Re: Roof patch causing warp / oil canning
 

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.

Re: Roof patch causing warp / oil canning
 

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


https://hosting.photobucket.com/albu...s/HPIM5193.jpg


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







.

Re: Roof patch causing warp / oil canning
 

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.

Re: Roof patch causing warp / oil canning
 

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.

Re: Roof patch causing warp / oil canning
 

I plan to also hit the pillars with eastwood internal frame coat/rust encapsulator now that I have access to everything. I will probably POR15 most of the top area. Here are a few pics after vacuum and a few minutes of wire wheel.

Re: Roof patch causing warp / oil canning
 

Test fit panel today. Looks pretty good so far, maybe the best repop I have bought.

There is a 3/16" hump in the middle of the rear seam where it wont lay perfectly plat. Needs about 10# pressure to hold it down flush with the seam. May get better once I clean up all the joints properly, I plan to strap it down during the cure to hold it solid.

I was planning on bonding the rear seam, and welding the front and rear sides. Please share if anyone has input for otherwise.

Re: Roof patch causing warp / oil canning
 

First off, congrats on filling the antenna hole, can't even see where it was anymore.. :metal:

Next, consider who you're getting advise from here, take it with a grain of salt, your truck, your decisions, etc..

I haven't used the panel adhesive to speak from a position of authoritay. But what I have read is that the panels that are being glued? together should be clamped tightly across the entire seam where the adhesive is being used. In my interpretation, clamped tightly means there will be minimal adhesive between the two panels for maximum strength, vs looking like someone got happy with a caulking gun to fill a void. It also means that with the (steel) headliner still in there and in the way, you're not clamping jack together. So no "proper" use of the adhesive is possible. You already know what's coming next, this is Robert, after all.

My thoughts are to remove the headliner and rear window surround in their entirety, KEEPING THEM ATTACHED TOGETHER, by removing spot welds around rear window opening, around door opening, around windshield opening, and across bottom beneath window.

Attachment 2095944


SIDE NOTE: Part of the support of the rear cab panel that attaches to the roof in the back is the crown of the roof skin. So where you see the roof skin needing to come down, I see the rear section needing to come up to meet the roof skin, or a meet in the middle. You take the old roof out, and it removes some of the support where the top center of the rear panel may tend to drop on it's own accord. But of course, I'm looking at color 8x10 glossy's on my screen here, so the final determining factor is what you see in front of you and how the panels react as you bring them together.


Next, before welding the outer skin in place, repair any of the gutter, bracing, A or B pillars, etc now that you have ready access. Now you can properly position the outer skin, clamp to the rear section as needed, and perform spot or plug welds to attach as needed. Then repair any damage to the headliner assy before aligning it back inside and welding back in place.


For the dual cartridge gun that you'll now need for seam sealer in the drip rail, keep looking. I paid 39 for mine. And I would suggest epoxy primer inside all the nooks and crannies while accessible. A much better choice over POR, which will give off noxious fumes if it comes close to the heat from welding.

Re: Roof patch causing warp / oil canning
 

Thanks for the feedback Robert. I will say that further disassembly of the cab and interior is not particularly appealing to me right now :lol:

I do however think/wonder that an additional clamping method could be worked up using j-hooks or a similar small clip. Attaching a hook to the back panel lip, that the new panel lip could "slide under" after applying the metal bond, would help provide some actual clamping force, and a mechanical attachment that would prevent lift or at least reduce risk that the bond could break over time. I recognize this is not by the book or per the instructions of the panel bond, however it may be practical.

I may also start a dedicated thread on this topic in the main section due to the low traffic in this forum, and how this topic has shifted from the original thread intent. The fact that this panel is reproduced means there are at least a moderate amount of people performing this repair - surely there are a few more lurkers here who have done it.

Re: Roof patch causing warp / oil canning
 

I hope I never have to do one of these repairs but I am thoroughly enjoying the read.

Best of luck to you getting it done perfectly. Looking good so far. My only input is to not use por15. I have had bad luck with it and seen far too many similar stories.

Re: Roof patch causing warp / oil canning
 

I have used panel bond several times in positions where if I could have gotten in there to clamp it I could’ve welded it, I used panel bond when I put the big back window in my 65 by making sure that the two panels lined up properly and touching each other All the way across I installed the inner cab Using the panel bond and clamped the cab around the door opening and window The panel bond that squeezed out of the joint was wiped off leaving a perfect seem and then spot welded the rest.
Just for kicks I have taken some of the leftover panel bond and pressed couple pieces of scrap together it’s stronger than a weld you can’t rip it apart

Re: Roof patch causing warp / oil canning
 

Well it wouldn’t let me add a picture to my previous post but this is the inner cabAttachment 2096226

Re: Roof patch causing warp / oil canning
 

After 5/6 hours of wire wheeling, I have cleaned everything up as much as reasonably possible. About 85% of the surface area is clean and perfect for primer. The front "gutter" is lightly pitted and will not wire wheel to shiny metal. There are also some tight places in the corners that cannot be cleaned. I think this application is more favorable for POR15 over primer - thoughts? Should i put down some POR15 and primer over this?

The only heavier pitted areas are the corner braces which I am not concerned about, they will not affect a visible panel.

