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Spittybug
12-24-2018, 04:01 PM
This is the continuation or "while I'm in there" of this thread: http://dmctalk.org/showthread.php?16957-Door-alignment-and-striker-questions

Aligning doors led to checking roof boxes and so on.....CHECK THEM!!While I had no outward signs of problems I discovered that I tackled this in the nick of time.

Remove louvers and the plastic trim piece so you can get to the torsion bars.
Remove T panel.
With an assistant, open doors fully (remove struts and keep open with rod) and while keeping tension on torsion bars, unbolt brackets. Read more about this elsewhere if you have never done it so that you don't smack your rear glass with the bracket and break it. You may need a shot of lube to slide the bracket off the torsion bar.
Remove access panel and disconnect electrical connectors. CLEAN THEM with a dremmel tool and sandpaper.
Remove 4 bolts from hinges into doors and remove doors - careful, heavy.
I cut a second access panel in my box which I will weld back into place when done. Just do it far enough from the ends to not be cutting where the boxes overlap.
Look inside in wonderment and all of the rust.
Use a shop vac and a strong magnet on the end of a retrieval tool or something else that you can fish around in there. The rust will stick to it and then just vacuum it off. Do this, a lot and get all loose rust out. If starting to penetrate sides of box, punch these out a bit to remove loose areas.
Use a rust neutralizer (I love the Metal Ready that works with the POR-15 paint) and SPRAY it inside, soaking everything. Slosh around with brush.
Come back half an hour later and do again.This is where I'm up to now.
Next step is to rinse and dry with a heat gun or hairdryer.Spray if possible, or paint in the POR-15 to encapsulate the now neutralized rust. This stuff loves water and gets harder when wet, thus encapsulating the rust and preventing any water from getting to the metal. Be liberal, but in thin coats.
Re-weld panel back. In my case I removed my hinges and found rust under them and all over the shims.


I have not yet gone through the process of realigning the doors which I understand can be fun, but I was careful to put scratches/notches/tape on the box to mark their location. I surmise that the biggest cause for this rusting is worn/missing top seals allowing water into the upper channel. That in itself isn't terrible, but I noticed that the corners of the "I" that the whole box assembly makes were slightly open!!! These little holes allow the water in the upper channel to get into the box. The factory RTV'd the hell out of the corners and around the hinge bolt holes, but with time (or sloppiness) these fail and water/humidity gets in and does its deed on the metal.When my box is sealed back up and the hinges remounted I will spray Flex Seal over everything to create a nice waterproof skin. Needless to say I have also put on new upper door seals which I notice are a bit longer than the ones I had on before.
Hopefully this keeps me good for another 35+ years!

David T
12-24-2018, 04:56 PM
The outer door seals at the top of the doors are not meant to be watertight. Their purpose is to keep most of the water out and what little bit gets past them is supposed to drain in the channel. There are a lot of ways for water to seep into the roof box, it was a bad design and once water gets into it the box rots badly. From the Service Bulletin that was issued (ST-33-12/81) you can see DMC had a lot of problems with water intrusion. It was the biggest SB of all. The best thing you can do is garage the car so it is not in the weather, then you don't have to worry about water intrusion and the car will last a lot longer, frame too.

Spittybug
12-26-2018, 06:55 PM
Ready for POR-15. Just drying the box out after rinsing away the metal prep rust converter. Shop vac is blowing air into the cavity and the holes are blocked off so that it forces the air out any rust holes or other places not visible. I used a spray bottle and a brush to get everywhere inside. Not easy.

When I go to seal everything after the rust painting, it has become apparent where the water gets into and under the roof box. Rather than globbing on the RTV like the factory did, I think selective filling around nuts/bolts and in the small holes is in order followed by a total seal coat of the Flex Seal. Volume isn't the answer, ensuring it is applied where needed CAREFULLY seems to be.

Spittybug
12-27-2018, 03:52 PM
POR-15 done. Messy stuff but I was able to get into all corners of the box using a bottle brush that had bristles on the end as well as sides. Also used a rag on the end of a stick to wipe things around. Checked with scope and I'm pleased with the coverage. One little can got used to give the entire box and the shims of the hinges 2 coats.
I welded (very ugly; I need more practice) the panel back in place and ground down the welds a bit. Next step is to mount the hinges and spray with the Flex Seal.