So. Why do these truck rust so bad in the cab floors....

[Zumo]

...in the cab corners and such? How is the water getting in and how can we prevent it? Could I drill a drain hole in each corner and rocker?

[ebfabman]

Zumo, I think its a combo of several things. First the factory didn't get the inside of the rockers, cab corners, cab supports, A pillars, cab roof, etc coated with anything to prevent bare metal from being exposed to the elements. Other things include the nature of the design of the lower part of the cab leaves several "cavities" for moisture and trash, etc to get "trapped" holding the moisture, and not dry out very fast. Another thing I've noticed especially at the cab corner, in cold weather, when the heater is on and the inside of the cab is warmer than the outside air causing a condensation situation which leaves moisture to collect in the lower cab area. Factor in a salty mist into the mix and wala... a great recipe for oxidation aka known as our hated enemy RUST. Another thing is these cabs have a LOT of places for water to leak into them. 30+ year old dried out, cracked up seam sealer, makes a leaky cab. Anyway, this is my theory and I'm stickin to it

BTW, I have coated inside the areas mentioned above with epoxy primer and paint with a modified wand and pressure pot set up . Works real well. I can post some pics if you like

[Grim Reaper]

I'm with EB after putting a couple back together.

GM installed the rust at the factory. almost no rust preventsion. Litterally take bare steel make a truck out of it and run it thrrough a paint booth. There is not even any paint inside the rocker cabvities and door frames. It's just raw metal.

[ebfabman]

"GM installed the rust at the factory" HAHAHA......LOL

Good one Reaper, I think you are absolutely 100% correct!!!

Thats why I kinda laugh when I see......." complete rust free cab"..... well maybe somewhere.......

[me3]

I have two trucks im fixing one was an old fertilizer truck. and the other is an old farm truck but the farm truck is rusted out worse then the other wierd?

[botboy]

My truck was equipped with a special factory rust option that is printed on the glovebox door. Super rare ++, give me money!!!

I just can't wait to see the ebay auctions...

[TEXAS 68]

I guess that explaines this

[Zumo]

I know right. Seems like a lot of these trucks rot from the inside out.


BTW Thanks ebfabman.

[69 Short Fleet]

Mine has just started to rust about 1" above the drivers side sun visor (a small 1/8" hole) and I'm gonna have to adress all the cavities in the cab with some sort of rust check to stop this from getting out of hand! I'm kinda freaked about what its like behind the windshield rubbers now. I was thinking of pulling the sun visors and spraying something in that area first! Doug

[junkyardjohn]

[QUOTE=ebfabman Thats why I kinda laugh when I see......." complete rust free cab"..... well maybe somewhere.......[/QUOTE]
BELIEVE IT OR NOT.. THERE ARE SOME RUSTFREE (MEANING .. NO RUST AT ALL EVER) TRUCKS OUT HERE IN THE DESERT. MATTER OF FACT THERES ONE IN MY GARAGE. IT'S NOT THE FIRST RUSTFREE 67-72 TRUCK I'VE DONE. BUT THEY'RE GETTING HARD TO FIND & EXPENSIVE. I PAID $3800 FOR THIS TRUCK & DROVE ABOUT 1050 MILES TO GET IT IN MY OLD TOWTRUCK. IT WAS A PILE OF PARTS WITH NO FRONT CLIP ON IT. EVERY ONCE IN A WHILE YOU'LL RUN ACROSS A TRUCK FROM THE FOURTIES OR FIFTYS THAT ARE STILL RELATIVELY RUSTFREE. . JOHN

[ebfabman]

John, believe it or not it was you I was thinking about when I said "....somewhere"

[junkyardjohn]

YEP.. IT'S KINDA NEAT FINDING THEM, BUT THERES AN AWFUL LOT OF RUSTY TRUCKS HERE TOO. I LIKE TO THINK THAT THEY ALL MIGRATED HERE. JOHN

[Southpa]

Not only cabs, have a look at the wheel well tub bolt channel on my 70 GMC.

[Robert1970C20rstbukt]

Originally Posted by TEXAS 68

I guess that explaines this

That's the same problem with mine, 'cept it has some bondo hiding it. Sometime I'm gonna grind out all the rusted stuff and weld new sheetmetal in. Right now I put more bondo on it to cover the holes since I can't do any metal work right now. Not smart, but who cares. This used to be a farm truck, but it's still used like one, and the floors aren't really bad. Both the bottom kickpanels are rusty, not bad. The floors are rusted on the outer edges about a inch and a half. The inner floorboards, tranny tunnel, and area under the seat have NO rust at all, just the original dk olive paint.

[TP from Cntl PA]

Yeah, lots of rust on the iron around here. I use the Fiberglass filler for now too. Although the K-10 will have 100% new metal put it. Actually, the only reason I am going to paint my C-20 is to help it last for acouple more years. It seems like every year they come out with more replacement metal pieces and hopefully they'll have firewall pieces by then.

Boy, if a company could ever make a new cab for these trucks people would line up for them

[1BadSS]

Originally Posted by me3

I have two trucks im fixing one was an old fertilizer truck. and the other is an old farm truck but the farm truck is rusted out worse then the other wierd?

nothing weird about it, mud gets up in there and sits forever.

[Huck]

Not hard to figure out once you look around----notice the holes in your dash top on the corners near the glass---one on each side> They were predrilled at the factory to allw the leaking windshield to channel the water away from your radio speaker. In fact the drivers side routes the water onto your fuse panel. The drip rail on the roof is designed to hold water there as a tank to filter the water into your windshield frame and it works fine even with the calking/sealer they used. Cab corners were designed to hold old rags and beer cans which in turn captured all sorts of moisture and in time will rot out the metal. Rocker panels have an access hole in the front of them to allow spraying in undercoating which in turn fills the drain holes to allow moisture buildup and quick rust out. Pretty effective designs when you think about it~~~!

[Zumo]

Pretty good Huck.

[Southpa]

ALSO, if you pull your cowl you should see tiny drip rails on either side to channel water towards the open area at the rear of the fender. Those little drip rails on my truck are long gone. If they installed screening under the cowl slots at the factory to stop all the leaves, nuts, fruits and bugs then they might still be there. When I first checked about 6 yrs ago I pulled out handfuls of compost from either side of the under cowl area.

[MrGoodpliers]

As mentioned earlier, the windshields are prone to leak, right down to the kick panels (which are just seam sealed to the floor) then if they aren't already rusted, the water rolls right into the channel between the rocker and floor which has no drain holes. Also, I have seen some trucks with a block of foam shoved into the cab corners for sound deadening-- perfect for holding moisture in.