Re: Roof patch causing warp / oil canning
 

Thanks for the info!

Re: Roof patch causing warp / oil canning
 

The areas that didn't clean up with a wire brush need to be sandblasted to get rust out of the pits. An inexpensive spot blaster would be a good option for small areas if you don't already have a blaster. Then use epoxy to coat everything. Por15 or similar "paint over rust" products don't convert/kill the deep rust, and that looks like there will be some deeply rusted pits that'll show up when blasted.

Re: Roof patch causing warp / oil canning
 

Thanks. I do have a spot blaster, I had previously blasted the full drip rail before I took the top skin off. I was hoping to get away with not using it due to how slow and nasty it is for large areas. I did find 2 pin holes hiding in the pitted areas, really close to the weather stripping inside. Ill probably start the blasting and see how it goes and cross my fingers more don't show up.

Re: Roof patch causing warp / oil canning
 

Is peeling off the roof skin to deal with whatever is inside a wise thing to do on any truck just in case?

I have no rust visible through the paint on either side, but it has not been blasted yet. I don't really want to skin it, but if it's super wise......

Re: Roof patch causing warp / oil canning
 

Im not the most experienced to answer this question, but Ill throw out my $.02.

If you aren't in a huge rush and can spare an extra $250ish for the price of the panel, I don't think its a bad idea. If you end up with little or no visible rust in any of the roof area after you're done blasting, it may be a safe assumption that your cab is in decent shape in this regard and this would be a waste of effort for you.

I may have gotten lucky, but I am very happy with the quality of the new skin I received. Once this is complete I expect to have about 30 hours in the removal, clean up, and install of the new skin. Not done yet so time will tell..

So far I am happy with my decision to take mine off. I do have 2 or 3 pinholes to address and am on the fence about cut and weld or hit with a little filler after priming and sandblasting and be done with them.

Re: Roof patch causing warp / oil canning
 

Got the "gutter" and perimeter of the roof area 97% clean with my spot blaster. There is a small amount of rust left in some of the larger pits that I will be leaving as-is.

I did discover some more pinholes on the passenger side - my spot blaster created these while cleaning. I've almost got this patched up. A few more hours to go and it will be ready for some primer. This area is hard to patch due to blowing holes in the thinner metal around the patch.

This is about 6-7 hours of spot blasting from the photos above.

Re: Roof patch causing warp / oil canning
 

Well..the spot blaster didnt "create" the holes...it just uncovered them....
It's looking good ..!!!

Re: Roof patch causing warp / oil canning
 

I agree with this assessment :lol::lol:

Re: Roof patch causing warp / oil canning
 

Are those holes more accessible from the inside of the cab (underside) any better than the topside? If you find yourself blowing holes try more wire feed speed and less time on trigger pull..

Another option would be to get a small piece of copper pipe and trim/bend to fit snugly to the area of the pin holes. Then weld to fill the holes using copper as a backer.

Another option would be to cut out the area and weld in a new piece. While you are at this stage it would be a shame to not get all of it fixed with metal/weld while it's accessible (before the roof skin goes on).

Re: Roof patch causing warp / oil canning
 

Thanks Robert. I was able to do this from the bottom/inside. I hadn't thought of the pipe idea, that probably would have saved some headache. I was able to get it done finally.

The two pinholes to the right I was able to weld from the top side, with some copper as a backer on the interior. They filled very nicely.

I put this aside for a week due to work and am getting back to it this week. I hope to primer the new skin and top of the cab this week and get to the skin install by the next week or so.

Re: Roof patch causing warp / oil canning
 

Today I shot some SPI epoxy primer on the inside of my new skin, and the top of my cab.

I had some fisheye/solvent pop/??? in the thicker spots on my first coat. Was this due to me laying it on too thick? See pictures. Overall it looks very nice. This was my first time shooting actual paint materials through an HVLP gun (Devilbiss FLG4). This was a good practice run for future primer-ing.

I hope to get the new skin installed within the next week.

Re: Roof patch causing warp / oil canning
 

That's normal, SPI doesn't like to go on very wet on the first coat. I still forget and do that from time to time :lol:

Re: Roof patch causing warp / oil canning
 

Got my new skin installed last week. About 50 spot welds on the front and sides, and 3M panel bond on the rear seam. Install and fitment went well.

I tested the panel bond on a couple pieces of scrap, about 1 square inch bonded together. I could not separate the pieces without risking an injury. I was able to get it started, and about half way through the separation stopped. After the small test patch I feel pretty confident in the quality of the bond on the rear seam.

Thanks to Lorne for some additional tips and tricks for using the panel bond. I have about 40-50 hours of work from start to finish in this whole project. Technically speaking, this was no harder than some rocker panels. I appreciate all the comments and feedback in this thread.

Re: Roof patch causing warp / oil canning
 

Looks good!!

Re: Roof patch causing warp / oil canning
 

That panel bond is tuff stuff I was totally amazed when I did my test trying to separate the two pieces and could only rip the metal. looks good it also sealed your seem I think if I ever did a roof I would consider panel bond all the way around especially on the earlier models like my 65 that way you wouldn’t be relying strictly on seam sealer