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-   -   Roof patch causing warp / oil canning (https://67-72chevytrucks.com/vboard/showthread.php?t=820201)

nsb29 04-17-2021 08:01 PM

Re: Roof patch causing warp / oil canning
 
1 Attachment(s)
Well it wouldn’t let me add a picture to my previous post but this is the inner cabAttachment 2096226

ItWillBeSlow 04-17-2021 10:30 PM

Re: Roof patch causing warp / oil canning
 
3 Attachment(s)
Quote:

Originally Posted by MP&C (Post 8909055)
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.

Quote:

Originally Posted by tinydb84 (Post 8909253)
My only input is to not use por15. I have had bad luck with it and seen far too many similar stories.

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.

ItWillBeSlow 04-17-2021 10:35 PM

Re: Roof patch causing warp / oil canning
 
Quote:

Originally Posted by nsb29 (Post 8909813)
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

Thanks for the info!

theastronaut 04-19-2021 06:28 PM

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.

ItWillBeSlow 04-19-2021 09:51 PM

Re: Roof patch causing warp / oil canning
 
Quote:

Originally Posted by theastronaut (Post 8910640)
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.

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.

SkinnyG 04-21-2021 12:30 AM

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......

ItWillBeSlow 04-21-2021 09:14 PM

Re: Roof patch causing warp / oil canning
 
Quote:

Originally Posted by SkinnyG (Post 8911186)
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......

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.

ItWillBeSlow 04-25-2021 11:35 AM

Re: Roof patch causing warp / oil canning
 
3 Attachment(s)
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.

mongocanfly 04-25-2021 04:21 PM

Re: Roof patch causing warp / oil canning
 
Well..the spot blaster didnt "create" the holes...it just uncovered them....
It's looking good ..!!!

ItWillBeSlow 04-25-2021 08:45 PM

Re: Roof patch causing warp / oil canning
 
Quote:

Originally Posted by mongocanfly (Post 8913310)
Well..the spot blaster didnt "create" the holes...it just uncovered them....
It's looking good ..!!!

I agree with this assessment :lol::lol:

MP&C 04-27-2021 12:10 AM

Re: Roof patch causing warp / oil canning
 
Quote:

Originally Posted by ItWillBeSlow (Post 8913185)
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.

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).

ItWillBeSlow 05-03-2021 11:34 AM

Re: Roof patch causing warp / oil canning
 
1 Attachment(s)
Quote:

Originally Posted by MP&C (Post 8913885)
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).

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.

ItWillBeSlow 05-06-2021 08:27 PM

Re: Roof patch causing warp / oil canning
 
4 Attachment(s)
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.

theastronaut 05-06-2021 08:36 PM

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:

ItWillBeSlow 05-16-2021 09:00 PM

Re: Roof patch causing warp / oil canning
 
5 Attachment(s)
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.

MP&C 05-18-2021 03:43 AM

Re: Roof patch causing warp / oil canning
 
Looks good!!

nsb29 05-18-2021 08:39 AM

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


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