Rust potential. Why are we so shy to talk about it?

[Barry Wolk]

I had to inform the owner.

As you both know I only have your best interest at heart. I need to tell you about a flaw in the design of the “boxed” frame of every Mark II ever made. I only suspected this from 40 years of experience in the light pole maintenance business. Light pole are falling all over the world from rust eating the steel out from the inside. The very thing is happening on all Mark IIs.

Most steel light poles were never painted on the inside and started rusting the day they’re made. The outsides were cleaned and painted, but, like the Mark II chassis, wasn’t dipped, so rust flakes kept falling to the bottom of the rectangular frame rail that runs the length of the car between the tires. The bumpers attach directly to the frame rails, front and rear.

The frame rails are put together with two pieces of sheetmetal that are [-shaped and ]-shaped and fit inside each other creating a “boxed” frame that’s rectangular, about 2.5” wide and 5” tall, one on each side. A design flaw I’ve found only affects the horizontal sections between both wheels on both sides.

By welding [ and ] together that created an overlap of 1/8” stamped steel. They used stitch-welding, 1" of weld for 3 “ of frame rail length. If you used continuous welds the frame would warp from heat. They never thought these would be around more than 10 years and gave no thought to drainage or longevity. Rain splash, and dew, kept the inside of the steel wet, especially if the car was parked after driving in the rain. The frame has plenty of holes to let it dry out at speed, but has no drain holes to let water out. The frame is held in position at jig holes for welding that let water and mice in, but no drainage to let water or mouse pee out so the rust blooms start pushing apart the frame layers, feeding the building of iron oxide (rust) in the process.



This is looking up through the bottom of the frame where I pointed out to you what might be surface rust, but it’s not. It’s rust that’s eaten through from the topside. I drilled a drainage hole near that exposed rust I burned up 2 drill bits as rust (Iron Oxide) is much harder than steel. You should be able to discern a shiny ring of steel at the top and one at the bottom of the hole. The original steel has been reduced by 75% from 1/8” to maybe 1/32”. The top of the frame rails and the sides are largely unaffected, just where water sat in the bottom of the frame.

Is the car drivable, yes. Is it crashable, no, but it wasn’t very crash-friendly to begin with. Is there anything that can be done about the damage? There is a treatment that seeps into the rust and stabilizes it, but nothing will restore the original integrity. In a way, it could be a godsend in a crash as the tearing metal would absorb some energy before it getting to you. The problem is that it’s not an engineered solution. Anything can go wrong. I would be of no hope in a side-impact, There is nothing inside the door but air and window glass. In a front impact the frame could buckle, forcing the doors closed.

I would start driving the car with great awareness of your surroundings. Better to be stuck at a light than go through an intersection too late. The way it is it will likely outlive us, but had I not made you aware of my findings, I would be remiss, both as your friend and mechanic.

Barry

[Mark Norris]

The frame rails are put together with two pieces of sheetmetal that are [-shaped and ]-shaped and fit inside each other creating a ?boxed? frame that?s rectangular, about 2.5? wide and 5? tall, one on each side. A design flaw I?ve found only affects the horizontal sections between both wheels on both sides.

By welding [ and ] together that created an overlap of 1/8? stamped steel. They used stitch-welding, 1" of weld for 3 ? of frame rail length. If you used continuous welds the frame would warp from heat.

Its quite difficult to find detailed manufacturing drawings for the frame but here is an illustration of the cross section of the outer frame rails and body panels between the wheels taken from an engineering paper the Continental engineers wrote at the time;

Side rails of frame.jpg

Its shows what Barry was describing in the previous post. The channels are fully overlapped top and bottom to make a box section with a high "moment of area" which means, like an I-beam, it has a lot of metal on the top and bottom attached by less metal in the middle. This makes it very stiff in vertical bending. Its also got to be remembered that the side rails can get quite hot from the exhaust pipes so the combination of water, perhaps a little mouse urine, not great ventilation and heat makes a nicely corrosive environment, especially on the low side.

[Barry Wolk]

Here-in lies the problem. With a stitch-welded top seam any water that hit that area would be wicked into the space by capillary action between the layers of steel. Water would have dripped-down from the top and would have drained out the same way, except the rust blocked the way, almost immediately. When water did back up there was no place for it to go. It evaporated, or soaked the rust flakes and they built up in the bottom. After a short period the exits between the stitch welds would seal. There are numerous welding jig holes in the frame about half-way up. Just going through a flooded intersection trapped water at least 2" deep inside the frame. Going through a car wash on a regular basis or just living in Seattle would reduce a frame to buckets of rust.

The center core frame is built the same way, but would seems less susceptible.

[Barry Wolk]

The '56 I'm putting seat belts and front shoulder harnesses on has the best frame I've seen on a Mark II. There is no bulge between welds. All the metal is laying flat between the welds, unlike the '57 I'm just finishing. The owner of that car wasn't happy with what I found, but he appreciates knowing the truth.



Here's an example of rust pressure at work. On Al's '57 this seam is welded shut, trapping water behind it. You can see how even a tiny bit of rust between the frame halves have pushed the unwelded ends apart and reduced the thickness of the metal. Rust is a physical force to be reckoned with.



I found the spare tire well filled with rust flakes. Someone had erroneously replaced the welding jig plug on the bottom with a rubber expanding freeze plug. It's pretty amazing what people do to keep water out, but won't let it out when it needs to be. Just another Mark II rust trap.

However, the one part I've not seen ay rust on is the inside of the 5th gas tank I've drained.

[Roger Zimmermann]

I found the spare tire well filled with rust flakes. Someone had erroneously replaced the welding jig plug on the bottom with a rubber expanding freeze plug. Just another Mark II rust trap.

All vehicles which have the spare wheel in an almost vertical position have the same issue. When I got my '56 Biarritz, the wheel well was gone, eaten by the rust...

[Don Henschel]

One thing I cannot understand is all of the major rust issues with the frame and how many have to deal with it or find another hopefully good frame. I have a 59 Ford sedan that I purchased 40 years ago and rust started and was never dealt with and rust is like cancer that keeps spreading. There is not a salvageable panel anywhere on this car and even the hood has holes in the front. The floor boards are rotted out to the point of feral cats being able to seek shelter within and a while ago during preparing this car for scrapping involving removal of anything of any value, I looked at the frame. The frame looks great as I suspected and the rest of the car is a disaster.
I have dragged home vintage cars laying in deep grass or sitting in a bush for years and the frames always look great.
I find it a total surprise how so many of these Marks have frame rust in comparison. As for mine, I wouldn't know about rust because mine is a southern car and was sold new in Albuquerque New Mexico and there is not one piece of pot metal that has any pits either. The car was searched extensively for rust and none was ever found.