Decel noise, need ideas.. C7 S6

[Twkdcd595]

Hello,
So I am trying to isolate a decel noise that resembles a tire rubbing a fender liner screw (changes with the speed of the vehicle) but more metallic sounding. Think of like a heat shield rattle sound but speed based and only on decel from like higher rpm to 1500-1800 ish rpm. It is fairly loud and you can hear it with the windows down very clearly or even in the car faintly.

It is driving me nuts and I am newer to this platform so I thought I would post up for ideas. I know a 'what is this noise' thread is tough to help with but didn't know if something like this is common. I tried searching through other threads and coming up with nothing.

It is not a tire rubbing and same sound regardless of ride height. Car is on hre ff01 wheel with a fresh set of 265/35/20 tires so nothing crazy for tire fitment or wheel to brake caliper clearance. Braking also does not change the sound other than it slowing with the speed of the car so I don't think its like debris/ rock in the brake situation.

ETA: Google drive video link below.

[RAF_S7]

A recording of the noise may help......

[Gwillplays]

Let’s do some isolation. If you have the convenience, try putting your stock wheels back on and see if the problem persists. It may sound weird, but my stock wheels make my car whisper quiet and my CVTs make a noise on decel. No clearance issues. Go figure. My second set of after market wheels, with different offset make no noise. Same manufacturer of wheels. Hit me back with test results. Maybe we can solve this together.


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[Twkdcd595]

I will try to get a buddy to ride along so I can capture the noise tomorrow. I thought about doing it but driving and recording seemed like a bad idea. Plus with a passenger I should be able to get a much cleaner recording of it.

[nick1980]

I had a weird noise on my 2012 A6
noticed on decel I had a odd "heatshield" raspy noise only at 1500rpms
It would do it while warming up and idleing down
In gear ,park etc.
Ended up being broken down cats /broken cat flange rubbing .
Sounds different than your description but never know

[Twkdcd595]

I just took a short drive to the corner store to try to record it (beer run you could say) and it didn't happen... very strange. Seems to almost be only an issue when the car has been running for a while.

[esemes]

Let’s do some isolation. If you have the convenience, try putting your stock wheels back on and see if the problem persists. It may sound weird, but my stock wheels make my car whisper quiet and my CVTs make a noise on decel. No clearance issues. Go figure. My second set of after market wheels, with different offset make no noise. Same manufacturer of wheels. Hit me back with test results. Maybe we can solve this together.


Sent from my iPhone using Tapatalk

if the wheels are a possible variable, def try this!

[gk1]

Oh and pics of the HRE FF01's with 265/35/20 tires. Thanks.

[Twkdcd595]

Oh and pics of the HRE FF01's with 265/35/20 tires. Thanks.

Excuse that it is not actually clean, it would be if it was not supposed to rain tomorrow. Snapped a couple pictures when running to gas station (quick stop and jumped out so suspension probably not leveled) and seeing if that noise would happen again. Could not capture the sound as it only happened faintly and Audi insulation is quite good at muffling it to the point in car while driving it is hard to accurately record.

https://media.discordapp.net/attachments/606159927114989589/612668498602098700/20190818_100809.jpg?width=807&height=455

https://media.discordapp.net/attachments/606159927114989589/612667799336255707/20190818_100745.jpg?width=491&height=873https://media.discordapp.net/attachments/606159927114989589/612667753945628672/20190818_100708.jpg?width=491&height=873

[Twkdcd595]

Finally got quality clip of it after a number of attempts... this is windows up in car with my phone recording sitting on the passenger floor mat and later me holding it just above the passenger floor mat. I had it set super sensitive to sound so everything is a bit exaggerated but seems to pick it up clearly.

It is not a tire I am 99.9%... turning the wheel, ride height raised/ lowered (factory air), hard or soft braking does not matter, and tire is showing no rub marks or indications of contact. A local dealer (had it in for an oil change so I could talk them out of the warranty records which they provided) was like eh its probably brakes cause you are do for front brakes in the relatively near future. I find it hard to believe it is brakes since it does it regardless of how you brake or not braking at all though.

Its like a plastic or light metal scratching on something relative the speed sound. Thinking heat shielding rubbing something but I have limited room in my garage right now thanks to let a friends park a car for a short time so I cannot easily move my other car in the garage. Need to get it jacked up and take a look under it to see if anything is obvious.

Anyone experienced similar?

https://drive.google.com/open?id=1-NsxAIM3MgUde6fpJlImDXLDTrFcY5Tb

[cW6mT mKviGLi]

Before I heard the video clip I was going to say that it sounds like you had the same problem that my C7.5 A6 had. However, after hearing the clip it sounds similar to cards flapping around in bicycle wheel spokes. My issue sounded similar but was alot more muffled and can only be heard with the windows down and if I alongside another car or wall barrier. The sound would reflect off the other surface and would be heard around 1500rpms and only on deceleration.

My issue ended up being the flex section in the factory downpipes. When Audi did the warranty work the new downpipes had a revised flex section.

Good luck with the solution.

Sent from my SM-G965U using Audizine mobile app (http://r.tapatalk.com/byo?rid=87676)

[Twkdcd595]

Before I heard the video clip I was going to say that it sounds like you had the same problem that my C7.5 A6 had. However, after hearing the clip it sounds similar to cards flapping around in bicycle wheel spokes. My issue sounded similar but was alot more muffled and can only be heard with the windows down and if I alongside another car or wall barrier. The sound would reflect off the other surface and would be heard around 1500rpms and only on deceleration.

My issue ended up being the flex section in the factory downpipes. When Audi did the warranty work the new downpipes had a revised flex section.

Good luck with the solution.

Sent from my SM-G965U using Audizine mobile app (http://r.tapatalk.com/byo?rid=87676)

Mine is similar in the way it happens but yea more like a scratching like something contacting another surface and making the noise. Similar decel around 1500 rpm condition at lower speeds only and outside the car it is louder/ reflected off the driving surface.

I have Redstar downpipes coming for the car so I guess I can make the excuse I needed them to make sure that was not the problem... totally justified upgrade now!

[Twkdcd595]

I still cannot find the noise and it is driving me kind of insane. Makes me feel like I am driving a clunker when I have rattles and that obviously is not true but mentally it takes something away from driving/ enjoying the car.

Checked brake rotor shields, brakes for debris or something (doing fresh brakes in the next couple weeks), heat shielding around the exhaust/ driveshaft in the tunnel, front sections of splash guards checked for rub marks (doubtful they would make the noise with the dampening material they have on them), cleaned out all the rocks and bits of crap in the front bumper splash guard, checked the inner fender liners for rub marks, removed the 12 oclock screws for good measure (although does it even with suspension in lifted position, etc.

I received my downpipes so I will do those in the near future but brake light just went on so that will take priority.

Hopefully I find something when doing the brakes but those far I am at a total loss. You would think there would be some indications of wear someplace and even in time it would clearance whatever was rubbing.

[headbang]

[tylersund72]

Were you ever able to figure this out? I am having the exact same issue on my c7 s6 and have been unable to successfully diagnose it.