The roof on my 1970 has been exposed to the elements for several years,prior to when I purchased the car. It had a vinyl top at one time. The roof has a few holes clear through the sheetmetal, severe corrosion has thinned it in other spots. I have begun to sand it smooth, in preparation to use POR on it. I plan to reinstall a vinyl top following completion of a restoration. Question: Am I on the right track? After getting the scale and rust off, shall I use the POR primer before filling in the holes? Or, would welded patches be the preferred route to go with the roof in the shape it is in? If anyone can guide me from start to finish on the resto here, I'd appreciate it. I do have an entire roof from a 1972 which I can cut patches from, or should I allow a bodyshop to swap the roof sections? Thanks!
(I do have pics, but am not adept at posting them here!)

Por 15 is a great product, but it's not a cure for all ailments. In my opinion and from my own experience, it's not well suited for exterior applications. It's best suited for the backside of sheetmetal in rust prone areas like lower quarters and in areas that are not readily visible like window channels and floor pans. They do make a tie coat primer which allows you to use standard automotive finishes over the top of it, so I guess you could use Por as a substrate on an exterior surface. I haven't tried it, so I can't say if it will work or not and would not want to make a recommendation without trying it for myself first. It may work very well. But the best way to fix any rust is to cut it out and weld in new metal. My recommendation here is to reskin the roof if you can locate a suitable donor. I don't think roof skins are being reproduced.

I too have exactly the same problem you have vetteman72. Vinyl before, rust, holes. I have been wondering what to do with it. I don't have another roof to attach and would not like to try that anyway.

Do you have the problems of rust pits all over your roof in the middle back section with rusted through holes?

This is the part that bothers me and I was going to patch in the rust holes with new metal and por15 the rest, prime, paint and apply new vinyl. Heard that sand blasting this area will warp it bad.

Hope someone else can chime in here and help us both. Sorry this wasn't an answer and hope you don't mind me adding to it.

Marty

Well, following my long post, I went back and did some research on the subject of rust, and roof repairs seemed to come up quite a bit in the past! I do have several spots where holes are through, or almost through the sheetmetal. I have done bodyfiller and paint in the past, but no welding, or panel replacement, and i plan to start, but NOT on the roof! I am looking for professional advice on whether filler can be expected to hold, what type is best, and whether I should prime bare metal and THEN apply the filler, or the other way around. As i said, I do plan to reinstall a vinyl top, but it seems that the roof has quite a bit of flexing due to it's size and lack of center reinforcement, so is filler even an option? Any and all advice or discussion is appreciated!

same thing here i welded patches in all the holes the small spots i just filled in with mig weld of course some warpage so i worked the metal and started filling . i figured this was better than just bondo over the holes i plan on keeping it hardtop just do really nice body work and use the best materials and it will be fine.

"The tires ain"t workin' if they're not SMOKINNNN!!!
Well, feeling pretty discouraged with this roof. I found a hole almost the size of a marble, which had been filled in with plastic filler, and with 2-3 devices at my disposal (36 grit paper on a 6"DA; a 3" stripping pad in a electric drill, and determination)
How much harder could cutting it off and splicing the donor roof on?

I had this problem with my 69. I sanded the roof down to bare metal and coated it with Corroless from Eastwood. After that, sealer was layed down then the primer and base coat. Then I put a vinyl top back on it. There were no signs of rust on the roof after 6 months so I believe it will be fine.

So BlueSS454......
Did you have to build-up a significant layer to fill in the rusted ares? Did the sealer take care of it, or by the time the base coat was on it had leveled out enough for the vinyl?
I recognize the waterfront shot of the '70- You weren't in NorthEast, MD, this year were you? We should chat about South Jersey. (from a former resident)

Well, I applied chemical stripper, sanded and wirebrushed the roof. Then I hosed it off, and when dry I applied the first coat of Eastwood's Rust Encapsulating primer. It sure looks better than before! I will have to give a second coat, and proceed with cutting out the holes, and then filling the low spots.Maybe I should have cut the bad sections out first?????

