I was stripping the roof on the 68 with a DA, and the center of the roof is oil canning badly. There is some filler work on the roof, but I don't see any evidence of a big dent that would stretch the metal. Is this normal, or should I try to shrink the metal? The area is rather large, and trying to shrink it might make the problem worse. Is there support underneath it that might not be keeping it rigid?

I recently worked on a '73 Mustang that had the same issue. It was unmodified, but we used a few strips of bar stock in a lattice pattern welded under the roof and its very rigid now. Does you '70 do this as well?

http://allshops.org/cgi-bin/community/communityalbums.cgi?action=openalbum&albumid=9980121727059

I have one and love it!!! It is by far the best tool I own and I got alot of stuff:)

The shrinking disc ONLY shrinks what needs to be shrunk there is NO guess work in using the tool.

Using a oxy/fuel torch to shrink metal on that roof and not knowing 100% what you are doing you will end up with a huge mess.

Those shrinking hammers and dollies will butcher your metal rather then shrink it, dont waste the time, effort, money and sheetmetal on those junk tools.

Remove the filler and see whats really causing that oil canning. You might find that working the low areas with a hammer and dolly using the ON dolly method that your oil can disappears.

My link below has some pics of metal finishing(no bondo) a fender. Might atleast give you some ideas...Eric

For the non-body guy---- What is oil canning?

For the non-body guy---- What is oil canning?

Stretched metal. Stressed metal

You REALLY need to read the article at this link... http://www.camaros.net/forums/showthread.php?t=12229

The "Brows" I mention could very possibly be under bondo on your roof. So because you don't see them right off, that doesn't mean they are not there.

Do NOT shrink anything until you have given the roof a good once over following the info in the link.

Brian

LOL I still dont have a clue what oil canned metal looks like...


Is it like when you have a huge but low dent on a roof that seems like it can "plop" itself back into shape but as soon an you look it it wrong.. it plops back into a dent... ? :confused:

It is hard to describe when people don't know what a vintage oil can is like, that is where the term came from. You know the old oil cans like the Tin Man has in the Wizard of Oz? It "clicks" when you push the bottom of the can, it goes in, but then pops back out when you release the pressure from your thumb. When the metal on the cars panel does that, it is oil canning. But we will usually refer to any times the metal goes in loosing shape and stays there only to be popped out with a little pressure. This isn't "real oil canning" but it is usually called that.

Brian

It is hard to describe when people don't know what a vintage oil can is like, that is where the term came from. You know the old oil cans like the Tin Man has in the Wizard of Oz? It "clicks" when you push the bottom of the can, it goes in, but then pops back out when you release the pressure from your thumb. When the metal on the cars panel does that, it is oil canning. But we will usually refer to any times the metal goes in loosing shape and stays there only to be popped out with a little pressure. This isn't "real oil canning" but it is usually called that.

Brian


Ok I had the right idea.. I think.

I recently worked on a '73 Mustang that had the same issue. It was unmodified, but we used a few strips of bar stock in a lattice pattern welded under the roof and its very rigid now. Does you '70 do this as well?

Dave, I haven't checked to 70, but I don't thinkso, because I would have noticed it the last time I washed it. The 68 is very flexible.

Brian, Eric, thanks for the info.

Dave, I checked the roof of the 70 at lunch, and it's as stable as a rock. Wouldn't flex at all.

IMO all roofs are prone to a certain amount of oil canning, are you sure youre not exerting too much pressure while sanding?...its easier to do than you might imagine, make sure you have fresh, sharp sand paper at all times and then allow it do do most of the work ...simply put, "oil canning" is the panel popping in and out of the intended shape or contour.
its almost always best to remove any previous repair material to bare metal and see exactly whats going on, if there is heavy filler, chances are, theres quite a bit more repair on the metal itself you can accomplish...good luck