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From digest.v6.n338 Sun Mar 9 20:41:50 1997
From: "Gregory J. Bradbury" <>
Date: Sun, 9 Mar 1997 12:13:44 -0500
Subject: Rear defroster repair.


Bill McMahon of San Francisco wrote about re-attaching the rear defroster clip back on the glass of his '87 535is after being broken off. I had the same problem on one of my cars when I bought it (used). I work at Caterpillar and we have a group called Caterpillar Service Technology that takes care of developing and suppling shop supplies, standard tools and special repair tooling and test benches to our dealers worldwide. I asked them since they have good access and relations to 3M, Loctite, etc.

There are a multitude of repair products for sealing, repairing cracks in the glass, painting the grid lines back on, etc, but NONE (you can prove me wrong) to "glue" the contact back. I have NOT been able to find an electrically conductive glue.

It was recommended to me to simply and carefully re-solder it back. First, put some sort of protective cloth on the package shelf to protect the carpet from falling bits of hot solder. Remove the clip that normally is part of the windshield from the wire / harness. Put some electronic flux in a tube (Radio Shack would be a good place to buy this in the US) and applie it to the clip and rear window contacts.

Hold the clip with a small set of needle nose pliers and use a soldering iron (30 watts) to heat it up and apply solder to the contact face (you almost need three hands but it CAN be done). You then use the soldering iron to press the clip up against the glass to melt the flux on the glass and heat up everything to make the bond. This last part should be done in just a few seconds to avoid damage to the glass and (most importantly) the contact metal that is chemically bonded to the glass. Remove the soldering iron, keeping the needle nose pliers in place to hold the clip until the solder cools (about 5 seconds).

I managed to get this right the first time, but I've been soldering electronic circuit boards for 15+ years. From what I hear, a good practice exercise would be to re-solder the new batteries in your dash SI boards (only kidding a little). Seriously, it DOES work. You should be careful when you then reattach the connector to the male connector that you just resoldered. Then drive, defrost and enjoy.

Gregory Bradbury
1981 M535i (e12)

GM makes a kit. It retails for ~$15. It is called a "Rear Window Defogger
Repair Kit". Part Number 12345345. Group Number 8.800.

Loctite also makes one. Part Number 15067. They call it "QUICK GRID Rear
Window Defogger Repair Kit".

From digest.v7.n764 Sun Dec 14 12:40:46 1997
From: (Dan B Zeitlin)
Date: Sun, 14 Dec 1997 08:17:31 EST
Subject: Rear Defogger Repair

Loctite makes a kit called "Quick Grid Rear Window Defogger Repair Kit" that contains a small bottle of conductive acetate(?) and a throw-away brush. I think it costs about $5. Works well. [ed Part Number 15067.]

Dan Zeitlin, Annapolis, MD
BMW CCA #67431

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