MARTINSR has an excellent technique for replacing a roof. I'll see if I can find the post.

I think this is the one.

http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=3;t=008497#000001

Thanks for the help, Randy. It looks like a big job to me- probably too big. But I'll keep it handy, and see what kind of additional opinions surface. I did opt for Eastwood's product as opposed to POR. I guess I agree that there are applications for it. I will use it down in the cavities behind the skins, etc.

If you have a complete roof skin then replace the skin. Why cut out patches when you can replace the whole thing and make a better repair in the end???

POR and the like are nothing but coverups! They dont prevent rust they hide it. The proper way to stop it is to use the PROPER paint products made by a PAINT company.

Skinning a roof is VERY easy, alot easier then trying to patch one up thats for sure

i'm kind of a shade tree mechanic....so don't quote me on this, but i used por-15 over my whole body before i put the paint on. i have a friend who owns a body shop (he owns the cleanest 69 camaro i have ever seen) and he said he did this to his camaro and recommended i do it to my chevelle as well (he's never steered me wrong before when i comes to bodywork). just my opinion.
-Jay

Paint is made by CHEMICAL companies, not PAINT companies. DuPont built his first factory in 1802 to make GUNPOWDER. His first non-explosive product was artificial leather. They started making dyes in the late 1800's and paints for automobiles in the early 1920's. DuPont was a chemist who thought he could do it better, just like the young-gun chemists of today. Bill Gates code for Windows was poo-poo'd by IBM. These guys making POR-15, RustBullet or any other similar product are just trying to prove the same thing. That they can improve on what is currently available. POR-15 and the rest are PRIMERS with adatives. Flouride is ADDED to water but not a substitute for brushing. Chemicals added to primer (can you say etch?) are not a substitute for panel replacement, just an improvement on plain ol' primer.

from a autobody shop point of view i would replace the whole roof no mater what it cost,as you will save in the long run,a donor car should be easy to find or just buy a roof,and keep the vinyl under your ass and off the roof

I replaced the whole roof skin on my car, and it was not that difficult. I also ahd a vinyl top from the factory, but did not want to kep it on after doing my resto. I figured that replacing the whole skin was a whiole lot easier, and risk than trying to patch many different holes on the top without causing major warpage. The replacement roof skin cost me 35 bucks and about 15 minutes with a torch.

Geez! You guys are talking me into this! graemlins/hurray.gif
I have a spare roof in much better shape on the top surface, but it seems a bit worse around the front windshield area. The other issue as I see it,is that when I took it off the donor car, I did not really cut thru the sail panel seam where it meets the top of the quarter. I cut above all that. Does that present a problem, or does it just mean another seam, 1-2 inches above the factory seam? Also, what about the drip rails? I looked over the roof, and I guess there are a bunch of spot welds across the top of the windshield, holding the skin to the roof inner structure?

As you can see, you get mixed opinions on Por 15. I've had nothing but success with Por products and it absolutely is NOT snake oil. I've used it on clean, brand new sheetmetal and it works as advertised at PREVENTING rust. My battery tray is the best example of this. Five years later, it still looks as good as it did the day I painted it. It does seal better than conventional automotive paints in my opinion. But like I said, it does have its uses as well as its limitations, as does any product. I'm not sold on using it for exterior surfaces and since most rust usually starts on the back sides of most panels, it really doesn't make sense to apply it to the exterior.

Some people cannot get Por 15 to work for them no matter how closely they follow the instructions. I cannot explain why this is so. It's not accurate for those individuals to say Por does not work. It just didn't work for them for whatever reason.

Good luck with the reskin. Whatever you do, take your time and measure everything twice before cutting or welding.

I am wondering if those guys that cannot get por15 to work have something in their water when they rinse after using metal ready. That would be the only thing it could be IMHO. The marine clean is awesome stuff too. Maybe some well water enriched with minerals has some effect. I don't know, just a guess. Something to consider.