Solved: Rattle from rear deck

[B9RS4.SedanNow]

A lot of people experience rattle in the back of the B9 S4 and B9 A4 saloons.

There is a TSB about the speaker grills over the sub, but it’s actually not the speaker grills rattling in most cases.

Audi actually can’t fix your problem because they don’t know what causes the rattle. I know because they tried with my car and failed.

Fortunately, this has driven me so crazy that I finally figured it out and fixed it.

I share this with you to hopefully save you some frustration, but any modifications you make to your own car you do so at your own risk.

All of the rattling in my case came from the third brake light housing. There were in total three types of rattles coming from this third brake light housing: mounting clip rattle, interface rattle, and internal rattle.

1. Mounting clip rattle: The loudest and most annoying of the rattling is from contact between the small metal mounting rail glued to the glass (green arrows) and the metal spring loaded retaining clips (red arrow). You can see the two metal on metal wear lines in the photo on the bottom surface of the metal mounting rails.

Despite being very annoying, this rattle is intermittent so it’s the hardest to pinpoint.

To quiet this rattle you need to place a thin peace of felt tape on the under surface of the mounting rail so that it insulates the spring loaded clip from the mounting rail.

Some cars have plastic mounting rails. If you have plastic rails you don’t need to do this.

IMG_7304.JPGIMG_7300.jpgIMG_7306.JPG

2. Interface rattle: This is the second loudest rattle from the third brake light housing, and it comes from contact between the plastic and the window. To quiet this rattle you need to put felt tape on all the points of contact with the window (yellow lines).

IMG_7296.jpg

3. Internal rattle: This rattle is the most subtle and hardest to fix. However, this is also the most constant rattle. It comes from contact between the LED circuit board and the lens. The lens is ultrasonically welded to the housing so you can’t really get to the board to fix this easily. To fix this I drilled holes in the top of the lens behind the LED circuit board and partially filled the cavity behind the board with hot glue. I put one whole hot glue stick through each hole (white arrows).

IMG_7302.jpg

I hope this guide helps someone with their rattles.




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[jonesey]

great write up and yes you are correct..I guess it's dealership dependant because my dealer knew exactly what it is was first go round, thankfully. They also added some dynamat i had laying around to the speaker deck.

[z_wrecker]

Great Job and thank you for the write up. I've had my car less than a week and haven't noticed any rattle just yet. I do have a good chunk of dynamat xtreme left and would like to put some on the rear lid and possibly the doors. My b7 had such a solid sound when the doors closed. This car feels little more hollow. I like the satisfying THUD when the door is closed :)

[AWDYEAH]

Just now having this issue, thanks for the write up.


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[AWDYEAH]

Forgot to report back. I added the felt tape on the metal tabs on the third brake light and it took care of my issue. The light is a bit of a pain in the ass to get out the first time. Get the panel removal tool and be patient and it’ll come out.


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[awdconnor]

I used felt and double sided tape on the black plastic part that lays on the window. Worked like a charm

[Goblues39]

Just developed this rattle in my 2019 S4.....is the black housing and/or light assembly easy to get off? I really don't want to go to dealership for this.....

[S4James]

i had some wire harness tape that i put on just the leading edge and that was sufficient for now. 7 Nation Army turned my car into a vibrating horror show thanks to that.

[Ejr]

A lot of people experience rattle in the back of the B9 S4 and B9 A4 saloons.

There is a TSB about the speaker grills over the sub, but it’s actually not the speaker grills rattling in most cases.

Audi actually can’t fix your problem because they don’t know what causes the rattle. I know because they tried with my car and failed.

Fortunately, this has driven me so crazy that I finally figured it out and fixed it.

I share this with you to hopefully save you some frustration, but any modifications you make to your own car you do so at your own risk.

All of the rattling in my case came from the third brake light housing. There were in total three types of rattles coming from this third brake light housing: mounting clip rattle, interface rattle, and internal rattle.

1. Mounting clip rattle: The loudest and most annoying of the rattling is from contact between the small metal mounting rail glued to the glass (green arrows) and the metal spring loaded retaining clips (red arrow). You can see the two metal on metal wear lines in the photo on the bottom surface of the metal mounting rails.

Despite being very annoying, this rattle is intermittent so it’s the hardest to pinpoint.

To quiet this rattle you need to place a thin peace of felt tape on the under surface of the mounting rail so that it insulates the spring loaded clip from the mounting rail.

Some cars have plastic mounting rails. If you have plastic rails you don’t need to do this.

IMG_7304.JPGIMG_7300.jpgIMG_7306.JPG

2. Interface rattle: This is the second loudest rattle from the third brake light housing, and it comes from contact between the plastic and the window. To quiet this rattle you need to put felt tape on all the points of contact with the window (yellow lines).

IMG_7296.jpg

3. Internal rattle: This rattle is the most subtle and hardest to fix. However, this is also the most constant rattle. It comes from contact between the LED circuit board and the lens. The lens is ultrasonically welded to the housing so you can’t really get to the board to fix this easily. To fix this I drilled holes in the top of the lens behind the LED circuit board and partially filled the cavity behind the board with hot glue. I put one whole hot glue stick through each hole (white arrows).

IMG_7302.jpg

I hope this guide helps someone with their rattles.




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Thanks for this. But my rattle comes from the speaker grills over the sub on the rear dash. I know this cause when I placed my hand over them, rattle stopped. What’s the fix for that?