Major RUST prevention in corners.

[swanny11]

So im replacing the back corners on my 47 chevy cab, and damn near every cab i have seen on craigslist has rusted out corners (Thanks Washington). I understand parking it in a dry area will help tremendously but im just curious if you guys did anything special to your corners before replacing them...
I was thinking about putting a couple layers of POR-15 on the inside then sealing it up.
Thoughts?
-Jess

[Donaldo]

""I was thinking about putting a couple layers of POR-15 on the inside then sealing it up. Thoughts?-Jess""

I don't think making a sealed frog pond feature in the corners is a good idea - your already going to fix them because of that -

After the replacement of the corners I put a drain hole out the bottom of each corner, and then bed linered the insides, I think air circulation is better than having moisture and 'stuff' built up in the corners. I used a 2 part bed liner product for D'Angelos supply. Cut and cleaned up with acetone, set up hard in a couple hours. The POR-15 would probably do well also - I have not used it.

[swanny11]

Yeah that does make more sense haha. I like the idea of the drain hole though! Thanks

[Ratpin]

I personally would not use POR15 in that area unless you opened it up first and applied it open.

Once you replace the corners or get the cavity ultra clean soak it with ospho or a similar product, rinse it very well, force it bone dry with air or heat and then spray in plenty of Amber (cavity wax) this should keep the moisture off the metal.

[roger55]

I believe Por15 is over-hyped and isn't a product to consider for automotive use. Great for metal furniture though.

A good epoxy primer seals metal just as good if not better than Por15. And, offers several advantages.

[dwcsr]

Paint them and don't let dirt and junk collect in them.
All the corners I've replace all have has a wad of dirt or a rag or something else that collects moisture. None are painted from the factory, seal the seams from the under side.

[Northern lights]

If you are going to "paint" it with anything to prevent rust, I think this should be your first consideration http://www.rustbullet.com/?source=ad...JlQaAr208P8HAQ . Do some research on it and i think you will be pleased with what you discover.

[Donaldo]

""None are painted from the factory, seal the seams from the under side""

In other words it was designed to eventually rust out.

Perhaps if they knew then what we know now.......

[OrrieG]

Probably very few of the designers, engineers and folks building these anticipated they would still be on the road in 10-20 years, let alone 50-60. On TF the open inside corners are an invitation to rust. I cringe at all the times I just hosed mine down after a muddy weekend camping or hunting to find later all the drain holes were plugged up. I covered the inside corners and made sure there are generous drains between the inner and outer panels below. Some issue with the lower door hinge pocket area. Most do not know there is a metal flap with a screw to gain access to that area to clean in out and allow drainage. Dirt, leaves, etc get in from the cowl vent.

On mine I cut out the bad rust to good metal, used POR-15 system on remaining areas, then used single stage chassis paint. On the exposed underside of cab, corners and bottom of firewall I used rattle can rubberized undercoating over the paint. I noticed that part of my truck had originally been undercoated and those areas (it was pain to remove to metal) did not have any of the surface rust issues the exposed painted areas did.

[dwcsr]

Originally Posted by Donaldo

""None are painted from the factory, seal the seams from the under side""

In other words it was designed to eventually rust out.

Perhaps if they knew then what we know now.......

Seam sealing and coatings to prevent corrosion and rust weren't in the picture back then. I don't think its a designed to rust out situation but rather not designed with rusting out in mind. The more of these I take apart the more I see just how badly the were designed and built.

[roger55]

Car and trucks really weren't designed to last but about 5 years before rust-out was expected.
They wanted you to buy new again and customers didn't demand better.

Very much different nowadays.
Remember back to the 70's when Japanese cars were better in this regard than American cars. That's when things really started to change. It was sad at the time to see American cars lag behind.
Not anymore though. Things have totally changed. Parts are made all over the world and assembled all over too. Car designers are all mingled up. It's a global market now.

[Big Daddy Bear]

I read on another thread that someone made some sheet metal "covers" for that area. After repairing the bad spots, a piece of sheet metal was cut to match the cab contour and welded in place.

Thought was, it would protect the area from accumulating things/dirt that would just start the rust process all over. I was thinking of the same thing, except, after fixing/replacing what is necessary, spray the area with some Rustolem type rattle can paint just to cover clean metal, then after welding the new floor cover on, filling the empty space with expandable foam spray.

That would completely fill the void and remove any air pockets and not add any kind of weight.

Overkill???

[Old Crow]

I've seen people use that spray foam in trunk drop offs and cab corners. Sounds good in theory, but moisture will still get into the foam, and then the foam itself holds the moisture against the inside of the panels.
When we do cab corners, we coat the inside with POR-15 after we're done and make sure there is drainage from the cavity. Blocking the top of the cavity to keep leaves and such out would help to insure the drain holes stay open.

[_Ogre]

if the original cab corners were kept clean they wouldn't have rusted
most had mud packed in there and a few rags or old forgotten t-shirts stuffed in there

keep the drain holes and mud pack out of there and you shouldn't have any problem
of course primer and paint helps too

[swanny11]

Sweet! thanks for all the input guys
Pic of progress. I just got done with replacing the seam piece on the back of the cab.

[fourspeedwagon]

I was always under the impression there was a guy, who's job it was, to pour a cup of saltwater into the cab corners as these trucks left the factory?

My DRY, desert (it's whole life) original paint '51 GMC even has some rust in the corners. We get less than 8" of precipitation a year and my truck lived not far away for it's life. There's pretty much no hope for finding one without rust I assume.