Solarstorm

After some trial and error on upgrading to a frameless rear-view mirror on my UK spec S6 Avant C7.5, I thought I’d share the information in case it is useful for others.

TLDR, which mirror do I need;

• If you have the triangular module housing a camera on the windscreen, you want 81A 857 511 K
• If you don’t have the above module and have a straight piece of trim from the mirror to the headliner, you want 3G0 857 511 AD 9B9

Can’t speak to if you have the HBA camera directly behind the rear view mirror; but this thread maybe of help.
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For my car, there are 3 pieces of trim, the main surround for the rear-view mirror, the adjoining piece and the triangular (ish) section that covers the front facing camera. It’s the combination of these and using mirrors from different cars which caused the biggest headache.

I originally went with the 3G0 857 511 AD 9B9 as it is bigger than the 81A 857 511 K (Skoda Superb vs Audi A3 as the donor cars). However, as I have the triangular module on the windscreen, the trim on the 3G0 mirror doesn’t line up with the remaining A6 trim.

As the 81A mirror’s trim does line up with the A6 trim, I did try it on the 3G0 mirror, but it has a larger metal bracket and the 81A’s trim doesn’t fit.

Credit to Dawid from here; it is the 81A 857 511 part number for the mirror that is needed if you have the front facing camera like I do. Specifically, you’ll want the K revision, so it has automatic dimming (so 81A 857 511 K).

• Make sure if you’re getting a used mirror it comes with the plastic cover over the metal bracket. There isn’t a separate part number for this cover, so they’re a pain to get hold of separately!

Credit to back13a6 here, if you just have a straight piece of trim from the rear view mirror up to the headliner, you need 3G0 857 511 AD 9B9 for the mirror. Must be the AD revision in order to come with the 6 pins needed for side mirror auto dimming. The 4 pin AC revision can be used if you don’t have auto dimming side mirrors.

Audi Logic

Question for those that switched to the frameless mirror. 3G0 857 511 AD 9B9 has 4 metal prongs and the original mirror only has three, how did you guys get the 4-prong mirror to fit the mount on the windshield. Also what did you do with the small module located under the bottom cover on the stock mirror?

Solarstorm

What do you mean by 4 metal prongs? Do you mean the pins within the connector for the electrics or the 4 clasps around the circular(ish) part of the mirror mount that rotates and locks to the rain/light sensor 'hockey puck' glued to the windscreen?

If you have a small module under the bottom cover of the stock mirror, is this a front facing camera? Should be an obvious lens on it, something like this https://a.allegroimg.com/s400/03f5aa...UDI-A6-A7-Lift
If this is what you have, I've linked a thread that may help in my post above, but it's highly likely you need an entirely different mirror.

Audi Logic

I'm talking about the 4 clasps; my mirror only has 3 of them in a triangle configuration. As for the module, it's not a camera as there is no lens. I did a search and it appears to be a humidity sensor.

Solarstorm

I've not seen a 3 clasp mount for the rear view mirror on the C7 platform before, so not sure what to advise there.

Is the humidity sensor mounted to the windscreen (seen some translations of the rain/light sensor being described as a humidity sensor)?

Audi Logic

My rain sensor is mounted on the windshield. The humidity sensor is inside the base of the rearview mirror cover, the section with the vent holes. Audi must have changed the mount sometime in 2012 because I see both when searching online. Below is a pic of what mine looks like. I also have an extra pin in the connector.