what do I do about this birdcage rust?

[Randall K.]

Started disassembly last Friday to work on HVAC, and discovered this in the upper corner on the passenger side.

HELP!

Thanks
Randy

[Doug F.]

Re: what do I do about this birdcage rust?

randy, SEM makes a product called rust seal # 39304, brush it on and it turns black, seams to neutralize it pretty good, then just forget about it, the next 40 years on your car should be much kinder than the first 40.

[Jim T.]

Re: what do I do about this birdcage rust?

Randall from viewing your picture you can make temp cosmetic repairs but that is all you would accomplish.

How much water leakage do you have on the passenger floor? Does the #2 body mount location have rust?

There is so much information in the archives on what you may encounter to fix your 72. The good news is that the replacement/repair parts are being reproduced so you do not have to search to find donor parts and GM does not have the parts available anymore.

I repaired my 70 with new parts from GM in 1986 and did not have the rust you show on the inside. The picture you show is the inside of a part of the birdcage assembly that has a external top layer of metal that is the windshield lower corner frame. There is a void between the two layers of this manufactured part.
Actually from the factory the upper/top piece has a hole in it that is under (not viewable) the fiberglass support piece mounted to it.
This fiberglass support is between the upper portion of top of fender below the lower corner windshield and can allow water to come on in.

Even the new GM replacement part I bought in 1986 has the hole. Welded it closed.

Other than rusted through windshield frame, this hole is a path for water to come in.

If you or a windshield shop/body shop would remove the upper windshield molding you can inspect this area of the windshield frame as well as the sides.

Repair of the opposite side of your pictured rust area will require removal of some of the top fender.

[Chuck S.]

Re: what do I do about this birdcage rust?

I agree with Jim...the only way to really repair this requires welding.

Once you expose the outside of the windshield frame, you will probably find the area of the frame right below the corner of the windshield rusted through. On mine, the rest of the sheet metal looked sound except that localized area, so I cut out the rust thinned metal, and pounded out a piece of similar gage plate to fit a butt welding patch for the opening. It was tricky because the top edge of the patch actually forms the step where the glass fits...no room for error. The bad news is the windshield has to be removed, with all the risk of breakage, to make a welding repair.

[Randall K.]

Re: what do I do about this birdcage rust?

Doug/Jim/Chuck - thank you for your replies. I had a chance this morning to take a quick look at the #1 and #2 body mounts on the passenger side, and I'm pleased to tell you that they only have minor surface rust that you'd expect to see after 37 years. Absolutely no through-and-through rust like what I saw below the windshield frame.

I'm hoping to have the time over the weekend to take a look at the driver side to see if I have the same problem over there. This will be the first time for me to try to remove the driver side console/dash...

Any further advice is welcome!

I'm thinking that this will become a winter project, as I really just want to get my HVAC system finished and get on the road!

Randy

[Harmon C.]

Re: what do I do about this birdcage rust?

With the products made today you can clean up and epoxy small holes. If the repair is large then welding in new parts may be the way to go. Body shops today epoxy on beds on pickup trucks and very little welding do I see when I vist a shop I use often.