be, that it's similar to what it sounds like when the license plate is touching the bumper if you know what I mean.

 

[gmupatriot]

I haven't tried touching anything outside the cabin, but I will keep dismentling the car until I locate the issue. Thanks for the suggestion!

Before you check anything on the outside, check the panel above the rear speakers as well. I have heard buzzing/rattling noise from that area and it could be the case with you since you have gutted everything else on that side of the car

 

[Min Ahn]

Before you check anything on the outside, check the panel above the rear speakers as well. I have heard buzzing/rattling noise from that area and it could be the case with you since you have gutted everything else on that side of the car

Are the rear speakers located under the rear windshield / on top of the headrest on this car? I haven’t seen any speakers on the side panels or b-pillar.

 

[gmupatriot]

Are the rear speakers located under the rear windshield / on top of the headrest on this car? I haven’t seen any speakers on the side panels or b-pillar.

This is the shelf/panel area I was referring to:

 

[Cobra Jet]

Hmmm... I’m not sure if your rattle may be this or not, but see below and attached link.

In the trunk - remove the trunk liner on that same side. Once it is removed, back by the taillight assembly on that side, there is a very thin sheet metal square that is spot welded to the top of the rear wheel well housing.

On that piece of metal is the rear BCM (and possibly another module), it’s secured to that thin piece of metal by (2) nuts.

On my prior 2016, that piece of metal would “flap” or rattle when going over bumps, road imperfections, etc. because of how thin it is and supporting the weight of the attached modules. Even though it’s in the trunk, it could still be heard in the cabin, with rear seats up too.

Here was my fix for my prior 2016 S550:
https://www.mustang6g.com/forums/threads/passenger-side-rear-1-4-rattle-how-to-get-peace.62664/

 

[GT 550]

Hey Min might be worth going for a drive with someone in the back seat to act a spotter?

 

[Min Ahn]

This is the shelf/panel area I was referring to:

Wish me luck tomorrow that speaker is going DOWN

Hmmm... I’m not sure if your rattle may be this or not, but see below and attached link.
In the trunk - remove the trunk liner on that same side. Once it is removed, back by the taillight assembly on that side, there is a very thin sheet metal square that is spot welded to the top of the rear wheel well housing.
On that piece of metal is the rear BCM (and possibly another module), it’s secured to that thin piece of metal by (2) nuts.
On my prior 2016, that piece of metal would “flap” or rattle when going over bumps, road imperfections, etc. because of how thin it is and supporting the weight of the attached modules. Even though it’s in the trunk, it could still be heard in the cabin, with rear seats up too.
Here was my fix for my prior 2016 S550:
https://www.mustang6g.com/forums/threads/passenger-side-rear-1-4-rattle-how-to-get-peace.62664/

Thanks for sharing this information. I too thought that if it's not the plastic trim noise, this will be it after reading through multiple reports on this BCM module. I saw some saying this was improved after 2018 models but one way to find out!

Hey Min might be worth going for a drive with someone in the back seat to act a spotter?

I agree but it's just me and the car for now... :(

 

[Min Ahn]

UPDATE

So today, I went ahead and dismentled more in the trunk and the rear speaker area.

First things first, the trunk liner was taken out and I did some inspection.

Whatever this cable is, was not attached to anything and was just dangling. I doubt if this fabricated cable would make any noise, but I taped it to the chassis anyway just to make sure. NOT LEAVING ANY DOUBT.

I took off the BCM module as

.

mentioned.
I was very surprised because this was attached to a very very thin FLAPPING metal.
Using the sound deadening pad, I put a thick layer of cushion between this plastic module and the sheet metal.

While I was at it, I noticed this piece of styrofoam thingy on the fender panel of the body. I guess Ford thought this is good enough to prevent outside noise coming into the cabin lol.

And like

.

suggested, I took off the rear speaker liner thing and gave an inspection. Unfortunately, there was no moving piece and the speaker was bolted down pretty hard that shaking it shook the whole car.


This is as far as I can go for today and I will give a test drive tomorrow on my way to local Ford to get my defective decklid panel replaced. I guess I'll tell them to solve the noise issue as well while I'm there.

 

[jbanh100]

UPDATE

So today, I went ahead and dismentled more in the trunk and the rear speaker area.

First things first, the trunk liner was taken out and I did some inspection.

Whatever this cable is, was not attached to anything and was just dangling. I doubt if this fabricated cable would make any noise, but I taped it to the chassis anyway just to make sure. NOT LEAVING ANY DOUBT.

I took off the BCM module as mentioned.
I was very surprised because this was attached to a very very thin FLAPPING metal.
Using the sound deadening pad, I put a thick layer of cushion between this plastic module and the sheet metal.

While I was at it, I noticed this piece of styrofoam thingy on the fender panel of the body. I guess Ford thought this is good enough to prevent outside noise coming into the cabin lol.

And like suggested, I took off the rear speaker liner thing and gave an inspection. Unfortunately, there was no moving piece and the speaker was bolted down pretty hard that shaking it shook the whole car.


This is as far as I can go for today and I will give a test drive tomorrow on my way to local Ford to get my defective decklid panel replaced. I guess I'll tell them to solve the noise issue as well while I'm there.

Lmao I laughed so hard at the little piece of styrofoam thingy. I thank you so much for doing this, I was on the merge of insanity with my rattles but some days it goes and some days it comes back. I REALLY HOPE YOU CAN FIND THE SOURCE. It makes me love my car again when all I can hear is the exhaust note and not just jingles and rattles D:

 

[Min Ahn]

So unfortunately that last attempt didn’t solve the issue. The noise is still there and I don’t know what else to do lol.




I just found this video that best replicates the sound I am hearing in my car. I’m gonna put it on the jackstand and see if the noise is coming from the same sourse.

 

[TicTocTach]

Subscribed, I have the same issue in my 2018 EBPP and have been unsuccessful in fixing it as well. Haven't gone as far as you have, but I have had a rear seat passenger that locates the rattle near the air bag canister as you noted. FWIW, that passenger is my 11-yr-old son, who's not fully invested in solving the problem but is very aware of the rattle when he sits back there on road trips.

I did find the same issues you noted on the thin metal tab in the trunk, but although I think my repairs there helped, it wasn't the main problem.

 

[Condor1970]

I did similar to mine when I decided I wanted to upgrade my speakers. I put sound deadening foam all over the side panels, door panels, fender well, and trunk lid, etc. I also sprayed the inside of the outer door panel sheet metal with a thick layer of Flex Seal clear to deaden road noise....

....The C-pillar still rattled when I was done. I was so discouraged. Stereo sounds great though.

Finally, I just took that C-pillar panel off again, and injected insulation foam behind the air bag mount and all the plastic panel mounts behind it that the clips are installed into. Basically I just filled every gap along the C-pillar with foam until it was oozing out, and trimmed off the excess when dry.

The spray foam I used, finally killed the C-pillar rattle.

https://www.amazon.com/Loctite-TITE...ocphy=9033456&hvtargid=pla-453093435814&psc=1

Btw, behind that little flimsy panel in the trunk?? I just shoved a cheap $3 standard bed pillow behind it to fill in that whole area to deaden sound, and keep it from rattling.Works great.

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