Roof patch causing warp / oil canning

[MP&C]

Likelihood is 100%. Looking at the second picture in your post #38, those rust holes are not from leaves in the drip rail, they are rusting from the inside-out. Over the years humidity has formed inside the truck as it sits in the sun with the windows up. When it cools at night this humidity becomes condensation on the bottom side of the roof skin, where it will pool and collect to the low areas once gravity helps out. What you have showing is normally a small percentage of the rust and pits that are still growing and will be breaking through in the next year or so. If you have priced your paint materials, then I'd say you fully understand how much cheaper this repair will be before paint goes on. If they reproduce a roof skin for your truck I'd say you have a prime candidate now. And it fixes the antenna hole..


For some insight, John has a similar repair he's doing right now on a 66 ford here:


http://www.67-72chevytrucks.com/vboa...=784498&page=7



….starting at post 164. This will give a good idea what lies in store. Where he reformed the lip, you shouldn't need to do so with a reproduction roof skin... And while things are opened up, fix everything that needs it..

[ItWillBeSlow]

Originally Posted by MP&C

Likelihood is 100%. Looking at the second picture in your post #38, those rust holes are not from leaves in the drip rail, they are rusting from the inside-out. Over the years humidity has formed inside the truck as it sits in the sun with the windows up. When it cools at night this humidity becomes condensation on the bottom side of the roof skin, where it will pool and collect to the low areas once gravity helps out. What you have showing is normally a small percentage of the rust and pits that are still growing and will be breaking through in the next year or so. If you have priced your paint materials, then I'd say you fully understand how much cheaper this repair will be before paint goes on. If they reproduce a roof skin for your truck I'd say you have a prime candidate now. And it fixes the antenna hole..


For some insight, John has a similar repair he's doing right now on a 66 ford here:


http://www.67-72chevytrucks.com/vboa...=784498&page=7



….starting at post 164. This will give a good idea what lies in store. Where he reformed the lip, you shouldn't need to do so with a reproduction roof skin... And while things are opened up, fix everything that needs it..

Thanks Robert. One thing I don’t understand is the practical risk associated with the rust that’s inside. If it took 50 years to make the first 3 pinholes, and I remove these “worst” areas and keep water out, then keep the truck dry except the occasional wash, what is the practical risk of rust breaking through again in the future? To me it seems removing the major contributing factors should reduce this risk.

I’m obviously not building a Barrett Jackson truck here, but I am also doubtful that most folks with decent paint jobs replaced a roof skin over a few pin holes, but I am wrong often and that’s how this discussion started!

Any others have past roof skin repairs to share? I may have access to a probe camera and will try and get some interior shots of these areas just for kicks.

[MP&C]

This is a roof repair I have done. The outside had half dozen or so pinholes.. This was the inside..





Given your circumstances, you will likely have similar, and when you weld you will find the thin spots and also find it challenging to weld up due to blowing holes from the thin spots that are hiding. Also, to speak to how dry you plan on keeping it, when you start welding in the vicinity of a deep, scaly pit that is hiding on the back side, the weld activity will awaken such pits that you'll see them again within 2 years, dry or not. It is cheaper to fix now before wasting paint on something that is going to rust through..



Here is a thread on the entire repair. Note the dark grey circles in vicinity of the visible pin holes. This is a tell tale sign of a deep pit getting ready to break through in short order.


https://www.trifivechevys.com/showth...f-rust-repairs







.

[ItWillBeSlow]

Originally Posted by MP&C

This is a roof repair I have done. The outside had half dozen or so pinholes.. This was the inside..





Given your circumstances, you will likely have similar, and when you weld you will find the thin spots and also find it challenging to weld up due to blowing holes from the thin spots that are hiding. Also, to speak to how dry you plan on keeping it, when you start welding in the vicinity of a deep, scaly pit that is hiding on the back side, the weld activity will awaken such pits that you'll see them again within 2 years, dry or not. It is cheaper to fix now before wasting paint on something that is going to rust through..



Here is a thread on the entire repair. Note the dark grey circles in vicinity of the visible pin holes. This is a tell tale sign of a deep pit getting ready to break through in short order.


https://www.trifivechevys.com/showth...f-rust-repairs

.

Thanks Robert, that is an interesting read. I am leaning toward doing the whole roof skin at this point the more this thread evolves.

I think I could handle the task, however I am not sure how to cut the rear seam at the skin. Since I would not save mine, I believe I could cut 1" in front of the seam across the back, drill out the drip rail spot welds and take most of the skin off. Then I would have access to the spot welds on the rear lip to get the last rear 1" of the top skin off.

I am also mildly concerned about aftermarket panel quality. This would not be a "cut and hammer to fit" type panel as with rockers, etc.

If you or anyone else have experience with replacement skins please share. There is not as much information out there on this fix as with other metal tasks on these cabs.

[ItWillBeSlow]

I decided to move forward with the top skin replacement. Picked up the panel yesterday and cut out the old one today. About 2.5 hours to get the spot welds out, and I cut a straight line right in front of the rear seam so far. Still have to get the spot welds off the remaining short strip.

The verdict is: not as bad as I thought, but glad I did it. There is surface rust on everything, a mouse motel, and a lot of nooks and crannies to be wire wheeled and treated. I have 2 small pin holes I hadn't noticed on the interior skin right beside/under my passenger weather stripping, I am unsure If I will fix these or treat and fill.

The top skin definitely has some weaker areas near my previous repairs, you can see this in the photos.

Here are some raw photos before I cleaned out all the crap. The major areas like under the windshield (rats nest area) appear to be very solid, surprisingly. Cant test fit the panel fitment until I get the last strip out of the back seam.

I do need some more input on the metal bond from anyone with experience. I bought a tube of fusor 208b ($50) and the fusor part number gun/dispenser that fits this tube ($75 ). The dispenser is back ordered. This is a 300mL /10.1 oz tube, is there a universal dispenser I could use? Preferably a cheaper one.

Also looking for recommendations for what insulation/sound deadener to put back down.