OK, I now have the same problem. How did you solve this?

 

Ok so here's what I did after coming up with nothing from every source around: Black Permatex RTV adhesive.

Take a razor blade and windex and clean off any residue from the original install. Use blue painters tape and tape a flat area on a cutting board. Place the pot metal piece (flat side down) on the tape and cut an outline. Remove the inner piece you cut and discard. Take the remaining tape and carefully position it on the inside of the windshield so the hole is aligned with where the metal piece is. Smooth everything down. Lay a towel over your dash underneath just in case. Apply black RTV to the metal ring and position on the windshield. Hold in place for about a minute or two. I did this by myself, so if you have a spare set of hands it will be much easier. Take blue tape and tape the hell out of the metal piece to the windshield. Leave the car alone for awhile. I think I gave mine 2 days in the garage (in Arizona in the summer) just to be sure. Make sure to crack the windows to avoid storing up any fumes. Afterwards, remove the tape, trim any excess RTV off (especially in the middle) and make sure it's on there good. Now take your replacement rain sensor cover (the clear adhesive thing - which, btw, is the same as the Audi part ... The Audi one was a fraction of the cost of the Porsche one, go figure.) and apply it to the mirror assembly. Take the mirror and push it on to the ring. It takes a fair amount of force to snap on. I can't remember if there's a screw holding the mirror together or not. Voila!

Big thing - make sure you position the ring right side up. The repair is still holding up (as far as I know - sold the car in spring 2014). But even if it fails again, a tube of black RTV and a rain sensor sticker are a lot cheaper than a new windshield.

Sorry if the formatting is jacked up, I'm posting from my phone w/o tapatalk.

 

I wondered how window tint guys take the mirror off when they do a 3M tint?

 

Thanks av8bpilot. Following your instructions I have the metal ring adhered to my windshield using Permatex Black Adhesive Sealant, covered with tape and curing. I'll try to track down the rain sensor adhesive next. Hopefully it holds up as well as yours did. Thanks again!

 

Maybe someone who's actually done this will eventually get back to you. In the meantime this is one of those jobs where prep is everything. You'll want to remove old glue residue from any parts you're reusing, windshield or mirror.

 

Basically this. If memory serves, there wasn't really any residual glue on the mirror assembly itself. All of the glue seemed to remain on the glass. That's where the razor blade came in handy. Reach out if you have any other questions. It was a while ago, but I still remember the repair. I'll dig around to see if I still have the pictures, since it looks like they're gone from the site.

edit - no go on the pictures.

 

I just came across the same problem, and thank you for you post, because it was the right solution. However, since the OPs pictures are gone I'll add new ones, it took me quite a bit of figuring out without those. I have the auto dimming mirror with rain sensor, for other mirrors these instructions are probably wrong.

After popping off the two beauty cover pieces, unplug the plug at the bottom, then slide the mirror down off the metal ring and then separate the rain sensor from the ring.

This is the ring, facing the inside and in the correct position (top/bottom)

The rain sensor and the plug

The mirror itself, with the metal clamp that grabs the grooves in the ring. This slides down from the ring.

This is the RTV silicone used. I got it at AutoZone, but any of the usual parts stores seems to have it.

Unlike the OP, I didn't tape up the windshield. I simply applied the RTV directly to the glass facing side of the ring, it needs to be thick enough to make it past the lip on the ring, then held it against the windshield and had a helper tape it up so it would stay and cure. I let it cure for about 24h before I re-assembled it all back together.

The ring, all taped up.

The next day I applied the rain sensor pad on the rain sensor and clipped the rain sensor back into the ring. I didn't buy the pad from Porsche, or Audi, but instead found a universal 'Rain Sensor Gel Pad' on Amazon (~$5), cut it to size (a 1 in circle) and used that. My rain sensor works perfectly.

Then I slid the mirror back onto the ring from below, plugged in the cable and clipped the beauty cover back on.

Mirror slid back on the ring.

 

@earlster - great job for a first post! I'm looking forward to more well done and illustrated posts from you. You're well on your way to being award a technical contributor award!

Meanwhile - can I bug you to introduce yourself and your Porsche. We have a place made just for doing that.. https://www.planet-9.com/forums/new_members/

It's traditional for the new member to post a few photos of their Porsche, so we can go ooooohhhhh and aaaaahhhhh! over it.

Welcome to Planet-9, the Friendly Porsche Forum that appreciates a well-done tech posting!

 

Thank you SO MUCH for your post. Same thing happened to me and I am in the process of following your guide.

One question: there is a black material on the other side of the ring (that faces the windshield) adhered to the metal. Should I cut that off (razor blade + sandpaper) before applying the RTV?

 

Yes, remove all that foam/rubber and clean it up well, then use the Permatex.

 

Thank you for the quick reply!

 

Thanks to everyone's help I was able to successfully complete this repair. I did take the step of creating the tape "mask" (with a hole cut out for the metal ring), which helps in more easily removing excess RTV, but it's not absolutely necessary as the RTV is pretty easy to remove after it hardens.

A few more photos of intermediate steps in case it helps anyone.

Prepping the windshield by removing residual material.

Some of what flakes off when you prep the windshield

Tape mask

Tape mask on windshield:

The windshield-facing side of the ring with all the old black adhesive material cut off / sanded away.

RTV applied generously to the ring.

 

A huge thank you to everyone that posted on this project. I can confirm that this process also works on a 2008 911 C4S with auto-dimming. The most difficult step for me was trying to understand where the connector in the wire harness is positioned, to allow the clamshell pieces to close. Because it fell out so quickly when I was taking things apart, I never really saw how it was positioned inside the unit. After much ado, I figured out that it slides inside a small opening that is kind of horizontal with the top of the dashboard. Once it pushes inside this opening, there is nothing of it sticking out and the clamshell pieces can be snapped back together. I hope this helps others.