Rust repair under vinyl top...

[cozwurth]

OK, this question is mainly for my '70 Chevelle, but since several H-body cars came with at least a partial vinyl top I'll ask away...

I peeled the top off of my Chevelle after seeing many bumps under the vinyl. I started scraping the glue and fuzz off, and then sanding the surface rust off. Several of the "bumps" became small "holes" once I got the rust out. I'm not planning on putting another vinyl top on this car, so I want to fix these holes to prep for paint. I'm not sure I can weld them up without warping the roof or burning through and making them much larger. Is there another way to permanently fix these holes in the roof?

[res0o7eb]

I've heard some people have used Duraglas for minor, small, non-structural rust-through. I haven't tried it myself, but I do have a similar problem on my 67 Caprice Sport Coupe 396.

[ColinOpseth]

Dave,
Easy fix...cut the roof off and wrap the jagged edges with duct tape. The -ahem- Mexicans here in Cali still do it quite regularly and they appear to be pretty handy with a roll.

Just kidding,t hough. You can probably fiberglass it or have the area cut out and then a new section welded in. I'd be just as worried about the inner lining of the whole roof as much as the outer cosmetic portion.

Later,
Colin

[cjbiagi]

Unfortunately the only real way to repair rust is to remove it and replace with new metal. Anything less is temporary at best and with the price of paint jobs, do you really want to have to do it over? The other option is to repair and revinyl it.

[cozwurth]

Unfortunately the only real way to repair rust is to remove it and replace with new metal. Anything less is temporary at best and with the price of paint jobs, do you really want to have to do it over? The other option is to repair and revinyl it.

Clyde,
I know you're right, and I've even said it before myself. Fix it right, or fix it twice. If it was on any other part of the car I would not hesitate to cut it out and weld in new metal. I have to replace the entire rear section of the driver side sail panel and a large portion of the pass side sail panel as well. Those areas have body lines to follow and to help keep it from warping, the middle of the roof does not. I had actually thought about getting one of POR15's Floorboard Repair Kits to use on the roof. They use their POR15 paint and a fine fiberglass cloth to repair minor rust and pin holes in floorboards. I thought about using it on the inside of the roof and then using a skim coat of filler to finish off the outside. I've used POR15 in the past, and I know it's tough as nails, but I'm not convinced that it will last when used that way.

How about this idea...

Grind the rust out to solid steel. Then, cut a small patch of steel, just larger than the rust hole, and have someone hold the patch to the bottom side while I tack it in place from the top. A few tack welds will actually fill the holes completely since they're no larger than pencil leads right now. They should be no larger than pencil erasers once I finish grinding. The underside could be finished off with a coat of POR15 to seal it from the air. A little grinding on the welds and a skim coat of filler should have it looking good.

What do you think?

Then again, I have always wanted a convertible... What brand of duct tape are they using, Colin?

[peterpan]

i had a 70 chevelle with the same problem i cut the rust out and welded in patch panels then had a shop put a new vinal top back on shortly after finishing it i moved from northern idaho back to rock springs wyo so i had to sell it but it wasn't that bad to fix
use a mig welder on a low setting take your time and weld no more than a half inch at a time and move around your patch if its small take breaks to let it cool down the better you fit the patch the better it will look

[AusRs]

there is another way to repair rust ..its the old method of lead wipeing
however that is not usually done by the home handyman

mig on low setting as advised stitch weld around the patch ie weld a small area of the patch then move diagonally opposite and work around the patch ......also keep a cold wet cloth on the roof as close as you can to where you are welding to stop the heat transfer through the rest of the roof ...........hope that all makes sense as i described it ..it will shrink a little BUT not that much

[cozwurth]

Aus,
That makes sense to me. Anything to keep the heat to a minimum and contained in a small area would be a good thing.

I used a small propane torch and a wet rag to fix an 'oil-can' type dent in the front fender of my '81 Malibu wagon recently, so I know what heat can do. Amazing how much that dent swelled up while the heat was applied...

Thanks,

[AusRs]

just as a matter of interest i know a guy in the north east of usa that removed a sunroof from a 3rd gen camaro ......cant even tell it was there now ...just have to work neat and carefull !

[ozzymoose]

Ok cozwurth, this is a bit long-winded but i would do this---- If the interior hood lining is in, take it out have a good look inside. Go round and circle all the pin holes with a felt tip pen inside and out for later ref. More than 1/2 the time the body glue between roof supp and the turret breaks they rub through the rust protection causing what you see,(that and vinyl lol).Any rust near the supports means that support needs to come out. Hit all the rusted bits with kill rust or the usa eqiv 2 times.Clean all areas well wire brush ect. If you have for eg a 1/4 inch hole drill/cut it out to double its size to ensure sweet metal. Whatever method you use make sure the drill/die/cutter is on a slower speed and be gentle. Find the same gauge flat steel and fashion a 1/2 inch button from it. Drill 1/8 in the centre poke some fence wire through it a bit then tack weld it to the back,now you have a patch with a handle lol. If you have a mig with a stitch/tack feature now is the time to set it to its shortest time setting.Now this will sound odd to ppl, but use the fattest wire that will fit in your mig why--- eg- 1.5 mm wire @ 90v has double the heat as 3mm wire because the same voltage/amps/heat is spread over twice the area with thw 3mm, less heat less distortion.Grab your patch and holding the wire lower the button in flush with the body, tack it in. If your mig has no stitch feature just aim and tap the trigger just as good. Take small bites at it, you will get enough peno, it will stick its sheet metal. I used to do 4 or 5 tacks then grind it with a slow speed die with and emery wheel to keep heat and distortion to a min. Once you are happy with it cut the wire from the back and tack the drill hole. grind smooth and and make your way to the next one, this way isnt easy but you will do it just once.

[cozwurth]

Thanks, Moose.

Sounds like a pretty good method. Most of the holes are out in the open area of the roof, so holding the patch from the bottom will be easy. There are a couple that are over the middle support for the dome light and a couple over the front near the windshield. Your method will definitely help there.

Thanks again,